switch majority of installers to async implementation (#574)

66 files changed, 510 insertions, 286 deletions

diff --git a/Makefile b/Makefile
index 48a28d7a..4a7fc81c 100644
--- a/Makefile
+++ b/Makefile
@@ -8,15 +8,15 @@ dependencies:
 clean_dependencies:
 	rm -rf dependencies
 
-.PHONY: clean_servers
-clean_servers:
+.PHONY: clean_fixtures
+clean_fixtures:
 	rm -rf "${INSTALL_ROOT_DIR}"
 
 .PHONY: clean
-clean: clean_servers clean_dependencies
+clean: clean_fixtures clean_dependencies
 
 .PHONY: test
-test: clean_servers dependencies
+test: clean_fixtures dependencies
 	INSTALL_ROOT_DIR=${INSTALL_ROOT_DIR} $(NVIM_HEADLESS) -c "call RunTests()"
 
 # vim:noexpandtab
diff --git a/lua/nvim-lsp-installer/core/fs.lua b/lua/nvim-lsp-installer/core/fs.lua
index f3db813a..3819bd51 100644
--- a/lua/nvim-lsp-installer/core/fs.lua
+++ b/lua/nvim-lsp-installer/core/fs.lua
@@ -59,10 +59,33 @@ end
 
 ---@async
 ---@param path string
+function M.mkdirp(path)
+    log.debug("fs: mkdirp", path)
+    if vim.in_fast_event() then
+        a.scheduler()
+    end
+    if vim.fn.mkdir(path, "p") ~= 1 then
+        log.debug "fs: mkdirp failed"
+        error(("mkdirp: Could not create directory %q."):format(path))
+    end
+end
+
+---@async
+---@param path string
 ---@param new_path string
 function M.rename(path, new_path)
     log.debug("fs: rename", path, new_path)
     uv.fs_rename(path, new_path)
 end
 
+---@async
+---@param path string
+---@param contents string
+function M.write_file(path, contents)
+    log.fmt_debug("fs: write_file %s", path)
+    local fd = assert(uv.fs_open(path, "w", 438))
+    uv.fs_write(fd, contents, -1)
+    assert(uv.fs_close(fd))
+end
+
 return M
diff --git a/lua/nvim-lsp-installer/core/context.lua b/lua/nvim-lsp-installer/core/installer/context.lua
index 128ad417..ad956178 100644
--- a/lua/nvim-lsp-installer/core/context.lua
+++ b/lua/nvim-lsp-installer/core/installer/context.lua
@@ -1,11 +1,9 @@
 local spawn = require "nvim-lsp-installer.core.spawn"
 local log = require "nvim-lsp-installer.log"
-local Optional = require "nvim-lsp-installer.core.optional"
 local fs = require "nvim-lsp-installer.core.fs"
-local settings = require "nvim-lsp-installer.settings"
-local Result = require "nvim-lsp-installer.core.result"
 local path = require "nvim-lsp-installer.path"
 local platform = require "nvim-lsp-installer.platform"
+local receipt = require "nvim-lsp-installer.core.receipt"
 
 ---@class ContextualSpawn
 ---@field cwd CwdManager
@@ -57,111 +55,80 @@ function ContextualFs:dir_exists(rel_path)
 end
 
 ---@class CwdManager
+---@field private boundary_path string @Defines the upper boundary for which paths are allowed as cwd.
+---@field private cwd string
 local CwdManager = {}
 CwdManager.__index = CwdManager
-function CwdManager.new(cwd)
-    return setmetatable({ cwd = cwd }, CwdManager)
+
+function CwdManager.new(boundary_path, cwd)
+    assert(type(boundary_path) == "string")
+    return setmetatable({
+        boundary_path = boundary_path,
+        cwd = cwd,
+    }, CwdManager)
 end
+
 function CwdManager:get()
-    return self.cwd
+    return assert(self.cwd, "Tried to access cwd before it was set.")
 end
+
+---@param new_cwd string
 function CwdManager:set(new_cwd)
+    assert(type(new_cwd) == "string")
+    assert(
+        path.is_subdirectory(self.boundary_path, new_cwd),
+        ("%q is not a subdirectory of %q"):format(new_cwd, self.boundary_path)
+    )
     self.cwd = new_cwd
 end
 
 ---@class InstallContext
+---@field public name string
 ---@field public receipt InstallReceiptBuilder
 ---@field public requested_version Optional
 ---@field public fs ContextualFs
 ---@field public spawn JobSpawn
----@field private cwd_manager CwdManager
----@field private destination_dir string
+---@field public cwd CwdManager
+---@field public destination_dir string
+---@field public stdio_sink StdioSink
 local InstallContext = {}
 InstallContext.__index = InstallContext
 
 function InstallContext.new(opts)
-    local cwd_manager = CwdManager.new(opts.cwd)
+    local cwd_manager = CwdManager.new(opts.boundary_path)
     return setmetatable({
-        cwd_manager = cwd_manager,
+        name = opts.name,
+        cwd = cwd_manager,
         spawn = ContextualSpawn.new(cwd_manager, opts.stdio_sink),
         fs = ContextualFs.new(cwd_manager),
-        receipt = opts.receipt,
-        requested_version = opts.requested_version,
+        receipt = receipt.InstallReceiptBuilder.new(),
         destination_dir = opts.destination_dir,
+        requested_version = opts.requested_version,
+        stdio_sink = opts.stdio_sink,
     }, InstallContext)
 end
 
----@deprecated
----@param ctx ServerInstallContext
----@param destination_dir string
-function InstallContext.from_server_context(ctx, destination_dir)
-    return InstallContext.new {
-        cwd = ctx.install_dir,
-        receipt = ctx.receipt,
-        stdio_sink = ctx.stdio_sink,
-        requested_version = Optional.of_nilable(ctx.requested_server_version),
-        destination_dir = destination_dir,
-    }
-end
-
-function InstallContext:cwd()
-    return self.cwd_manager:get()
-end
-
----@param new_cwd string @The new cwd (absolute path).
-function InstallContext:set_cwd(new_cwd)
-    self
-        :ensure_path_ownership(new_cwd)
-        :map(function(p)
-            self.cwd_manager:set(p)
-            return p
-        end)
-        :get_or_throw()
-end
-
----@param abs_path string
-function InstallContext:ensure_path_ownership(abs_path)
-    if path.is_subdirectory(self:cwd_manager(), abs_path) or self.destination_dir == abs_path then
-        return Result.success(abs_path)
-    else
-        return Result.failure(
-            ("Path %q is outside of current path ownership (%q)."):format(abs_path, settings.current.install_root_dir)
-        )
-    end
-end
-
 ---@async
 function InstallContext:promote_cwd()
-    local cwd = self:cwd()
+    local cwd = self.cwd:get()
     if self.destination_dir == cwd then
         log.fmt_debug("cwd %s is already promoted (at %s)", cwd, self.destination_dir)
-        return Result.success "Current working dir is already in destination."
+        return
     end
     log.fmt_debug("Promoting cwd %s to %s", cwd, self.destination_dir)
-    return Result.run_catching(function()
-        -- 1. Remove destination dir, if it exists
-        if fs.dir_exists(self.destination_dir) then
-            fs.rmrf(self.destination_dir)
-        end
-        return self.destination_dir
-    end)
-        :map_catching(function(destination_dir)
-            -- 2. Prepare for renaming cwd to destination
-            if platform.is_unix then
-                -- Some Unix systems will raise an error when renaming a directory to a destination that does not already exist.
-                fs.mkdir(destination_dir)
-            end
-            return destination_dir
-        end)
-        :map_catching(function(destination_dir)
-            -- 3. Move the cwd to the final installation directory
-            fs.rename(cwd, destination_dir)
-            return destination_dir
-        end)
-        :map_catching(function(destination_dir)
-            -- 4. Update cwd
-            self:set_cwd(destination_dir)
-        end)
+    -- 1. Remove destination dir, if it exists
+    if fs.dir_exists(self.destination_dir) then
+        fs.rmrf(self.destination_dir)
+    end
+    -- 2. Prepare for renaming cwd to destination
+    if platform.is_unix then
+        -- Some Unix systems will raise an error when renaming a directory to a destination that does not already exist.
+        fs.mkdir(self.destination_dir)
+    end
+    -- 3. Move the cwd to the final installation directory
+    fs.rename(cwd, self.destination_dir)
+    -- 4. Update cwd
+    self.cwd:set(self.destination_dir)
 end
 
