test: Suppress experimental feature warnings in unit tests

Unit tests instantiate many @experimental-decorated classes, flooding
test output with [EXPERIMENTAL] UserWarning messages. Set
ADK_SUPPRESS_EXPERIMENTAL_FEATURE_WARNINGS=true in the unittests
conftest to silence them session-wide.

The four *_no_parens / *_empty_parens decorator tests that assert the
warning fires now delenv the suppress var first, matching the pattern
already used by their sibling tests, so they remain valid under the new
default.

Change-Id: I589079da589eba76f799413e19287fd264986dd6

Author: Jacksunwei

tests/unittests/conftest.py

@@ -28,6 +28,7 @@
     'GOOGLE_CLOUD_PROJECT': 'fake_google_cloud_project',
     'GOOGLE_CLOUD_LOCATION': 'fake_google_cloud_location',
     'ADK_ALLOW_WIP_FEATURES': 'true',
+    'ADK_SUPPRESS_EXPERIMENTAL_FEATURE_WARNINGS': 'true',
 }
 
 ENV_SETUPS = {

tests/unittests/utils/test_feature_decorator.py

@@ -306,8 +306,11 @@ def test_experimental_class_not_bypassed_for_false_env_var(monkeypatch):
       assert "[EXPERIMENTAL] ExperimentalClass:" in str(w[0].message)
 
 
-def test_experimental_class_no_parens_warns():
+def test_experimental_class_no_parens_warns(monkeypatch):
   """Test that experimental class without parentheses shows default warning."""
+  monkeypatch.delenv(
+      "ADK_SUPPRESS_EXPERIMENTAL_FEATURE_WARNINGS", raising=False
+  )
   with warnings.catch_warnings(record=True) as w:
     warnings.simplefilter("always")
 
@@ -323,8 +326,11 @@ def test_experimental_class_no_parens_warns():
     )
 
 
-def test_experimental_class_empty_parens_warns():
+def test_experimental_class_empty_parens_warns(monkeypatch):
   """Test that experimental class with empty parentheses shows default warning."""
+  monkeypatch.delenv(
+      "ADK_SUPPRESS_EXPERIMENTAL_FEATURE_WARNINGS", raising=False
+  )
   with warnings.catch_warnings(record=True) as w:
     warnings.simplefilter("always")
 
@@ -340,8 +346,11 @@ def test_experimental_class_empty_parens_warns():
     )
 
 
-def test_experimental_function_no_parens_warns():
+def test_experimental_function_no_parens_warns(monkeypatch):
   """Test that experimental function without parentheses shows default warning."""
+  monkeypatch.delenv(
+      "ADK_SUPPRESS_EXPERIMENTAL_FEATURE_WARNINGS", raising=False
+  )
   with warnings.catch_warnings(record=True) as w:
     warnings.simplefilter("always")
 
@@ -356,8 +365,11 @@ def test_experimental_function_no_parens_warns():
     )
 
 
-def test_experimental_function_empty_parens_warns():
+def test_experimental_function_empty_parens_warns(monkeypatch):
   """Test that experimental function with empty parentheses shows default warning."""
+  monkeypatch.delenv(
+      "ADK_SUPPRESS_EXPERIMENTAL_FEATURE_WARNINGS", raising=False
+  )
   with warnings.catch_warnings(record=True) as w:
     warnings.simplefilter("always")