diff --git a/tests/test_classes.py b/tests/test_classes.py
index a23e89f10..37097a452 100644
--- a/tests/test_classes.py
+++ b/tests/test_classes.py
@@ -6,7 +6,7 @@
 def _file_change(filename: str) -> FileChange:
     return FileChange(
         pr_number=0,
-        repository_full_name='nextcloud/android',
+        repository_full_name='example/repo',
         filename=filename,
         changes=10,
         additions=10,
@@ -35,30 +35,66 @@ def test_is_test_file_detects_gradle_test_source_sets(filename):
 @pytest.mark.parametrize(
     'filename',
     [
+        # Real files in mastodon/mastodon spec/ tree (verified via Contents API).
         'spec/models/account_spec.rb',
+        'spec/models/account_alias_spec.rb',
+        'spec/models/account_conversation_spec.rb',
         'spec/services/account_search_service_spec.rb',
-        'spec/rails_helper.rb',
-        'spec/support/factory_bot.rb',
-        'engines/users/spec/models/user_spec.rb',
+        'spec/services/after_block_service_spec.rb',
+        'spec/controllers/application_controller_spec.rb',
+        'spec/controllers/follower_accounts_controller_spec.rb',
+        # *_spec.rb outside spec/ — filename pattern alone must catch.
         'lib/foo_spec.rb',
         'app/models/user_spec.rb',
+        # Other RSpec-style ecosystems using underscore-spec naming.
         'src/util_spec.js',
+        'pkg/handler_spec.ts',
+    ],
+)
+def test_is_test_file_detects_rspec_underscore_spec_suffix(filename):
+    assert _file_change(filename).is_test_file() is True
+
+
+@pytest.mark.parametrize(
+    'filename',
+    [
+        # RSpec helper/support files that don't end in _spec.rb but live in spec/.
+        'spec/rails_helper.rb',
+        'spec/support/factory_bot.rb',
+        'spec/support/database_cleaner.rb',
+        'spec/support/shared_examples.rb',
+        # Nested spec/ at non-root.
+        'engines/users/spec/models/user_spec.rb',
+        'engines/users/spec/factories.rb',
     ],
 )
-def test_is_test_file_detects_rspec_conventions(filename):
+def test_is_test_file_detects_spec_directory(filename):
     assert _file_change(filename).is_test_file() is True
 
 
 @pytest.mark.parametrize(
     'filename',
     [
+        # Lookalikes that must NOT trip the new patterns.
+        # Filename "spec" prefix without trailing underscore-dot.
         'app/build.gradle.kts',
         'src/main/java/com/example/Bar.java',
         'docs/androidtest.md',
         'tools/androidtestutils.py',
         'app/models/specification.rb',
+        'src/spectrum.rb',
         'lib/spectrum.rb',
+        'app/models/respec.rb',
+        'lib/aspec.rb',
+        'lib/inspector.rb',
+        'src/spec.rb',
+        'src/spec.js',
         'config/spec.rb',
+        # Pre-existing patterns must continue to reject ordinary source.
+        'app/models/account.rb',
+        'lib/foo.rb',
+        'src/main.py',
+        'src/foo/bar.py',
     ],
 )
 def test_is_test_file_rejects_non_test_lookalikes(filename):
@@ -66,10 +102,14 @@ def test_is_test_file_rejects_non_test_lookalikes(filename):
 
 
 def test_is_test_file_preserves_existing_test_conventions():
+    assert _file_change('tests/test_foo.py').is_test_file() is True
     assert _file_change('src/tests/test_foo.py').is_test_file() is True
     assert _file_change('src/__tests__/foo.test.js').is_test_file() is True
     assert _file_change('pkg/foo_test.go').is_test_file() is True
-    assert _file_change('src/foo/bar.py').is_test_file() is False
+    assert _file_change('app/foo_tests.rb').is_test_file() is True
+    assert _file_change('src/foo.spec.js').is_test_file() is True
+    assert _file_change('app/spec_helper.rb').is_test_file() is True
+    assert _file_change('app/test_helper.py').is_test_file() is True
 
 
 def test_pull_request_handles_deleted_label_event():