Fix ALUMNI_STDLIBS key for observable

lib/rbs/collection/config/lockfile_generator.rb

@@ -6,6 +6,7 @@ class Config
       class LockfileGenerator
         # Stdlibs that used to be bundled in rbs-gem but are now maintained in their own gems.
         #
+        # The key is the library name under `stdlib/` (not necessarily the gem name, see `ALUMNI_GEM_NAMES`).
         # The value is the version requirement of the gem that ships the type definitions in its `sig/` directory,
         # or `nil` if no released version of the gem ships them yet.
         ALUMNI_STDLIBS = {
@@ -20,11 +21,16 @@ class LockfileGenerator
           "minitest" => nil,
           "net-smtp" => nil,
           "nkf" => ">= 0.3.0",
-          "observer" => nil,
+          "observable" => nil,
           "cgi" => nil,
           "pstore" => nil,
         }
 
+        # Stdlibs in `ALUMNI_STDLIBS` whose gem name differs from the library name.
+        ALUMNI_GEM_NAMES = {
+          "observable" => "observer",
+        }
+
         NONGEM_STDLIBS = Set[
           "cgi-escape",
           "coverage",
@@ -217,12 +223,13 @@ def generate
             return
           when *ALUMNI_STDLIBS.keys
             version = ALUMNI_STDLIBS.fetch(name)
+            gem_name = ALUMNI_GEM_NAMES.fetch(name, name)
             if from_gem
               # From `dependencies:` of a `manifest.yaml` of a gem
               source = find_source(name: name) or raise
               if source.is_a?(Sources::Stdlib) && version
                 RBS.logger.warn {
-                  "`#{name}` is included in the RBS dependencies of `#{from_gem}`, but the type definition as a stdlib in rbs-gem is deprecated. Add `#{name}` (#{version}) to the dependency of your Ruby program to use the gem-bundled type definition."
+                  "`#{name}` is included in the RBS dependencies of `#{from_gem}`, but the type definition as a stdlib in rbs-gem is deprecated. Add `#{gem_name}` (#{version}) to the dependency of your Ruby program to use the gem-bundled type definition."
                 }
               else
                 RBS.logger.info {
@@ -235,7 +242,7 @@ def generate
               # From `gems:` of a `rbs_collection.yaml`
               RBS.logger.warn {
                 if version
-                  "`#{name}` as a stdlib in rbs-gem is deprecated. Add `#{name}` (#{version}) to the dependency of your Ruby program to use the gem-bundled type definition."
+                  "`#{name}` as a stdlib in rbs-gem is deprecated. Add `#{gem_name}` (#{version}) to the dependency of your Ruby program to use the gem-bundled type definition."
                 else
                   "`#{name}` as a stdlib in rbs-gem is deprecated. Delete `#{name}` from the RBS dependencies in your rbs_collection.yaml."
                 end

sig/collection/config/lockfile_generator.rbs

@@ -8,6 +8,10 @@ module RBS
         #
         ALUMNI_STDLIBS: Hash[String, String?]
 
+        # Stdlibs in `ALUMNI_STDLIBS` whose gem name differs from the library name.
+        #
+        ALUMNI_GEM_NAMES: Hash[String, String]
+
         NONGEM_STDLIBS: Set[String]
 
         class GemfileLockMismatchError < StandardError

test/rbs/collection/config_test.rb

@@ -415,6 +415,47 @@ def test_generate_lock_from_rubygems
        2.2.0
   GEMFILE_LOCK
 
+  def test_generate_lock_from_alumni_stdlib__observable
+    # The stdlib is named `observable` while the gem is named `observer`.
+    # The deprecation warning must be keyed by the stdlib name, or it never fires.
+    mktmpdir do |tmpdir|
+      config_path = tmpdir / 'rbs_collection.yaml'
+      config_path.write <<~YAML
+        sources:
+          - name: ruby/gem_rbs_collection
+            remote: https://github.com/ruby/gem_rbs_collection.git
+            revision: cde6057e7546843ace6420c5783dd945c6ccda54
+            repo_dir: gems
+
+        path: /path/to/somewhere
+
+        gems:
+          - name: observable
+      YAML
+      gemfile_path = tmpdir / 'Gemfile'
+      gemfile_path.write 'source "https://rubygems.org"'
+      gemfile_lock_path = tmpdir / 'Gemfile.lock'
+      gemfile_lock_path.write EMPTY_GEMFILE_LOCK
+
+      definition = Bundler::Definition.build(gemfile_path, gemfile_lock_path, false)
+      lockfile, log = with_logger_output(level: Logger::WARN) do
+        _config, lockfile = RBS::Collection::Config.generate_lockfile(config_path: config_path, definition: definition)
+        lockfile
+      end
+
+      assert_config <<~YAML, YAML.dump(lockfile.to_lockfile)
+        path: "/path/to/somewhere"
+        gemfile_lock_path: 'Gemfile.lock'
+        gems:
+          - name: observable
+            version: "0"
+            source:
+              type: stdlib
+      YAML
+      assert_include log, '`observable` as a stdlib in rbs-gem is deprecated.'
+    end
+  end
+
   def test_generate_lock_from_alumni_stdlib__kconv
     # `kconv` is never released as a gem; its types are shipped with the `nkf` gem.
     mktmpdir do |tmpdir|