refactor!: refactor installer internals and add new Package class methods (#1523)

This contains the following changes:
1) `Package:install()` now accepts a second, optional, callback argument which is called when installation finishes
   (successfully or not).
2) Adds a `Package:is_installing()` method.

This contains the following breaking changes:
1) `Package:install()` will now error when called while an installation is already ongoing. Use the new
   `Package:is_installing()` method to check whether an installation is already running.

This also refactors large portions of the tests by removing test globals, removing async_test, and adding the
`mason-test` Lua module instead. Test helpers via globals are problematic to work with due to not being detected through
tools like the Lua language server without additional configuration. This has been replaced with a Lua module
`mason-test`. `async_test` has also been removed in favour of explicitly making use of the `mason-core.async` API. These
changes stands for a significant portion of the diff.

1 files changed, 83 insertions, 0 deletions

diff --git a/lua/mason-core/installer/compiler/util.lua b/lua/mason-core/installer/compiler/util.lua
new file mode 100644
index 00000000..b3735c9c
--- /dev/null
+++ b/lua/mason-core/installer/compiler/util.lua
@@ -0,0 +1,83 @@
+local Optional = require "mason-core.optional"
+local Result = require "mason-core.result"
+local _ = require "mason-core.functional"
+local installer = require "mason-core.installer"
+local log = require "mason-core.log"
+local platform = require "mason-core.platform"
+
+local M = {}
+
+---@generic T : { target: Platform | Platform[] }
+---@param candidates T[] | T
+---@param opts PackageInstallOpts
+---@return Result # Result<T>
+function M.coalesce_by_target(candidates, opts)
+    if not _.is_list(candidates) then
+        return Result.success(candidates)
+    end
+    return Optional.of_nilable(_.find_first(function(asset)
+        if opts.target then
+            -- Matching against a provided target rather than the current platform is an escape hatch primarily meant
+            -- for automated testing purposes.
+            if type(asset.target) == "table" then
+                return _.any(_.equals(opts.target), asset.target)
+            else
+                return asset.target == opts.target
+            end
+        else
+            if type(asset.target) == "table" then
+                return _.any(function(target)
+                    return platform.is[target]
+                end, asset.target)
+            else
+                return platform.is[asset.target]
+            end
+        end
+    end, candidates)):ok_or "PLATFORM_UNSUPPORTED"
+end
+
+---Checks whether a custom version of a package installation corresponds to a valid version.
+---@async
+---@param versions_thunk async fun(): Result Result<string[]>
+function M.ensure_valid_version(versions_thunk)
+    local ctx = installer.context()
+    local version = ctx.opts.version
+
+    if version and not ctx.opts.force then
+        ctx.stdio_sink.stdout "Fetching available versions…\n"
+        local all_versions = versions_thunk()
+        if all_versions:is_failure() then
+            log.warn("Failed to fetch versions for package", ctx.package)
+            -- Gracefully fail (i.e. optimistically continue package installation)
+            return Result.success()
+        end
+        all_versions = all_versions:get_or_else {}
+
+        if not _.any(_.equals(version), all_versions) then
+            ctx.stdio_sink.stderr(("Tried to install invalid version %q. Available versions:\n"):format(version))
+            ctx.stdio_sink.stderr(_.compose(_.join "\n", _.map(_.join ", "), _.split_every(15))(all_versions))
+            ctx.stdio_sink.stderr "\n\n"
+            ctx.stdio_sink.stderr(
+                ("Run with --force flag to bypass version validation:\n  :MasonInstall --force %s@%s\n\n"):format(
+                    ctx.package.name,
+                    version
+                )
+            )
+            return Result.failure(("Version %q is not available."):format(version))
+        end
+    end
+
+    return Result.success()
+end
+
+---@param platforms string[]
+function M.ensure_valid_platform(platforms)
+    if not _.any(function(target)
+        return platform.is[target]
+    end, platforms) then
+        return Result.failure "PLATFORM_UNSUPPORTED"
+    end
+    return Result.success()
+end
+
+return M