feat: allow excluding servers from automatic installation (#643)

9 files changed, 173 insertions, 12 deletions

diff --git a/README.md b/README.md
index f1804a35..c0976f8f 100644
--- a/README.md
+++ b/README.md
@@ -114,8 +114,8 @@ Example:
 
 ```lua
 require("nvim-lsp-installer").setup({
-    ensure_installed = { "rust_analyzer", "sumneko_lua" },
-    automatic_installation = true,
+    ensure_installed = { "rust_analyzer", "sumneko_lua" }, -- ensure these servers are always installed
+    automatic_installation = true, -- automatically detect which servers to install (based on which servers are set up via lspconfig)
     ui = {
         icons = {
             server_installed = "✓",
@@ -271,6 +271,11 @@ local DEFAULT_SETTINGS = {
     -- A list of servers to automatically install if they're not already installed. Example: { "rust_analyzer", "sumneko_lua" }
     ensure_installed = {},
     -- Whether servers that are set up (via lspconfig) should be automatically installed if they're not already installed.
+    -- Can either be:
+    --   - false: Servers are not automatically installed.
+    --   - true: All servers set up via lspconfig are automatically installed.
+    --   - { exclude: string[] }: All servers set up via lspconfig, except the ones provided in the list, are automatically installed.
+    --       Example: automatic_installation = { exclude = { "rust_analyzer", "solargraph" } }
     automatic_installation = false,
     ui = {
         icons = {
diff --git a/doc/nvim-lsp-installer.txt b/doc/nvim-lsp-installer.txt
index b9b05e55..68f865d8 100644
--- a/doc/nvim-lsp-installer.txt
+++ b/doc/nvim-lsp-installer.txt
@@ -158,8 +158,8 @@ Refer to the |nvim-lsp-installer-default-settings| for all available settings.
 Example: >
 
     require("nvim-lsp-installer").setup({
-        ensure_installed = { "rust_analyzer", "sumneko_lua" },
-        automatic_installation = true,
+        ensure_installed = { "rust_analyzer", "sumneko_lua" }, -- ensure these servers are always installed
+        automatic_installation = true, -- automatically detect which servers to install (based on which servers are set up via lspconfig)
         ui = {
             icons = {
                 server_installed = "✓",
@@ -177,6 +177,11 @@ The following settings are applied by default. >
         -- A list of servers to automatically install if they're not already installed. Example: { "rust_analyzer", "sumneko_lua" }
         ensure_installed = {},
         -- Whether servers that are set up (via lspconfig) should be automatically installed if they're not already installed.
+        -- Can either be:
+        --   - false: Servers are not automatically installed.
+        --   - true: All servers set up via lspconfig are automatically installed.
+        --   - { exclude: string[] }: All servers set up via lspconfig, except the ones provided in the list, are automatically installed.
+        --       Example: automatic_installation = { exclude = { "rust_analyzer", "solargraph" } }
         automatic_installation = false,
         ui = {
             icons = {
diff --git a/lua/nvim-lsp-installer/data.lua b/lua/nvim-lsp-installer/data.lua
index 264fda80..268d3aec 100644
--- a/lua/nvim-lsp-installer/data.lua
+++ b/lua/nvim-lsp-installer/data.lua
@@ -1,3 +1,5 @@
+-- TODO: rename this to functional.lua, long overdue
+
 local Data = {}
 
 ---@generic T : string
@@ -122,14 +124,16 @@ function Data.list_any(list, predicate)
     return false
 end
 
+function Data.identity(a)
+    return a
+end
+
 ---@generic T : fun(...)