 return InstallContext
diff --git a/lua/nvim-lsp-installer/core/installer/init.lua b/lua/nvim-lsp-installer/core/installer/init.lua
new file mode 100644
index 00000000..03b2de01
--- /dev/null
+++ b/lua/nvim-lsp-installer/core/installer/init.lua
@@ -0,0 +1,65 @@
+local log = require "nvim-lsp-installer.log"
+local path = require "nvim-lsp-installer.path"
+local fs = require "nvim-lsp-installer.core.fs"
+local Result = require "nvim-lsp-installer.core.result"
+
+local M = {}
+
+---@async
+---@param context InstallContext
+local function write_receipt(context)
+    if context.receipt.is_marked_invalid then
+        return log.fmt_debug("Skipping writing receipt for %s because it is marked as invalid.", context.name)
+    end
+    context.receipt:with_name(context.name):with_schema_version("1.0a"):with_completion_time(vim.loop.gettimeofday())
+    local receipt_success, install_receipt = pcall(context.receipt.build, context.receipt)
+    if receipt_success then
+        local receipt_path = path.concat { context.cwd:get(), "nvim-lsp-installer-receipt.json" }
+        pcall(fs.write_file, receipt_path, vim.json.encode(install_receipt))
+    else
+        log.fmt_error("Failed to build receipt for installation=%s, error=%s", context.name, install_receipt)
+    end
+end
+
+---@async
+---@param context InstallContext
+---@param installer async fun(ctx: InstallContext)
+function M.execute(context, installer)
+    log.fmt_debug("Executing installer for name=%s", context.name)
+    local tmp_installation_dir = ("%s.tmp"):format(context.destination_dir)
+    return Result.run_catching(function()
+        -- 1. prepare installation dir
+        context.receipt:with_start_time(vim.loop.gettimeofday())
+        if fs.dir_exists(tmp_installation_dir) then
+            fs.rmrf(tmp_installation_dir)
+        end
+        fs.mkdirp(tmp_installation_dir)
+        context.cwd:set(tmp_installation_dir)
+
+        -- 2. run installer
+        installer(context)
+
+        -- 3. finalize
+        write_receipt(context)
+        context:promote_cwd()
+    end):on_failure(function(failure)
+        context.stdio_sink.stderr(tostring(failure))
+        context.stdio_sink.stderr "\n"
+        log.fmt_error("Installation failed, name=%s, error=%s", context.name, failure)
+        pcall(fs.rmrf, tmp_installation_dir)
+        pcall(fs.rmrf, context.cwd:get())
+    end)
+end
+
+---@param installers async fun(ctx: InstallContext)[]
+function M.serial(installers)
+    ---@async
+    ---@param ctx InstallContext
+    return function(ctx)
+        for _, installer_step in pairs(installers) do
+            installer_step(ctx)
+        end
+    end
+end
+
+return M
diff --git a/lua/nvim-lsp-installer/core/managers/go/init.lua b/lua/nvim-lsp-installer/core/managers/go/init.lua
index 96706368..d73a250c 100644
--- a/lua/nvim-lsp-installer/core/managers/go/init.lua
+++ b/lua/nvim-lsp-installer/core/managers/go/init.lua
@@ -12,7 +12,7 @@ function M.packages(packages)
     ---@param ctx InstallContext
     return function(ctx)
         local env = process.graft_env {
-            GOBIN = ctx.cwd(),
+            GOBIN = ctx.cwd:get(),
         }
         -- Install the head package
         do
diff --git a/lua/nvim-lsp-installer/core/managers/pip3/init.lua b/lua/nvim-lsp-installer/core/managers/pip3/init.lua
index 61130a96..06408f3b 100644
--- a/lua/nvim-lsp-installer/core/managers/pip3/init.lua
+++ b/lua/nvim-lsp-installer/core/managers/pip3/init.lua
@@ -32,7 +32,7 @@ function M.packages(packages)
             or list_not_nil(vim.g.python3_host_prog, "python3", "python")
 
         -- pip3 will hardcode the full path to venv executables, so we need to promote cwd to make sure pip uses the final destination path.
-        ctx:promote_cwd():get_or_throw()
+        ctx:promote_cwd()
 
         -- Find first executable that manages to create venv
         local executable = list_find_first(executables, function(executable)
@@ -42,7 +42,7 @@ function M.packages(packages)
         Optional.of_nilable(executable)
             :if_present(function(python3)
                 ctx.spawn[python3] {
-                    env = process.graft_env(M.env(ctx:cwd())), -- use venv env
+                    env = process.graft_env(M.env(ctx.cwd:get())), -- use venv env
                     "-m",
                     "pip",
                     "install",
diff --git a/lua/nvim-lsp-installer/core/optional.lua b/lua/nvim-lsp-installer/core/optional.lua
index d37a7e69..8e68648c 100644
--- a/lua/nvim-lsp-installer/core/optional.lua
+++ b/lua/nvim-lsp-installer/core/optional.lua
@@ -54,9 +54,9 @@ function Optional:or_else(value)
 end
 
 ---@param supplier fun(): Optional
-function Optional:when_empty(supplier)
+function Optional:or_(supplier)
     if self:is_present() then
-        return self._value
+        return self
     else
         return supplier()
     end
diff --git a/lua/nvim-lsp-installer/core/result.lua b/lua/nvim-lsp-installer/core/result.lua
index f5c2d747..74fb9bc8 100644
--- a/lua/nvim-lsp-installer/core/result.lua
+++ b/lua/nvim-lsp-installer/core/result.lua
@@ -113,6 +113,22 @@ function Result:recover_catching(recover_fn)
     end
 end
 
+---@param fn fun(value: any): any
+function Result:on_failure(fn)
+    if self:is_failure() then
+        fn(self.value.error)
+    end
+    return self
+end
+
+---@param fn fun(value: any): any
+function Result:on_success(fn)
+    if self:is_success() then
+        fn(self.value)
+    end
+    return self
+end
+
 ---@param fn fun(): any
 ---@return Result
 function Result.run_catching(fn)
diff --git a/lua/nvim-lsp-installer/health/init.lua b/lua/nvim-lsp-installer/health/init.lua
index 0db06461..44a0cdc4 100644
--- a/lua/nvim-lsp-installer/health/init.lua
+++ b/lua/nvim-lsp-installer/health/init.lua
@@ -1,13 +1,14 @@
 local health = require "health"
 local process = require "nvim-lsp-installer.process"
-local gem = require "nvim-lsp-installer.installers.gem"
-local composer = require "nvim-lsp-installer.installers.composer"
-local npm = require "nvim-lsp-installer.installers.npm"
 local platform = require "nvim-lsp-installer.platform"
 local Data = require "nvim-lsp-installer.data"
 
 local when = Data.when
 
+local gem_cmd = platform.is_win and "gem.cmd" or "gem"
+local composer_cmd = platform.is_win and "composer.bat" or "composer"
+local npm_cmd = platform.is_win and "npm.cmd" or "npm"
+
 local M = {}
 
