Generator for ActiveJob::Base descendants

Need this to properly type `perform_later` and `perform_now` methods, as their arguments change based on the signature of the `perform` method.

lib/tapioca/compilers/dsl/active_job.rb

@@ -0,0 +1,71 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "parlour"
+
+begin
+  require "active_job"
+rescue LoadError
+  return
+end
+
+module Tapioca
+  module Compilers
+    module Dsl
+      # `Tapioca::Compilers::Dsl::ActiveJob` generates RBI files for subclasses of
+      # [`ActiveJob::Base`](https://api.rubyonrails.org/classes/ActiveJob/Base.html).
+      #
+      # For example, with the following `ActiveJob` subclass:
+      #
+      # ~~~rb
+      # class NotifyUserJob < ActiveJob::Base
+      #   def perform(user)
+      #     # ...
+      #   end
+      # end
+      # ~~~
+      #
+      # this generator will produce the RBI file `notify_user_job.rbi` with the following content:
+      #
+      # ~~~rbi
+      # # notify_user_job.rbi
+      # # typed: true
+      # class NotifyUserJob
+      #   sig { params(user: T.untyped).returns(T.attached_class) }
+      #   def self.perform_later(user); end
+      #
+      #   sig { params(user: T.untyped).returns(T.attached_class) }
+      #   def self.perform_now(user); end
+      # end
+      # ~~~
+      class ActiveJob < Base
+        extend T::Sig
+
+        sig { override.params(root: Parlour::RbiGenerator::Namespace, constant: T.class_of(::ActiveJob::Base)).void }
+        def decorate(root, constant)
+          root.path(constant) do |job|
+            next unless constant.instance_methods(false).include?(:perform)
+
+            method = constant.instance_method(:perform)
+            parameters = compile_method_parameters_to_parlour(method)
+
+            %w[perform_later perform_now].each do |name|
+              create_method(
+                job,
+                name,
+                parameters: parameters,
+                return_type: "T.attached_class",
+                class_method: true
+              )
+            end
+          end
+        end
+
+        sig { override.returns(T::Enumerable[Module]) }
+        def gather_constants
+          ::ActiveJob::Base.descendants
+        end
+      end
+    end
+  end
+end

manual/generator_activejob.md

@@ -0,0 +1,28 @@
+## ActiveJob
+
+`Tapioca::Compilers::Dsl::ActiveJob` generates RBI files for subclasses of
+[`ActiveJob::Base`](https://api.rubyonrails.org/classes/ActiveJob/Base.html).
+
+For example, with the following `ActiveJob` subclass:
+
+~~~rb
+class NotifyUserJob < ActiveJob::Base
+  def perform(user)
+    # ...
+  end
+end
+~~~
+
+this generator will produce the RBI file `notify_user_job.rbi` with the following content:
+
+~~~rbi
+# notify_user_job.rbi
+# typed: true
+class NotifyUserJob
+  sig { params(user: T.untyped).returns(T.attached_class) }
+  def self.perform_later(user); end
+
+  sig { params(user: T.untyped).returns(T.attached_class) }
+  def self.perform_now(user); end
+end
+~~~

manual/generators.md

@@ -5,6 +5,7 @@ In the following section you will find all available DSL generators:
 <!-- START_GENERATOR_LIST -->
 * [ActionControllerHelpers](generator_actioncontrollerhelpers.md)
 * [ActionMailer](generator_actionmailer.md)
+* [ActiveJob](generator_activejob.md)
 * [ActiveRecordAssociations](generator_activerecordassociations.md)
 * [ActiveRecordColumns](generator_activerecordcolumns.md)
 * [ActiveRecordEnum](generator_activerecordenum.md)

spec/tapioca/compilers/dsl/active_job_spec.rb

@@ -0,0 +1,101 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "spec_helper"
+
+class Tapioca::Compilers::Dsl::ActiveJobSpec < DslSpec
+  describe("#initialize") do
+    it("gathers no constants if there are no ActiveJob subclasses") do
+      assert_empty(gathered_constants)
+    end
+
+    it("gathers only ActiveJob subclasses") do
+      add_ruby_file("content.rb", <<~RUBY)
+        class NotifyJob < ActiveJob::Base
+        end
+
+        class User
+        end
+      RUBY
+
+      assert_equal(["NotifyJob"], gathered_constants)
+    end
+
+    it("gathers subclasses of ActiveJob subclasses") do
+      add_ruby_file("content.rb", <<~RUBY)
+        class NotifyJob < ActiveJob::Base
+        end
+
+        class SecondaryNotifyJob < NotifyJob
+        end
+      RUBY
+
+      assert_equal(["NotifyJob", "SecondaryNotifyJob"], gathered_constants)
+    end
+  end
+
+  describe("#decorate") do
+    it("generates empty RBI file if there is no perform method") do
+      add_ruby_file("job.rb", <<~RUBY)
+        class NotifyJob < ActiveJob::Base
+        end
+      RUBY
+
+      expected = <<~RBI
+        # typed: strong
+        class NotifyJob
+        end
+      RBI
+
+      assert_equal(expected, rbi_for(:NotifyJob))
+    end
+
+    it("generates correct RBI file for subclass with methods") do
+      add_ruby_file("job.rb", <<~RUBY)
+        class NotifyJob < ActiveJob::Base
+          def perform(user_id)
+            # ...
+          end
+        end
+      RUBY
+
+      expected = <<~RBI
+        # typed: strong
+        class NotifyJob
+          sig { params(user_id: T.untyped).returns(T.attached_class) }
+          def self.perform_later(user_id); end
+
+          sig { params(user_id: T.untyped).returns(T.attached_class) }
+          def self.perform_now(user_id); end
+        end
+      RBI
+
+      assert_equal(expected, rbi_for(:NotifyJob))
+    end
+
+    it("generates correct RBI file for subclass with method signatures") do
+      add_ruby_file("job.rb", <<~RUBY)
+        class NotifyJob < ActiveJob::Base
+          extend T::Sig
+          sig { params(user_id: Integer).void }
+          def perform(user_id)
+            # ...
+          end
+        end
+      RUBY
+
+      expected = <<~RBI
+        # typed: strong
+        class NotifyJob
+          sig { params(user_id: Integer).returns(T.attached_class) }
+          def self.perform_later(user_id); end
+
+          sig { params(user_id: Integer).returns(T.attached_class) }
+          def self.perform_now(user_id); end
+        end
+      RBI
+
+      assert_equal(expected, rbi_for(:NotifyJob))
+    end
+  end
+end