 ---@param fn T
----@param cache_key_generator fun(...): string | nil
+---@param cache_key_generator (fun(...): string | nil)|nil
 ---@return T
 function Data.memoize(fn, cache_key_generator)
-    cache_key_generator = cache_key_generator or function(a)
-        return a
-    end
+    cache_key_generator = cache_key_generator or Data.identity
     local cache = {}
     return function(...)
         local key = cache_key_generator(...)
diff --git a/lua/nvim-lsp-installer/middleware.lua b/lua/nvim-lsp-installer/middleware.lua
index 7def4276..b09b51ac 100644
--- a/lua/nvim-lsp-installer/middleware.lua
+++ b/lua/nvim-lsp-installer/middleware.lua
@@ -1,6 +1,9 @@
 local util = require "lspconfig.util"
 local servers = require "nvim-lsp-installer.servers"
 local settings = require "nvim-lsp-installer.settings"
+local Data = require "nvim-lsp-installer.data"
+
+local memoize, set_of = Data.memoize, Data.set_of
 
 local M = {}
 
@@ -21,14 +24,26 @@ local function merge_in_place(t1, t2)
     return t1
 end
 
+local memoized_set = memoize(set_of)
+
+---@param server_name string
+local function should_auto_install(server_name)
+    if settings.current.automatic_installation == true then
+        return true
+    end
+    if type(settings.current.automatic_installation) == "table" then
+        return not memoized_set(settings.current.automatic_installation.exclude)[server_name]
+    end
+    return false
+end
+
 function M.register_lspconfig_hook()
     util.on_setup = util.add_hook_before(util.on_setup, function(config)
         local ok, server = servers.get_server(config.name)
         if ok then
             if server:is_installed() then
                 merge_in_place(config, server._default_options)
-            end
-            if settings.current.automatic_installation and not server:is_installed() then
+            elseif should_auto_install(server.name) then
                 server:install()
             end
         end
diff --git a/lua/nvim-lsp-installer/settings.lua b/lua/nvim-lsp-installer/settings.lua
index 44c739db..5cfdae4f 100644
--- a/lua/nvim-lsp-installer/settings.lua
+++ b/lua/nvim-lsp-installer/settings.lua
@@ -7,6 +7,11 @@ local DEFAULT_SETTINGS = {
     -- A list of servers to automatically install. Example: { "rust_analyzer", "sumneko_lua" }
     ensure_installed = {},
     -- Whether servers that are set up (via lspconfig) should be automatically installed if they're not already installed.
+    -- Can either be:
+    --   - false: Servers are not automatically installed.
+    --   - true: All servers set up via lspconfig are automatically installed.
+    --   - { exclude: string[] }: All servers set up via lspconfig, except the ones provided in the list, are automatically installed.
+    --       Example: automatic_installation = { exclude = { "rust_analyzer", "solargraph" } }
     automatic_installation = false,
     ui = {
         icons = {
diff --git a/tests/helpers/lua/test_helpers.lua b/tests/helpers/lua/test_helpers.lua
index 206337e1..a9a2426f 100644
--- a/tests/helpers/lua/test_helpers.lua
+++ b/tests/helpers/lua/test_helpers.lua
@@ -32,10 +32,11 @@ mockx = {
 }
 
 function ServerGenerator(opts)
+    local name = opts.name or "dummy"
     return server.Server:new(vim.tbl_deep_extend("force", {
-        name = "dummy",
+        name = name,
         languages = { "dummylang" },
-        root_dir = server.get_server_root_path "dummy",
+        root_dir = server.get_server_root_path(name),
         homepage = "https://dummylang.org",
         async = true,
         installer = function(ctx)
diff --git a/tests/setup/automatic_installation_exclude_spec.lua b/tests/setup/automatic_installation_exclude_spec.lua
new file mode 100644
index 00000000..bfa5c81b
--- /dev/null
+++ b/tests/setup/automatic_installation_exclude_spec.lua
@@ -0,0 +1,44 @@
+local spy = require "luassert.spy"
+local lspconfig = require "lspconfig"
+local configs = require "lspconfig.configs"
+local servers = require "nvim-lsp-installer.servers"
+
+describe("automatic_installation_exclude", function()
+    it(
+        "should install servers set up via lspconfig",
+        async_test(function()
+            local server1_installer_spy = spy.new()
+            local server2_installer_spy = spy.new()
+            local server1 = ServerGenerator {