 ---@alias HealthCheckResult
@@ -156,11 +157,11 @@ function M.check()
             end,
         },
         check { cmd = "ruby", args = { "--version" }, name = "Ruby", relaxed = true },
-        check { cmd = gem.gem_cmd, args = { "--version" }, name = "RubyGem", relaxed = true },
-        check { cmd = composer.composer_cmd, args = { "--version" }, name = "Composer", relaxed = true },
+        check { cmd = gem_cmd, args = { "--version" }, name = "RubyGem", relaxed = true },
+        check { cmd = composer_cmd, args = { "--version" }, name = "Composer", relaxed = true },
         check { cmd = "php", args = { "--version" }, name = "PHP", relaxed = true },
         check {
-            cmd = npm.npm_command,
+            cmd = npm_cmd,
             args = { "--version" },
             name = "npm",
             version_check = function(version)
diff --git a/lua/nvim-lsp-installer/server.lua b/lua/nvim-lsp-installer/server.lua
index 5597bba7..de6481a4 100644
--- a/lua/nvim-lsp-installer/server.lua
+++ b/lua/nvim-lsp-installer/server.lua
@@ -1,14 +1,17 @@
 local dispatcher = require "nvim-lsp-installer.dispatcher"
 local a = require "nvim-lsp-installer.core.async"
+local InstallContext = require "nvim-lsp-installer.core.installer.context"
 local fs = require "nvim-lsp-installer.fs"
 local log = require "nvim-lsp-installer.log"
 local platform = require "nvim-lsp-installer.platform"
 local settings = require "nvim-lsp-installer.settings"
 local installers = require "nvim-lsp-installer.installers"
+local installer = require "nvim-lsp-installer.core.installer"
 local servers = require "nvim-lsp-installer.servers"
 local status_win = require "nvim-lsp-installer.ui.status-win"
 local path = require "nvim-lsp-installer.path"
 local receipt = require "nvim-lsp-installer.core.receipt"
+local Optional = require "nvim-lsp-installer.core.optional"
 
 local M = {}
 
@@ -25,6 +28,7 @@ M.get_server_root_path = servers.get_server_install_path
 ---@field public  deprecated ServerDeprecation|nil @The existence (not nil) of this field indicates this server is depracted.
 ---@field public  languages string[]
 ---@field private _installer ServerInstallerFunction
+---@field private _async boolean
 ---@field private _on_ready_handlers fun(server: Server)[]
 ---@field private _default_options table @The server's default options. This is used in @see Server#setup.
 M.Server = {}
@@ -38,9 +42,10 @@ function M.Server:new(opts)
         root_dir = opts.root_dir,
         homepage = opts.homepage,
         deprecated = opts.deprecated,
+        _async = opts.async or false,
         languages = opts.languages or {},
         _on_ready_handlers = {},
-        _installer = type(opts.installer) == "function" and opts.installer or installers.pipe(opts.installer),
+        _installer = opts.installer,
         _default_options = opts.default_options,
     }, M.Server)
 end
@@ -208,47 +213,68 @@ end
 ---@param context ServerInstallContext
 ---@param callback ServerInstallCallback
 function M.Server:install_attached(context, callback)
-    a.run(
-        function()
-            context.receipt = receipt.InstallReceiptBuilder.new()
-            context.receipt:with_start_time(vim.loop.gettimeofday())
-
-            a.scheduler()
-            self:_setup_install_context(context)
-            local async_installer = a.promisify(function(server, context, callback)
-                -- args are shifted
-                return self._installer(server, callback, context)
-            end)
-            assert(async_installer(self, context), "Installation failed.")
-
+    if self._async then
+        a.run(function()
+            local install_context = InstallContext.new {
+                name = self.name,
+                boundary_path = settings.current.install_root_dir,
+                stdio_sink = context.stdio_sink,
+                destination_dir = self.root_dir,
+                requested_version = Optional.of_nilable(context.requested_server_version),
+            }
+            installer.execute(install_context, self._installer):get_or_throw()
             a.scheduler()
-            if not self:promote_install_dir(context.install_dir) then
-                error(("Failed to promote the temporary installation directory %q."):format(context.install_dir))
+            dispatcher.dispatch_server_ready(self)
+            for _, on_ready_handler in ipairs(self._on_ready_handlers) do
+                on_ready_handler(self)
             end
+        end, callback)
+    else
+        --- Deprecated
+        a.run(
+            function()
+                context.receipt = receipt.InstallReceiptBuilder.new()
+                context.receipt:with_start_time(vim.loop.gettimeofday())
 
-            self:_write_receipt(context.receipt)
+                a.scheduler()
+                self:_setup_install_context(context)
+                local async_installer = a.promisify(function(server, context, callback)
+                    local normalized_installer = type(self._installer) == "function" and self._installer
+                        or installers.pipe(self._installer)
+                    -- args are shifted
+                    return normalized_installer(server, callback, context)
+                end)
+                assert(async_installer(self, context), "Installation failed.")
 
-            -- Dispatch the server is ready
-            vim.schedule(function()
-                dispatcher.dispatch_server_ready(self)
-                for _, on_ready_handler in ipairs(self._on_ready_handlers) do
-                    on_ready_handler(self)
+                a.scheduler()
+                if not self:promote_install_dir(context.install_dir) then
+                    error(("Failed to promote the temporary installation directory %q."):format(context.install_dir))
                 end
+
+                self:_write_receipt(context.receipt)
+
+                -- Dispatch the server is ready
+                vim.schedule(function()
+                    dispatcher.dispatch_server_ready(self)
+                    for _, on_ready_handler in ipairs(self._on_ready_handlers) do
+                        on_ready_handler(self)
+                    end
+                end)
+            end,
+            vim.schedule_wrap(function(ok, result)
+                if not ok then
+                    pcall(fs.rmrf, context.install_dir)
+                    log.fmt_error("Server installation failed, server_name=%s, error=%s", self.name, result)
+                    context.stdio_sink.stderr(tostring(result) .. "\n")
+                end
+                -- The tmp dir should in most cases have been "promoted" and already renamed to its final destination,
+                -- but we make sure to delete it should the installer modify the installation working directory during
+                -- installation.
+                pcall(fs.rmrf, self:get_tmp_install_dir())
+                callback(ok)
             end)
-        end,
-        vim.schedule_wrap(function(ok, result)
-            if not ok then
-                pcall(fs.rmrf, context.install_dir)
-                log.fmt_error("Server installation failed, server_name=%s, error=%s", self.name, result)
-                context.stdio_sink.stderr(tostring(result) .. "\n")
-            end
-            -- The tmp dir should in most cases have been "promoted" and already renamed to its final destination,
-            -- but we make sure to delete it should the installer modify the installation working directory during
-            -- installation.
-            pcall(fs.rmrf, self:get_tmp_install_dir())
-            callback(ok)
-        end)
-    )
+        )
+    end
 end
 
 function M.Server:uninstall()
diff --git a/lua/nvim-lsp-installer/servers/angularls/init.lua b/lua/nvim-lsp-installer/servers/angularls/init.lua
index feb31190..23970b25 100644
--- a/lua/nvim-lsp-installer/servers/angularls/init.lua
+++ b/lua/nvim-lsp-installer/servers/angularls/init.lua
@@ -1,6 +1,6 @@
 local server = require "nvim-lsp-installer.server"
 local platform = require "nvim-lsp-installer.platform"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 local Data = require "nvim-lsp-installer.data"
 local path = require "nvim-lsp-installer.path"
 
