Add ActionView::TestCase DSL generator

lib/tapioca/compilers/dsl/action_view_test_helpers.rb

@@ -0,0 +1,108 @@
+# typed: strict
+# frozen_string_literal: true
+
+begin
+  require "action_view/test_case"
+rescue LoadError
+  return
+end
+
+module Tapioca
+  module Compilers
+    module Dsl
+      # `Tapioca::Compilers::Dsl::ActionViewTestHelpers` decorates RBI files for all
+      # subclasses of `ActionView::TestCase` with the helpers that are included dynamically.
+      #
+      # For example, considering the `UsersHelper` module:
+      #
+      # ~~~rb
+      # module UsersHelper
+      #   def current_user_name
+      #     # ...
+      #   end
+      # end
+      # ~~~
+      #
+      # and its respective test:
+      #
+      # ~~~rb
+      # class UsersHelperTest < ActionView::TestCase
+      #   test "current_user_name works" do
+      #     assert_equal("John", current_user_name)
+      #   end
+      # end
+      # ~~~
+      #
+      # this generator will produce an RBI file `users_helper_test.rbi` with the following content:
+      #
+      # ~~~rbi
+      # # users_helper_test.rbi
+      # # typed: strong
+      # class UsersHelperTest
+      #   include HelperMethods
+      #
+      #   module HelperMethods
+      #     include ::UsersHelper
+      #   end
+      # end
+      # ~~~
+      class ActionViewTestHelpers < Base
+        extend T::Sig
+
+        sig do
+          override
+            .params(root: RBI::Tree, constant: T.class_of(ActionView::TestCase))
+            .void
+        end
+        def decorate(root, constant)
+          # The helpers are dynamically included in the helpers module when `include_helper_modules!` is called.
+          constant.send(:include_helper_modules!)
+          helpers_module = constant._helpers
+
+          helper_methods_name = "HelperMethods"
+
+          root.create_path(constant) do |klass|
+            klass.create_module(helper_methods_name) do |helper_methods|
+              # Find all the included helper modules and generate an include
+              # for each of those helper modules
+              gather_includes(helpers_module).each do |helper_module_name|
+                helper_methods.create_include(helper_module_name)
+              end
+
+              # Generate a method definition in the helper module for each
+              # helper method defined via the `helper_method` call in the test case.
+              helpers_module.instance_methods(false).each do |method_name|
+                helper_methods.create_method(
+                  method_name.to_s,
+                  parameters: [
+                    create_rest_param("args", type: "T.untyped"),
+                    create_kw_rest_param("kwargs", type: "T.untyped"),
+                    create_block_param("blk", type: "T.untyped"),
+                  ],
+                  return_type: "T.untyped"
+                )
+              end
+            end
+
+            klass.create_include(helper_methods_name)
+          end
+        end
+
+        sig { override.returns(T::Enumerable[Module]) }
+        def gather_constants
+          descendants_of(ActionView::TestCase)
+        end
+
+        private
+
+        sig { params(mod: Module).returns(T::Array[String]) }
+        def gather_includes(mod)
+          mod.ancestors
+            .reject { |ancestor| ancestor.is_a?(Class) || ancestor == mod || name_of(ancestor).nil? }
+            .map { |ancestor| T.must(qualified_name_of(ancestor)) }
+            .reverse
+        end
+      end
+    end
+  end
+end

manual/generator_actionviewtesthelpers.md

@@ -0,0 +1,38 @@
+## ActionViewTestHelpers
+
+`Tapioca::Compilers::Dsl::ActionViewTestHelpers` decorates RBI files for all
+subclasses of `ActionView::TestCase` with the helpers that are included dynamically.
+
+For example, considering the `UsersHelper` module:
+
+~~~rb
+module UsersHelper
+  def current_user_name
+    # ...
+  end
+end
+~~~
+
+and its respective test:
+
+~~~rb
+class UsersHelperTest < ActionView::TestCase
+  test "current_user_name works" do
+    assert_equal("John", current_user_name)
+  end
+end
+~~~
+
+this generator will produce an RBI file `users_helper_test.rbi` with the following content:
+
+~~~rbi
+# users_helper_test.rbi
+# typed: strong
+class UsersHelperTest
+  include HelperMethods
+
+  module HelperMethods
+    include ::UsersHelper
+  end
+end
+~~~

manual/generators.md

@@ -6,6 +6,7 @@ In the following section you will find all available DSL generators:
 * [AASM](generator_aasm.md)
 * [ActionControllerHelpers](generator_actioncontrollerhelpers.md)
 * [ActionMailer](generator_actionmailer.md)
+* [ActionViewTestHelpers](generator_actionviewtesthelpers.md)
 * [ActiveJob](generator_activejob.md)
 * [ActiveModelAttributes](generator_activemodelattributes.md)
 * [ActiveModelSecurePassword](generator_activemodelsecurepassword.md)

spec/tapioca/compilers/dsl/action_view_test_helpers_spec.rb

@@ -0,0 +1,101 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "spec_helper"
+
+class Tapioca::Compilers::Dsl::ActionViewTestHelpersSpec < DslSpec
+  describe("#initialize") do
+    after(:each) do
+      T.unsafe(self).assert_no_generated_errors
+    end
+
+    it("doesn't gather anything if there are no ActionView::TestCase tests") do
+      assert_empty(gathered_constants)
+    end
+
+    it("gathers ActionView::TestCase tests") do
+      add_ruby_file("users_helper_test.rb", <<~RUBY)
+        class UsersHelperTest < ActionView::TestCase
+        end
+      RUBY
+
+      assert_equal(["UsersHelperTest"], gathered_constants)
+    end
+  end
+
+  describe("#decorate") do
+    after(:each) do
+      T.unsafe(self).assert_no_generated_errors
+    end
+
+    it("generates a module with all dynamic helper inclusions") do
+      add_ruby_file("users_helper.rb", <<~RUBY)
+        module UsersHelper
+          def current_user_name
+            "John"
+          end
+        end
+
+        module SomeOtherHelperModule
+        end
+      RUBY
+
+      add_ruby_file("users_helper_test.rb", <<~RUBY)
+        class UsersHelperTest < ActionView::TestCase
+          helper SomeOtherHelperModule
+          helper_method :foo
+        end
+      RUBY
+
+      expected = <<~RBI
+        # typed: strong
+
+        class UsersHelperTest
+          include HelperMethods
+
+          module HelperMethods
+            include ::ActionView::TestCase::HelperMethods
+            include ::SomeOtherHelperModule
+            include ::UsersHelper
+
+            sig { params(args: T.untyped, kwargs: T.untyped, blk: T.untyped).returns(T.untyped) }
+            def foo(*args, **kwargs, &blk); end
+          end
+        end
+      RBI
+
+      assert_equal(expected, rbi_for(:UsersHelperTest))
+    end
+
+    it("generates a module with a custom helper module under test definition") do
+      add_ruby_file("users_helper.rb", <<~RUBY)
+        module SomeOtherHelperModule
+          def current_user_name
+            "John"
+          end
+        end
+      RUBY
+
+      add_ruby_file("users_helper_test.rb", <<~RUBY)
+        class UsersHelperTest < ActionView::TestCase
+          tests SomeOtherHelperModule
+        end
+      RUBY
+
+      expected = <<~RBI
+        # typed: strong
+
+        class UsersHelperTest
+          include HelperMethods
+
+          module HelperMethods
+            include ::ActionView::TestCase::HelperMethods
+            include ::SomeOtherHelperModule
+          end
+        end
+      RBI
+
+      assert_equal(expected, rbi_for(:UsersHelperTest))
+    end
+  end
+end