Remove unused testresources import and related load_tests function from unittestadapter (#25928)

goal to resolve CI issues

Keeps coverage of the testscenarios-based dynamic test-ID pattern (which
was the whole point of this fixture). Declaring testtools explicitly
replaces the fragile transitive dependency that was causing the CI
import failure described in test-scenarios-ci-failure.md.

---------

Co-authored-by: Copilot <copilot@github.com>

Author: eleanorjboyd

build/test-requirements.txt

@@ -12,8 +12,8 @@ flask
 fastapi
 uvicorn
 django
-testresources
 testscenarios
+testtools
 
 # Integrated TensorBoard tests
 tensorboard

python_files/tests/unittestadapter/.data/test_scenarios/tests/__init__.py

@@ -1,15 +1,2 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License.
-
-import os
-
-import testresources
-from testscenarios import generate_scenarios
-
-def load_tests(loader, tests, pattern):
-    this_dir = os.path.dirname(__file__)
-    mytests = loader.discover(start_dir=this_dir, pattern=pattern)
-    result = testresources.OptimisingTestSuite()
-    result.addTests(generate_scenarios(mytests))
-    result.addTests(generate_scenarios(tests))
-    return result

python_files/tests/unittestadapter/.data/test_scenarios/tests/test_scene.py

@@ -1,13 +1,27 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License.
 
-from testscenarios import TestWithScenarios
+import unittest
+
+from testscenarios import TestWithScenarios, generate_scenarios
+
+
+def load_tests(loader, standard_tests, pattern):  # noqa: ARG001
+    # Pre-expand ``TestWithScenarios`` scenarios at load time so individual
+    # scenario-multiplied test IDs (e.g. ``test_operations(add)``) can be
+    # resolved by ``unittest.TestLoader.loadTestsFromName``. Without this,
+    # ``TestWithScenarios`` only multiplies scenarios at ``run()`` time and
+    # loading a specific scenario by name raises ``AttributeError``.
+    result = unittest.TestSuite()
+    result.addTests(generate_scenarios(standard_tests))
+    return result
+
 
 class TestMathOperations(TestWithScenarios):
     scenarios = [
         ('add', {'test_id': 'test_add', 'a': 5, 'b': 3, 'expected': 8}),
         ('subtract', {'test_id': 'test_subtract', 'a': 5, 'b': 3, 'expected': 2}),
-        ('multiply', {'test_id': 'test_multiply', 'a': 5, 'b': 3, 'expected': 15})
+        ('multiply', {'test_id': 'test_multiply', 'a': 5, 'b': 3, 'expected': 15}),
     ]
     a: int = 0
     b: int = 0