@@ -42,6 +42,7 @@ return function(name, root_dir)
         homepage = "https://angular.io/guide/language-service",
         languages = { "angular" },
         installer = npm.packages { "@angular/language-server", "typescript" },
+        async = true,
         default_options = {
             cmd = get_cmd(path.cwd()),
             cmd_env = npm.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/ansiblels/init.lua b/lua/nvim-lsp-installer/servers/ansiblels/init.lua
index 2ee54b65..92541e56 100644
--- a/lua/nvim-lsp-installer/servers/ansiblels/init.lua
+++ b/lua/nvim-lsp-installer/servers/ansiblels/init.lua
@@ -1,8 +1,8 @@
 local server = require "nvim-lsp-installer.server"
 local path = require "nvim-lsp-installer.path"
-local std = require "nvim-lsp-installer.installers.std"
-local npm = require "nvim-lsp-installer.installers.npm"
-local context = require "nvim-lsp-installer.installers.context"
+local npm = require "nvim-lsp-installer.core.managers.npm"
+local git = require "nvim-lsp-installer.core.managers.git"
+local installer = require "nvim-lsp-installer.core.installer"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -10,14 +10,13 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "ansible" },
         homepage = "https://github.com/ansible/ansible-language-server",
-        installer = {
-            std.git_clone "https://github.com/ansible/ansible-language-server",
-            npm.install { "npm@latest" }, -- ansiblels has quite a strict npm version requirement
-            npm.exec(npm.npm_command, { "install" }),
-            npm.run "compile",
-            context.receipt(function(receipt)
-                receipt:with_primary_source(receipt.git_remote "https://github.com/ansible/ansible-language-server")
-            end),
+        async = true,
+        installer = installer.serial {
+            git.clone { "https://github.com/ansible/ansible-language-server" },
+            -- ansiblels has quite a strict npm version requirement.
+            -- Install dependencies using the the latest npm version.
+            npm.exec { "npm@latest", "install" },
+            npm.run { "compile" },
         },
         default_options = {
             cmd = { "node", path.concat { root_dir, "out", "server", "src", "server.js" }, "--stdio" },
diff --git a/lua/nvim-lsp-installer/servers/asm_lsp/init.lua b/lua/nvim-lsp-installer/servers/asm_lsp/init.lua
index 35f3ab92..f80f8401 100644
--- a/lua/nvim-lsp-installer/servers/asm_lsp/init.lua
+++ b/lua/nvim-lsp-installer/servers/asm_lsp/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local cargo = require "nvim-lsp-installer.installers.cargo"
+local cargo = require "nvim-lsp-installer.core.managers.cargo"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "assembly-gas", "assembly-nasm", "assembly-go" },
         homepage = "https://github.com/bergercookie/asm-lsp",
+        async = true,
         installer = cargo.crate "asm-lsp",
         default_options = {
             cmd_env = cargo.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/awk_ls/init.lua b/lua/nvim-lsp-installer/servers/awk_ls/init.lua
index 62695777..213abaca 100644
--- a/lua/nvim-lsp-installer/servers/awk_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/awk_ls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "awk" },
         homepage = "https://github.com/Beaglefoot/awk-language-server",
         installer = npm.packages { "awk-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/bashls/init.lua b/lua/nvim-lsp-installer/servers/bashls/init.lua
index e8a2553e..bb3e5d53 100644
--- a/lua/nvim-lsp-installer/servers/bashls/init.lua
+++ b/lua/nvim-lsp-installer/servers/bashls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "bash" },
         homepage = "https://github.com/bash-lsp/bash-language-server",
+        async = true,
         installer = npm.packages { "bash-language-server" },
         default_options = {
             cmd_env = npm.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/cmake/init.lua b/lua/nvim-lsp-installer/servers/cmake/init.lua
index f70624cb..f6c3058a 100644
--- a/lua/nvim-lsp-installer/servers/cmake/init.lua
+++ b/lua/nvim-lsp-installer/servers/cmake/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local pip3 = require "nvim-lsp-installer.installers.pip3"
+local pip3 = require "nvim-lsp-installer.core.managers.pip3"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         homepage = "https://github.com/regen100/cmake-language-server",
         languages = { "cmake" },
+        async = true,
         installer = pip3.packages { "cmake-language-server" },
         default_options = {
             cmd_env = pip3.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/csharp_ls/init.lua b/lua/nvim-lsp-installer/servers/csharp_ls/init.lua
index 82ad4258..8600782d 100644
--- a/lua/nvim-lsp-installer/servers/csharp_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/csharp_ls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local dotnet = require "nvim-lsp-installer.installers.dotnet"
+local dotnet = require "nvim-lsp-installer.core.managers.dotnet"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "c#" },
         homepage = "https://github.com/razzmatazz/csharp-language-server",
+        async = true,
         installer = dotnet.package "csharp-ls",
         default_options = {
             cmd_env = dotnet.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/cssmodules_ls/init.lua b/lua/nvim-lsp-installer/servers/cssmodules_ls/init.lua
index b1a6c188..cf09539f 100644
--- a/lua/nvim-lsp-installer/servers/cssmodules_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/cssmodules_ls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/antonk52/cssmodules-language-server",
         languages = { "css" },
         installer = npm.packages { "cssmodules-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/cucumber_language_server/init.lua b/lua/nvim-lsp-installer/servers/cucumber_language_server/init.lua
index d9b091db..3d810f01 100644
--- a/lua/nvim-lsp-installer/servers/cucumber_language_server/init.lua
+++ b/lua/nvim-lsp-installer/servers/cucumber_language_server/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "cucumber" },
         homepage = "https://github.com/cucumber/language-server",
         installer = npm.packages { "@cucumber/language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/diagnosticls/init.lua b/lua/nvim-lsp-installer/servers/diagnosticls/init.lua
index 5594eca2..9b822a2b 100644
--- a/lua/nvim-lsp-installer/servers/diagnosticls/init.lua
+++ b/lua/nvim-lsp-installer/servers/diagnosticls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = {},
         homepage = "https://github.com/iamcco/diagnostic-languageserver",
         installer = npm.packages { "diagnostic-languageserver" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/dockerls/init.lua b/lua/nvim-lsp-installer/servers/dockerls/init.lua
index ab306ff2..45ce6806 100644
--- a/lua/nvim-lsp-installer/servers/dockerls/init.lua
+++ b/lua/nvim-lsp-installer/servers/dockerls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/rcjsuen/dockerfile-language-server-nodejs",
         languages = { "docker" },
         installer = npm.packages { "dockerfile-language-server-nodejs" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/dotls/init.lua b/lua/nvim-lsp-installer/servers/dotls/init.lua
index b4655e52..26400b65 100644
--- a/lua/nvim-lsp-installer/servers/dotls/init.lua
+++ b/lua/nvim-lsp-installer/servers/dotls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/nikeee/dot-language-server",
         languages = { "dot" },
         installer = npm.packages { "dot-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/elmls/init.lua b/lua/nvim-lsp-installer/servers/elmls/init.lua
index 8d5e0041..30eebfd3 100644
--- a/lua/nvim-lsp-installer/servers/elmls/init.lua
+++ b/lua/nvim-lsp-installer/servers/elmls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/elm-tooling/elm-language-server",
         languages = { "elm" },
         installer = npm.packages { "@elm-tooling/elm-language-server", "elm", "elm-test", "elm-format" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/ember/init.lua b/lua/nvim-lsp-installer/servers/ember/init.lua
index 80c417b6..3ebddec9 100644
--- a/lua/nvim-lsp-installer/servers/ember/init.lua
+++ b/lua/nvim-lsp-installer/servers/ember/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "ember" },
         homepage = "https://github.com/lifeart/ember-language-server",
         installer = npm.packages { "@lifeart/ember-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/emmet_ls/init.lua b/lua/nvim-lsp-installer/servers/emmet_ls/init.lua
index 93fa181c..91258daa 100644
--- a/lua/nvim-lsp-installer/servers/emmet_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/emmet_ls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/aca/emmet-ls",
         languages = { "emmet" },
         installer = npm.packages { "emmet-ls" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/esbonio/init.lua b/lua/nvim-lsp-installer/servers/esbonio/init.lua
index 173eb44c..b0de81d7 100644
--- a/lua/nvim-lsp-installer/servers/esbonio/init.lua
+++ b/lua/nvim-lsp-installer/servers/esbonio/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local pip3 = require "nvim-lsp-installer.installers.pip3"
+local pip3 = require "nvim-lsp-installer.core.managers.pip3"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "sphinx" },
         homepage = "https://pypi.org/project/esbonio/",
+        async = true,
         installer = pip3.packages { "esbonio" },
         default_options = {
             cmd_env = pip3.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/flux_lsp/init.lua b/lua/nvim-lsp-installer/servers/flux_lsp/init.lua
index 0475528f..be9ffce5 100644
--- a/lua/nvim-lsp-installer/servers/flux_lsp/init.lua
+++ b/lua/nvim-lsp-installer/servers/flux_lsp/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local cargo = require "nvim-lsp-installer.installers.cargo"
+local cargo = require "nvim-lsp-installer.core.managers.cargo"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "flux" },
         homepage = "https://github.com/influxdata/flux-lsp",
+        async = true,
         installer = cargo.crate("https://github.com/influxdata/flux-lsp", {
             git = true,
         }),
diff --git a/lua/nvim-lsp-installer/servers/foam_ls/init.lua b/lua/nvim-lsp-installer/servers/foam_ls/init.lua
index 2e28fe08..2586b242 100644
--- a/lua/nvim-lsp-installer/servers/foam_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/foam_ls/init.lua
@@ -1,6 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local path = require "nvim-lsp-installer.path"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -9,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/FoamScience/foam-language-server",
         languages = { "foam", "OpenFOAM" },
         installer = npm.packages { "foam-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/fortls/init.lua b/lua/nvim-lsp-installer/servers/fortls/init.lua
index aade0502..466dc910 100644
--- a/lua/nvim-lsp-installer/servers/fortls/init.lua
+++ b/lua/nvim-lsp-installer/servers/fortls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local pip3 = require "nvim-lsp-installer.installers.pip3"
+local pip3 = require "nvim-lsp-installer.core.managers.pip3"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         homepage = "https://github.com/hansec/fortran-language-server",
         languages = { "fortran" },
+        async = true,
         installer = pip3.packages { "fortran-language-server" },
         default_options = {
             cmd_env = pip3.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/fsautocomplete/init.lua b/lua/nvim-lsp-installer/servers/fsautocomplete/init.lua
index cd1284e7..fd075ba7 100644
--- a/lua/nvim-lsp-installer/servers/fsautocomplete/init.lua
+++ b/lua/nvim-lsp-installer/servers/fsautocomplete/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local dotnet = require "nvim-lsp-installer.installers.dotnet"
+local dotnet = require "nvim-lsp-installer.core.managers.dotnet"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "f#" },
         homepage = "https://github.com/fsharp/FsAutoComplete",
+        async = true,
         installer = dotnet.package "fsautocomplete",
         default_options = {
             cmd_env = dotnet.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/grammarly/init.lua b/lua/nvim-lsp-installer/servers/grammarly/init.lua
index 1c8d7646..58c7a217 100644
--- a/lua/nvim-lsp-installer/servers/grammarly/init.lua
+++ b/lua/nvim-lsp-installer/servers/grammarly/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/znck/grammarly",
         languages = {},
         installer = npm.packages { "@emacs-grammarly/unofficial-grammarly-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/graphql/init.lua b/lua/nvim-lsp-installer/servers/graphql/init.lua
index c513208e..fe0ac0f0 100644
--- a/lua/nvim-lsp-installer/servers/graphql/init.lua
+++ b/lua/nvim-lsp-installer/servers/graphql/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://www.npmjs.com/package/graphql-language-service-cli",
         languages = { "graphql" },
         installer = npm.packages { "graphql-language-service-cli", "graphql" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/intelephense/init.lua b/lua/nvim-lsp-installer/servers/intelephense/init.lua
index a606ce35..e4e86c29 100644
--- a/lua/nvim-lsp-installer/servers/intelephense/init.lua
+++ b/lua/nvim-lsp-installer/servers/intelephense/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://intelephense.com",
         languages = { "php" },
         installer = npm.packages { "intelephense" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/jedi_language_server/init.lua b/lua/nvim-lsp-installer/servers/jedi_language_server/init.lua
index 2a7b300a..86c4ebe1 100644
--- a/lua/nvim-lsp-installer/servers/jedi_language_server/init.lua
+++ b/lua/nvim-lsp-installer/servers/jedi_language_server/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local pip3 = require "nvim-lsp-installer.installers.pip3"
+local pip3 = require "nvim-lsp-installer.core.managers.pip3"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "python" },
         homepage = "https://github.com/pappasam/jedi-language-server",
+        async = true,
         installer = pip3.packages { "jedi-language-server" },
         default_options = {
             cmd_env = pip3.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/lelwel_ls/init.lua b/lua/nvim-lsp-installer/servers/lelwel_ls/init.lua
index b00dbdfa..d69aedd5 100644
--- a/lua/nvim-lsp-installer/servers/lelwel_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/lelwel_ls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local cargo = require "nvim-lsp-installer.installers.cargo"
+local cargo = require "nvim-lsp-installer.core.managers.cargo"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "lelwel" },
         homepage = "https://github.com/0x2a-42/lelwel",
+        async = true,
         installer = cargo.crate("lelwel", {
             features = "lsp",
         }),
diff --git a/lua/nvim-lsp-installer/servers/nickel_ls/init.lua b/lua/nvim-lsp-installer/servers/nickel_ls/init.lua
index d87062e7..bf87cd21 100644
--- a/lua/nvim-lsp-installer/servers/nickel_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/nickel_ls/init.lua
@@ -1,8 +1,8 @@
 local path = require "nvim-lsp-installer.path"
 local server = require "nvim-lsp-installer.server"
-local std = require "nvim-lsp-installer.installers.std"
-local context = require "nvim-lsp-installer.installers.context"
-local cargo = require "nvim-lsp-installer.installers.cargo"
+local installer = require "nvim-lsp-installer.core.installer"
+local cargo = require "nvim-lsp-installer.core.managers.cargo"
+local git = require "nvim-lsp-installer.core.managers.git"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -10,14 +10,19 @@ return function(name, root_dir)
         root_dir = root_dir,
         homepage = "https://nickel-lang.org/",
         languages = { "nickel" },
-        installer = {
-            std.git_clone "https://github.com/tweag/nickel",
-            cargo.install {
-                path = path.concat { "lsp", "nls" },
-            },
-            context.receipt(function(receipt)
-                receipt:with_primary_source(receipt.git_remote "https://github.com/tweag/nickel")
-            end),
+        async = true,
+        installer = installer.serial {
+            git.clone { "https://github.com/tweag/nickel" },
+            ---@param ctx InstallContext
+            function(ctx)
+                ctx.spawn.cargo {
+                    "install",
+                    "--root",
+                    ".",
+                    "--path",
+                    path.concat { "lsp", "nls" },
+                }
+            end,
         },
         default_options = {
             cmd_env = cargo.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/ocamlls/init.lua b/lua/nvim-lsp-installer/servers/ocamlls/init.lua
index 80361b4c..062be8e7 100644
--- a/lua/nvim-lsp-installer/servers/ocamlls/init.lua
+++ b/lua/nvim-lsp-installer/servers/ocamlls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -12,6 +12,7 @@ return function(name, root_dir)
         homepage = "https://github.com/ocaml-lsp/ocaml-language-server",
         languages = { "ocaml" },
         installer = npm.packages { "ocaml-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/ocamllsp/init.lua b/lua/nvim-lsp-installer/servers/ocamllsp/init.lua
index 73b6bab8..ad51cfa4 100644
--- a/lua/nvim-lsp-installer/servers/ocamllsp/init.lua
+++ b/lua/nvim-lsp-installer/servers/ocamllsp/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local opam = require "nvim-lsp-installer.installers.opam"
+local opam = require "nvim-lsp-installer.core.managers.opam"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         homepage = "https://github.com/ocaml/ocaml-lsp",
         languages = { "ocaml" },
+        async = true,
         installer = opam.packages { "ocaml-lsp-server" },
         default_options = {
             cmd_env = opam.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/perlnavigator/init.lua b/lua/nvim-lsp-installer/servers/perlnavigator/init.lua
index c944eeb9..fc82fe3c 100644
--- a/lua/nvim-lsp-installer/servers/perlnavigator/init.lua
+++ b/lua/nvim-lsp-installer/servers/perlnavigator/init.lua
@@ -1,6 +1,6 @@
 local server = require "nvim-lsp-installer.server"
 local path = require "nvim-lsp-installer.path"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -9,6 +9,7 @@ return function(name, root_dir)
         languages = { "perl" },
         homepage = "https://github.com/bscan/PerlNavigator",
         installer = npm.packages { "perlnavigator-server" },
+        async = true,
         default_options = {
             cmd = {
                 "node",
diff --git a/lua/nvim-lsp-installer/servers/phpactor/init.lua b/lua/nvim-lsp-installer/servers/phpactor/init.lua
index 45ce5ccd..af5d863c 100644
--- a/lua/nvim-lsp-installer/servers/phpactor/init.lua
+++ b/lua/nvim-lsp-installer/servers/phpactor/init.lua
@@ -1,10 +1,10 @@
-local installers = require "nvim-lsp-installer.installers"
 local path = require "nvim-lsp-installer.path"
 local server = require "nvim-lsp-installer.server"
-local composer = require "nvim-lsp-installer.installers.composer"
-local std = require "nvim-lsp-installer.installers.std"
-local context = require "nvim-lsp-installer.installers.context"
+local composer = require "nvim-lsp-installer.core.managers.composer"
+local git = require "nvim-lsp-installer.core.managers.git"
+local installer = require "nvim-lsp-installer.core.installer"
 local process = require "nvim-lsp-installer.process"
+local platform = require "nvim-lsp-installer.platform"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -12,14 +12,13 @@ return function(name, root_dir)
         root_dir = root_dir,
         homepage = "https://phpactor.readthedocs.io/en/master/",
         languages = { "php" },
-        installer = installers.when {
-            unix = {
-                std.git_clone "https://github.com/phpactor/phpactor.git",
-                composer.install(),
-                context.receipt(function(receipt)
-                    receipt:with_primary_source(receipt.git_remote "https://github.com/phpactor/phpactor.git")
-                end),
-            },
+        async = true,
+        installer = installer.serial {
+            function()
+                assert(platform.is_unix, "Phpactor only supports UNIX environments.")
+            end,
+            git.clone { "https://github.com/phpactor/phpactor.git" },
+            composer.install(),
         },
         default_options = {
             cmd_env = {
diff --git a/lua/nvim-lsp-installer/servers/prismals/init.lua b/lua/nvim-lsp-installer/servers/prismals/init.lua
index e7e38391..e42aa1a1 100644
--- a/lua/nvim-lsp-installer/servers/prismals/init.lua
+++ b/lua/nvim-lsp-installer/servers/prismals/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "prisma" },
         homepage = "https://github.com/prisma/language-tools",
         installer = npm.packages { "@prisma/language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/psalm/init.lua b/lua/nvim-lsp-installer/servers/psalm/init.lua
index 3b3d4721..8c8b9be3 100644
--- a/lua/nvim-lsp-installer/servers/psalm/init.lua
+++ b/lua/nvim-lsp-installer/servers/psalm/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local composer = require "nvim-lsp-installer.installers.composer"
+local composer = require "nvim-lsp-installer.core.managers.composer"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         homepage = "https://psalm.dev/",
         languages = { "php" },
+        async = true,
         installer = composer.require { "vimeo/psalm" },
         default_options = {
             cmd_env = composer.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/purescriptls/init.lua b/lua/nvim-lsp-installer/servers/purescriptls/init.lua
index 710d6d47..338bb82c 100644
--- a/lua/nvim-lsp-installer/servers/purescriptls/init.lua
+++ b/lua/nvim-lsp-installer/servers/purescriptls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "purescript" },
         homepage = "https://github.com/nwolverson/purescript-language-server",
         installer = npm.packages { "purescript-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/pylsp/init.lua b/lua/nvim-lsp-installer/servers/pylsp/init.lua
index a676109b..0ee9e6a0 100644
--- a/lua/nvim-lsp-installer/servers/pylsp/init.lua
+++ b/lua/nvim-lsp-installer/servers/pylsp/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local pip3 = require "nvim-lsp-installer.installers.pip3"
+local pip3 = require "nvim-lsp-installer.core.managers.pip3"
 local process = require "nvim-lsp-installer.process"
 local notify = require "nvim-lsp-installer.notify"
 
