Address review: correct the source of the include, keep it for unmapped fixtures

Two fixes from review.

The include does not come from a railtie initializer — there is none. It comes
from the `:active_support_test_case` load hook in `rails/test_help.rb`, which an
app requires from `test_helper.rb`, so it never runs during RBI generation.
Reword the comment and the manual accordingly.

The early return sat below the `select!` that drops fixture sets whose model
constant cannot be resolved, so an app with fixture files but no matching models
wrote `fixtures :all` and still got no include. Move the return above the
`select!`: apps with no fixture files at all keep generating nothing, everything
else gets the include.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: 2 people

lib/tapioca/dsl/compilers/active_record_fixtures.rb

@@ -37,9 +37,10 @@ module Compilers
       # ~~~
       #
       # The `include` is generated because Rails mixes `ActiveRecord::TestFixtures` into
-      # `ActiveSupport::TestCase` from the `active_record.test_fixtures` railtie initializer, which
-      # does not run during gem RBI generation. Without it, Sorbet does not see the class methods
-      # the module contributes via `mixes_in_class_methods`, such as `fixtures`.
+      # `ActiveSupport::TestCase` from a `:active_support_test_case` load hook in `rails/test_help.rb`,
+      # which is only required from an app's `test_helper.rb` and therefore never runs during RBI
+      # generation. Without it, Sorbet does not see the class methods the module contributes via
+      # `mixes_in_class_methods`, such as `fixtures`.
       #: [ConstantType = singleton(ActiveSupport::TestCase)]
       class ActiveRecordFixtures < Compiler
         MISSING = Object.new
@@ -53,9 +54,10 @@ def decorate
             method_names_from_eager_fixture_loader
           end
 
-          method_names.select! { |name| fixture_class_mapping_from_fixture_files[name] != MISSING }
           return if method_names.empty?
 
+          method_names.select! { |name| fixture_class_mapping_from_fixture_files[name] != MISSING }
+
           root.create_path(constant) do |mod|
             mod.create_include("ActiveRecord::TestFixtures")
 

manual/compiler_activerecordfixtures.md

@@ -29,6 +29,7 @@ end
 ~~~
 
 The `include` is generated because Rails mixes `ActiveRecord::TestFixtures` into
-`ActiveSupport::TestCase` from the `active_record.test_fixtures` railtie initializer, which
-does not run during gem RBI generation. Without it, Sorbet does not see the class methods
-the module contributes via `mixes_in_class_methods`, such as `fixtures`.
+`ActiveSupport::TestCase` from a `:active_support_test_case` load hook in `rails/test_help.rb`,
+which is only required from an app's `test_helper.rb` and therefore never runs during RBI
+generation. Without it, Sorbet does not see the class methods the module contributes via
+`mixes_in_class_methods`, such as `fixtures`.

spec/tapioca/dsl/compilers/active_record_fixtures_spec.rb

@@ -91,6 +91,24 @@ def posts(fixture_name = nil, *other_fixtures); end
               assert_equal(expected, rbi_for("ActiveSupport::TestCase"))
             end
 
+            it "generates only the include if no fixture has an associated model" do
+              add_content_file("test/fixtures/serialized_data.yml", <<~YAML)
+                ---
+                field1: 123
+                name: Hello
+              YAML
+
+              expected = <<~RBI
+                # typed: strong
+
+                class ActiveSupport::TestCase
+                  include ActiveRecord::TestFixtures
+                end
+              RBI
+
+              assert_equal(expected, rbi_for("ActiveSupport::TestCase"))
+            end
+
             it "generates methods for fixtures" do
               add_content_file("test/fixtures/posts.yml", <<~YAML)
                 super_post: