fix: Fix tap tests for multiple test classes with different input cat…

…alogs (#1913)

* fix: Fix tap tests for multiple test classes with different input catalogs

* Fix mro mess

* Test the test class mro

singer_sdk/testing/factory.py

@@ -21,8 +21,20 @@
 class BaseTestClass:
     """Base test class."""
 
-    params: t.ClassVar[dict] = {}
-    param_ids: t.ClassVar[dict] = {}
+    params: dict[str, t.Any]
+    param_ids: dict[str, list[str]]
+
+    def __init_subclass__(cls, **kwargs: t.Any) -> None:
+        """Initialize a subclass.
+
+        Args:
+            **kwargs: Keyword arguments.
+        """
+        # Add empty params and param_ids attributes to a direct subclass but not to
+        # subclasses of subclasses
+        if cls.__base__ == BaseTestClass:
+            cls.params = {}
+            cls.param_ids = {}
 
 
 class TapTestClassFactory:
@@ -183,7 +195,7 @@ def _annotate_test_class(  # noqa: C901
                         test = test_class()
                         test_name = f"test_{suite.kind}_{test.name}"
                         test_params = []
-                        test_ids = []
+                        test_ids: list[str] = []
                         for stream in streams:
                             test_params.extend(
                                 [

tests/core/test_testing.py

@@ -4,6 +4,8 @@
 
 import pytest
 
+from singer_sdk.testing.factory import BaseTestClass
+
 
 def test_module_deprecations():
     with pytest.deprecated_call():
@@ -19,3 +21,23 @@ def test_module_deprecations():
         match="module singer_sdk.testing has no attribute",
     ):
         testing.foo  # noqa: B018
+
+
+def test_test_class_mro():
+    class PluginTestClass(BaseTestClass):
+        pass
+
+    PluginTestClass.params["x"] = 1
+
+    class AnotherPluginTestClass(BaseTestClass):
+        pass
+
+    AnotherPluginTestClass.params["x"] = 2
+    AnotherPluginTestClass.params["y"] = 3
+
+    class SubPluginTestClass(PluginTestClass):
+        pass
+
+    assert PluginTestClass.params == {"x": 1}
+    assert AnotherPluginTestClass.params == {"x": 2, "y": 3}
+    assert SubPluginTestClass.params == {"x": 1}