@@ -21,6 +21,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "python" },
         homepage = "https://github.com/python-lsp/python-lsp-server",
+        async = true,
         installer = pip3.packages { "python-lsp-server[all]" },
         default_options = {
             cmd_env = pip3.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/pyright/init.lua b/lua/nvim-lsp-installer/servers/pyright/init.lua
index 8bdcaebd..73c6bed3 100644
--- a/lua/nvim-lsp-installer/servers/pyright/init.lua
+++ b/lua/nvim-lsp-installer/servers/pyright/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "python" },
         homepage = "https://github.com/microsoft/pyright",
         installer = npm.packages { "pyright" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/remark_ls/init.lua b/lua/nvim-lsp-installer/servers/remark_ls/init.lua
index 860b2db1..acc7c2f3 100644
--- a/lua/nvim-lsp-installer/servers/remark_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/remark_ls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/remarkjs/remark-language-server",
         languages = { "markdown" },
         installer = npm.packages { "remark-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/rnix/init.lua b/lua/nvim-lsp-installer/servers/rnix/init.lua
index 35290aae..d552b11c 100644
--- a/lua/nvim-lsp-installer/servers/rnix/init.lua
+++ b/lua/nvim-lsp-installer/servers/rnix/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local cargo = require "nvim-lsp-installer.installers.cargo"
+local cargo = require "nvim-lsp-installer.core.managers.cargo"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "nix" },
         homepage = "https://github.com/nix-community/rnix-lsp",
+        async = true,
         installer = cargo.crate "rnix-lsp",
         default_options = {
             cmd_env = cargo.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/rome/init.lua b/lua/nvim-lsp-installer/servers/rome/init.lua
index ca1f25bf..7a20384c 100644
--- a/lua/nvim-lsp-installer/servers/rome/init.lua
+++ b/lua/nvim-lsp-installer/servers/rome/init.lua
@@ -1,7 +1,7 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
-local Data = require "nvim-lsp-installer.data"
-local context = require "nvim-lsp-installer.installers.context"
+local npm = require "nvim-lsp-installer.core.managers.npm"
+local installer = require "nvim-lsp-installer.core.installer"
+local Optional = require "nvim-lsp-installer.core.optional"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -9,15 +9,16 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "typescript", "javascript" },
         homepage = "https://rome.tools",
-        installer = {
-            context.set(function(ctx)
-                ctx.requested_server_version = Data.coalesce(
-                    ctx.requested_server_version,
-                    "10.0.7-nightly.2021.7.27" -- https://github.com/rome/tools/pull/1409
-                )
-            end),
+        installer = installer.serial {
+            ---@param ctx InstallContext
+            function(ctx)
+                ctx.requested_version = ctx.requested_version:or_(function()
+                    return Optional.of "10.0.7-nightly.2021.7.27"
+                end)
+            end,
             npm.packages { "rome" },
         },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/salt_ls/init.lua b/lua/nvim-lsp-installer/servers/salt_ls/init.lua
index 8101fa2e..f8d27a7e 100644
--- a/lua/nvim-lsp-installer/servers/salt_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/salt_ls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local pip3 = require "nvim-lsp-installer.installers.pip3"
+local pip3 = require "nvim-lsp-installer.core.managers.pip3"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "sls" },
         homepage = "https://github.com/dcermak/salt-lsp",
+        async = true,
         installer = pip3.packages { "salt-lsp" },
         default_options = {
             cmd_env = pip3.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/solidity_ls/init.lua b/lua/nvim-lsp-installer/servers/solidity_ls/init.lua
index 451738f6..577b5c35 100644
--- a/lua/nvim-lsp-installer/servers/solidity_ls/init.lua
+++ b/lua/nvim-lsp-installer/servers/solidity_ls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "solidity" },
         homepage = "https://github.com/edag94/vscode-solidity",
         installer = npm.packages { "solidity-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/sqlls/init.lua b/lua/nvim-lsp-installer/servers/sqlls/init.lua
index 7e6e0dff..3e562608 100644
--- a/lua/nvim-lsp-installer/servers/sqlls/init.lua
+++ b/lua/nvim-lsp-installer/servers/sqlls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "sql" },
         homepage = "https://github.com/joe-re/sql-language-server",
         installer = npm.packages { "sql-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/stylelint_lsp/init.lua b/lua/nvim-lsp-installer/servers/stylelint_lsp/init.lua
index 1bfbe7f3..6d52b3b2 100644
--- a/lua/nvim-lsp-installer/servers/stylelint_lsp/init.lua
+++ b/lua/nvim-lsp-installer/servers/stylelint_lsp/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         homepage = "https://github.com/bmatcuk/stylelint-lsp",
         languages = { "stylelint" },
         installer = npm.packages { "stylelint-lsp" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/svelte/init.lua b/lua/nvim-lsp-installer/servers/svelte/init.lua
index b14dc247..3cc545b0 100644
--- a/lua/nvim-lsp-installer/servers/svelte/init.lua
+++ b/lua/nvim-lsp-installer/servers/svelte/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "svelte" },
         homepage = "https://github.com/sveltejs/language-tools",
         installer = npm.packages { "svelte-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/svls/init.lua b/lua/nvim-lsp-installer/servers/svls/init.lua
index 401ee965..58a46432 100644
--- a/lua/nvim-lsp-installer/servers/svls/init.lua
+++ b/lua/nvim-lsp-installer/servers/svls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local cargo = require "nvim-lsp-installer.installers.cargo"
+local cargo = require "nvim-lsp-installer.core.managers.cargo"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "systemverilog" },
         homepage = "https://github.com/dalance/svls",
+        async = true,
         installer = cargo.crate "svls",
         default_options = {
             cmd_env = cargo.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/tailwindcss/init.lua b/lua/nvim-lsp-installer/servers/tailwindcss/init.lua
index d62e70bd..d24948b0 100644
--- a/lua/nvim-lsp-installer/servers/tailwindcss/init.lua
+++ b/lua/nvim-lsp-installer/servers/tailwindcss/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "tailwind" },
         installer = npm.packages { "@tailwindcss/language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/taplo/init.lua b/lua/nvim-lsp-installer/servers/taplo/init.lua
index 94ddcc62..0d584e6b 100644
--- a/lua/nvim-lsp-installer/servers/taplo/init.lua
+++ b/lua/nvim-lsp-installer/servers/taplo/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local cargo = require "nvim-lsp-installer.installers.cargo"
+local cargo = require "nvim-lsp-installer.core.managers.cargo"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -7,6 +7,7 @@ return function(name, root_dir)
         root_dir = root_dir,
         languages = { "toml" },
         homepage = "https://taplo.tamasfe.dev/lsp/",
+        async = true,
         installer = cargo.crate "taplo-cli",
         default_options = {
             cmd_env = cargo.env(root_dir),
diff --git a/lua/nvim-lsp-installer/servers/tsserver/init.lua b/lua/nvim-lsp-installer/servers/tsserver/init.lua
index 5b192475..22091418 100644
--- a/lua/nvim-lsp-installer/servers/tsserver/init.lua
+++ b/lua/nvim-lsp-installer/servers/tsserver/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "typescript", "javascript" },
         homepage = "https://github.com/typescript-language-server/typescript-language-server",
         installer = npm.packages { "typescript-language-server", "typescript" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/vimls/init.lua b/lua/nvim-lsp-installer/servers/vimls/init.lua
index 28c7d26b..b753e92a 100644
--- a/lua/nvim-lsp-installer/servers/vimls/init.lua
+++ b/lua/nvim-lsp-installer/servers/vimls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "vim" },
         homepage = "https://github.com/iamcco/vim-language-server",
         installer = npm.packages { "vim-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/volar/init.lua b/lua/nvim-lsp-installer/servers/volar/init.lua
index 769689b4..4bdda7b0 100644
--- a/lua/nvim-lsp-installer/servers/volar/init.lua
+++ b/lua/nvim-lsp-installer/servers/volar/init.lua
@@ -1,7 +1,7 @@
 local path = require "nvim-lsp-installer.path"
 local fs = require "nvim-lsp-installer.fs"
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     ---@param dir string
@@ -26,6 +26,7 @@ return function(name, root_dir)
         homepage = "https://github.com/johnsoncodehk/volar",
         languages = { "vue" },
         installer = npm.packages { "@volar/vue-language-server", "typescript" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
             on_new_config = function(new_config, new_root_dir)
diff --git a/lua/nvim-lsp-installer/servers/vscode-langservers-extracted/init.lua b/lua/nvim-lsp-installer/servers/vscode-langservers-extracted/init.lua
index 83493834..22c2b045 100644
--- a/lua/nvim-lsp-installer/servers/vscode-langservers-extracted/init.lua
+++ b/lua/nvim-lsp-installer/servers/vscode-langservers-extracted/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 ---@param languages string[]
 return function(languages)
@@ -9,6 +9,7 @@ return function(languages)
             languages = languages,
             root_dir = root_dir,
             installer = npm.packages { "vscode-langservers-extracted" },
+            async = true,
             default_options = {
                 cmd_env = npm.env(root_dir),
             },
diff --git a/lua/nvim-lsp-installer/servers/vuels/init.lua b/lua/nvim-lsp-installer/servers/vuels/init.lua
index 19f19faf..4b630142 100644
--- a/lua/nvim-lsp-installer/servers/vuels/init.lua
+++ b/lua/nvim-lsp-installer/servers/vuels/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "vue" },
         homepage = "https://github.com/vuejs/vetur",
         installer = npm.packages { "vls" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/lua/nvim-lsp-installer/servers/yamlls/init.lua b/lua/nvim-lsp-installer/servers/yamlls/init.lua
index 648b5a57..bbd94e0c 100644
--- a/lua/nvim-lsp-installer/servers/yamlls/init.lua
+++ b/lua/nvim-lsp-installer/servers/yamlls/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local npm = require "nvim-lsp-installer.installers.npm"
+local npm = require "nvim-lsp-installer.core.managers.npm"
 