+                name = "automatic_installation_exclude1",
+                installer = function()
+                    server1_installer_spy()
+                end,
+            }
+            local server2 = ServerGenerator {
+                name = "automatic_installation_exclude2",
+                installer = function()
+                    server2_installer_spy()
+                end,
+            }
+
+            servers.register(server1)
+            servers.register(server2)
+
+            configs[server1.name] = { default_config = {} }
+            configs[server2.name] = { default_config = {} }
+
+            require("nvim-lsp-installer").setup {
+                automatic_installation = { exclude = { server2.name } },
+            }
+
+            lspconfig[server1.name].setup {}
+            lspconfig[server2.name].setup {}
+
+            assert.wait_for(function()
+                assert.spy(server1_installer_spy).was_called(1)
+                assert.spy(server2_installer_spy).was_called(0)
+            end)
+        end)
+    )
+end)
diff --git a/tests/setup/automatic_installation_spec.lua b/tests/setup/automatic_installation_spec.lua
new file mode 100644
index 00000000..ed35a63a
--- /dev/null
+++ b/tests/setup/automatic_installation_spec.lua
@@ -0,0 +1,43 @@
+local spy = require "luassert.spy"
+local lspconfig = require "lspconfig"
+local configs = require "lspconfig.configs"
+local servers = require "nvim-lsp-installer.servers"
+
+describe("automatic_installation", function()
+    it(
+        "should install servers set up via lspconfig",
+        async_test(function()
+            local server1_installer_spy = spy.new()
+            local server2_installer_spy = spy.new()
+            local server1 = ServerGenerator {
+                name = "automatic_installation1",
+                installer = function()
+                    server1_installer_spy()
+                end,
+            }
+            local server2 = ServerGenerator {
+                name = "automatic_installation2",
+                installer = function()
+                    server2_installer_spy()
+                end,
+            }
+
+            servers.register(server1)
+            servers.register(server2)
+
+            configs[server1.name] = { default_config = {} }
+            configs[server2.name] = { default_config = {} }
+
+            require("nvim-lsp-installer").setup {
+                automatic_installation = true,
+            }
+
+            lspconfig[server1.name].setup {}
+
+            assert.wait_for(function()
+                assert.spy(server1_installer_spy).was_called(1)
+                assert.spy(server2_installer_spy).was_called(0)
+            end)
+        end)
+    )
+end)
diff --git a/tests/setup/ensure_installed_spec.lua b/tests/setup/ensure_installed_spec.lua
new file mode 100644
index 00000000..19bb1c8e
--- /dev/null
+++ b/tests/setup/ensure_installed_spec.lua
@@ -0,0 +1,39 @@
+local spy = require "luassert.spy"
+local configs = require "lspconfig.configs"
+local servers = require "nvim-lsp-installer.servers"
+
+describe("ensure_installed", function()
+    it(
+        "should install servers",
+        async_test(function()
+            local server1_installer_spy = spy.new()
+            local server2_installer_spy = spy.new()
+            local server1 = ServerGenerator {
+                name = "ensure_installed1",
+                installer = function()
+                    server1_installer_spy()
+                end,
+            }
+            local server2 = ServerGenerator {
+                name = "ensure_installed2",
+                installer = function()
+                    server2_installer_spy()
+                end,
+            }
+
+            servers.register(server1)
+            servers.register(server2)
+
+            configs[server1.name] = { default_config = {} }
+            configs[server2.name] = { default_config = {} }
+
+            require("nvim-lsp-installer").setup {
+                ensure_installed = { server1.name, server2.name },
+            }
+            assert.wait_for(function()
+                assert.spy(server1_installer_spy).was_called(1)
+                assert.spy(server2_installer_spy).was_called(1)
+            end)
+        end)
+    )
+end)