 return function(name, root_dir)
     return server.Server:new {
@@ -8,6 +8,7 @@ return function(name, root_dir)
         languages = { "yaml" },
         homepage = "https://github.com/redhat-developer/yaml-language-server",
         installer = npm.packages { "yaml-language-server" },
+        async = true,
         default_options = {
             cmd_env = npm.env(root_dir),
         },
diff --git a/tests/core/installer_spec.lua b/tests/core/installer_spec.lua
new file mode 100644
index 00000000..7bddaee6
--- /dev/null
+++ b/tests/core/installer_spec.lua
@@ -0,0 +1,88 @@
+local spy = require "luassert.spy"
+local match = require "luassert.match"
+local fs = require "nvim-lsp-installer.core.fs"
+local installer = require "nvim-lsp-installer.core.installer"
+local InstallContext = require "nvim-lsp-installer.core.installer.context"
+local process = require "nvim-lsp-installer.process"
+local Optional = require "nvim-lsp-installer.core.optional"
+
+describe("installer", function()
+    it(
+        "should call installer",
+        async_test(function()
+            spy.on(fs, "mkdirp")
+            spy.on(fs, "rename")
+            local installer_fn = spy.new(
+                ---@param c InstallContext
+                function(c)
+                    c.receipt:with_primary_source(c.receipt.npm "the-pkg")
+                end
+            )
+            local destination_dir = ("%s/installer_spec"):format(os.getenv "INSTALL_ROOT_DIR")
+            local ctx = InstallContext.new {
+                name = "installer_spec_success",
+                destination_dir = destination_dir,
+                boundary_path = os.getenv "INSTALL_ROOT_DIR",
+                stdio_sink = process.empty_sink(),
+                requested_version = Optional.empty(),
+            }
+            local result = installer.execute(ctx, installer_fn)
+            assert.is_nil(result:err_or_nil())
+            assert.spy(installer_fn).was_called(1)
+            assert.spy(installer_fn).was_called_with(match.ref(ctx))
+            assert.spy(fs.mkdirp).was_called(1)
+            assert.spy(fs.mkdirp).was_called_with(destination_dir .. ".tmp")
+            assert.spy(fs.rename).was_called(1)
+            assert.spy(fs.rename).was_called_with(destination_dir .. ".tmp", destination_dir)
+        end)
+    )
+
+    it(
+        "should return failure if installer errors",
+        async_test(function()
+            spy.on(fs, "rmrf")
+            local installer_fn = spy.new(function()
+                error("something went wrong. don't try again.", 4) -- 4 because spy.new callstack
+            end)
+            local destination_dir = ("%s/installer_spec_failure"):format(os.getenv "INSTALL_ROOT_DIR")
+            local ctx = InstallContext.new {
+                name = "installer_spec_failure",
+                destination_dir = destination_dir,
+                boundary_path = os.getenv "INSTALL_ROOT_DIR",
+                stdio_sink = process.empty_sink(),
+                requested_version = Optional.empty(),
+            }
+            local result = installer.execute(ctx, installer_fn)
+            assert.spy(installer_fn).was_called(1)
+            assert.spy(installer_fn).was_called_with(match.ref(ctx))
+            assert.is_true(result:is_failure())
+            assert.equals("something went wrong. don't try again.", result:err_or_nil())
+            assert.spy(fs.rmrf).was_called(2)
+            assert.spy(fs.rmrf).was_called_with(destination_dir .. ".tmp")
+            assert.spy(fs.rmrf).was_not_called_with(destination_dir)
+        end)
+    )
+
+    it(
+        "should write receipt",
+        async_test(function()
+            spy.on(fs, "write_file")
+            local destination_dir = ("%s/installer_spec_receipt"):format(os.getenv "INSTALL_ROOT_DIR")
+            local ctx = InstallContext.new {
+                name = "installer_spec_receipt",
+                destination_dir = destination_dir,
+                boundary_path = os.getenv "INSTALL_ROOT_DIR",
+                stdio_sink = process.empty_sink(),
+                requested_version = Optional.empty(),
+            }
+            installer.execute(ctx, function(c)
+                c.receipt:with_primary_source(c.receipt.npm "my-pkg")
+            end)
+            assert.spy(fs.write_file).was_called(1)
+            assert.spy(fs.write_file).was_called_with(
+                ("%s.tmp/nvim-lsp-installer-receipt.json"):format(destination_dir),
+                match.is_string()
+            )
+        end)
+    )
+end)
diff --git a/tests/core/result_spec.lua b/tests/core/result_spec.lua
index cd10acb5..97c7da06 100644
--- a/tests/core/result_spec.lua
+++ b/tests/core/result_spec.lua
@@ -1,5 +1,6 @@
 local Result = require "nvim-lsp-installer.core.result"
 local match = require "luassert.match"
+local spy = require "luassert.spy"
 
 describe("result", function()
     it("should create success", function()
@@ -117,4 +118,26 @@ describe("result", function()
         assert.is_true(result:is_failure())
         assert.equals("Oh noes", result:err_or_nil())
     end)
+
+    it("should run on_failure if failure", function()
+        local on_success = spy.new()
+        local on_failure = spy.new()
+        local result = Result.failure("Oh noes"):on_failure(on_failure):on_success(on_success)
+        assert.is_true(result:is_failure())
+        assert.equals("Oh noes", result:err_or_nil())
+        assert.spy(on_failure).was_called(1)
+        assert.spy(on_success).was_called(0)
+        assert.spy(on_failure).was_called_with "Oh noes"
+    end)
+
+    it("should run on_success if success", function()
+        local on_success = spy.new()
+        local on_failure = spy.new()
+        local result = Result.success("Oh noes"):on_failure(on_failure):on_success(on_success)
+        assert.is_true(result:is_success())
+        assert.equals("Oh noes", result:get_or_nil())
+        assert.spy(on_failure).was_called(0)
+        assert.spy(on_success).was_called(1)
+        assert.spy(on_success).was_called_with "Oh noes"
+    end)
 end)
diff --git a/tests/helpers/lua/test_helpers.lua b/tests/helpers/lua/test_helpers.lua
index 23353fcb..206337e1 100644
--- a/tests/helpers/lua/test_helpers.lua
+++ b/tests/helpers/lua/test_helpers.lua
@@ -6,7 +6,6 @@ local a = require "nvim-lsp-installer.core.async"
 local process = require "nvim-lsp-installer.process"
 local server = require "nvim-lsp-installer.server"
 local Optional = require "nvim-lsp-installer.core.optional"
-local Result = require "nvim-lsp-installer.core.result"
 local receipt = require "nvim-lsp-installer.core.receipt"
 
 function async_test(suspend_fn)
@@ -38,18 +37,18 @@ function ServerGenerator(opts)
         languages = { "dummylang" },
         root_dir = server.get_server_root_path "dummy",
         homepage = "https://dummylang.org",
-        installer = function(_, callback, ctx)
+        async = true,
+        installer = function(ctx)
             ctx.stdio_sink.stdout "Installing dummy!\n"
-            callback(true)
         end,
     }, opts))
 end
 
 function FailingServerGenerator(opts)
     return ServerGenerator(vim.tbl_deep_extend("force", {
-        installer = function(_, callback, ctx)
+        installer = function(ctx)
             ctx.stdio_sink.stdout "Installing failing dummy!\n"
-            callback(false)
+            error "Failed to do something."
         end,
     }, opts))
 end
@@ -57,16 +56,20 @@ end
 function InstallContextGenerator(opts)
     ---@type InstallContext
     local default_opts = {
+        name = "mock",
         fs = mock.new {
             append_file = mockx.just_runs,
             dir_exists = mockx.returns(true),
             file_exists = mockx.returns(true),
         },
         spawn = mock.new {},
-        cwd = function()
-            return "/tmp/install-dir"
-        end,
-        promote_cwd = mockx.returns(Result.success()),
+        cwd = mock.new {
+            get = mockx.returns "/tmp/install-dir",
+            set = mockx.just_runs,
+        },
+        destination_dir = "/opt/install-dir",
+        stdio_sink = process.empty_sink(),
+        promote_cwd = mockx.just_runs,
         receipt = receipt.InstallReceiptBuilder.new(),
         requested_version = Optional.empty(),
     }
diff --git a/tests/server_spec.lua b/tests/server_spec.lua
index 41a40750..d1ecbb6a 100644
--- a/tests/server_spec.lua
+++ b/tests/server_spec.lua
@@ -2,8 +2,6 @@ local spy = require "luassert.spy"
 local lsp_installer = require "nvim-lsp-installer"
 local server = require "nvim-lsp-installer.server"
 local a = require "nvim-lsp-installer.core.async"
-local context = require "nvim-lsp-installer.installers.context"
-local fs = require "nvim-lsp-installer.fs"
 
 local function timestamp()
     local seconds, microseconds = vim.loop.gettimeofday()
@@ -55,64 +53,27 @@ describe("server", function()
         end)
     )
 
-    -- it(
-    --     "should be able to run async installer functions",
-    --     async_test(function()
-    --         local srv = ServerGenerator {
-    --             name = "async_installer_fixture",
-    --             root_dir = server.get_server_root_path "async_installer_fixture",
-    --             async = true,
-    --             installer = function()
-    --                 a.sleep(130)
-    --             end,
-    --         }
-    --         local start = timestamp()
-    --         srv:install()
-    --         a.sleep(100)
-    --         assert.wait_for(function()
-    --             assert.is_true(srv:is_installed())
-    --         end)
-    --         local stop = timestamp()
-    --         assert.is_true(stop - start >= 100)
-    --     end)
-    -- )
-
     it(
-        "should remove directories upon installation failure",
+        "should be able to run sync installer functions",
         async_test(function()
-            local srv = FailingServerGenerator {
-                name = "remove_dirs_failure",
-                root_dir = server.get_server_root_path "remove_dirs_failure",
-                installer = {
-                    -- 1. sleep 500ms
-                    function(_, callback)
-                        vim.defer_fn(function()
-                            callback(true)
-                        end, 500)
-                    end,
-                    -- 2. promote install dir
-                    context.promote_install_dir(),
-                    -- 3. fail
-                    function(_, callback)
-                        callback(false)
-                    end,
-                },
+            local srv = ServerGenerator {
+                name = "async_installer_fixture",
+                root_dir = server.get_server_root_path "async_installer_fixture",
+                async = false,
+                installer = function(_, callback)
+                    vim.defer_fn(function()
+                        callback(true)
+                    end, 130)
+                end,
             }
+            local start = timestamp()
             srv:install()
-
-            -- 1. installation started
-            a.sleep(50)
-            assert.is_true(fs.dir_exists(srv:get_tmp_install_dir()))
-
-            -- 2. install dir promoted
-            a.sleep(500)
-            assert.is_false(fs.dir_exists(srv:get_tmp_install_dir()))
-
-            -- 3. installation failed
-            a.sleep(200)
-
-            assert.is_false(srv:is_installed())
-            assert.is_false(fs.dir_exists(srv:get_tmp_install_dir()))
+            a.sleep(100)
+            assert.wait_for(function()
+                assert.is_true(srv:is_installed())
+            end)
+            local stop = timestamp()
+            assert.is_true(stop - start >= 100)
         end)
     )
 end)