test: add a load smoke test for contributing samples

Add test_sample_loads, which loads and constructs the root agent of
every sample under contributing/samples the way `adk run` does. Samples
needing external infra, credentials, or optional dependencies are
skipped with a reason; three samples already broken against the current
API are marked xfail.

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 944102624

Author: GWeale

tests/unittests/test_samples.py

@@ -15,14 +15,35 @@
 from __future__ import annotations
 
 import json
+import os
 from pathlib import Path
+import sys
 
+from google.adk.agents import config_agent_utils
 from google.adk.apps.app import App
 from google.adk.cli.agent_test_runner import test_agent_replay as _test_agent_replay
+from google.adk.cli.utils.agent_loader import AgentLoader
 from google.genai import types
 import pytest
 
 CONTRIBUTING_DIR = Path(__file__).parent.parent.parent / "contributing"
+SAMPLES_DIR = CONTRIBUTING_DIR / "samples"
+
+
+@pytest.fixture(autouse=True)
+def _load_samples_like_adk_run():
+  """Loads samples with the YAML key denylist off, matching `adk run`.
+
+  The denylist is a hosted-web-server guard that fast_api enables globally and
+  never resets, so a fast_api test earlier in the process would otherwise leave
+  it on and block valid config samples here.
+  """
+  saved = config_agent_utils._ENFORCE_YAML_KEY_DENYLIST
+  config_agent_utils._set_enforce_yaml_key_denylist(False)
+  try:
+    yield
+  finally:
+    config_agent_utils._set_enforce_yaml_key_denylist(saved)
 
 
 def get_test_files():
@@ -57,3 +78,154 @@ def get_test_files():
 def test_sample(sample_dir: Path, test_file: Path, monkeypatch):
   """Tests a sample by replaying exported session events."""
   _test_agent_replay(sample_dir, test_file, monkeypatch)
+
+
+# Samples that cannot be loaded offline: they reach an external service, need an
+# optional dependency outside [all], or are not an independently loadable root.
+SKIP_LOAD = {
+    "integrations/agent_registry_agent": "calls Agent Registry API at import",
+    "integrations/api_registry_agent": "calls Cloud API Registry at import",
+    "integrations/application_integration_agent": (
+        "calls Integration Connectors API at import"
+    ),
+    "integrations/integration_connector_euc_agent": (
+        "calls Integration Connectors API at import"
+    ),
+    "multimodal/static_non_text_content": (
+        "uploads a file via the genai API at import"
+    ),
+    "integrations/authn-adk-all-in-one/adk_agents/agent_openapi_tools": (
+        "needs a local identity provider server on :5000"
+    ),
+    "mcp/mcp_postgres_agent": (
+        "needs POSTGRES_CONNECTION_STRING and a postgres server"
+    ),
+    "code_execution/custom_code_execution": (
+        "provisions a Vertex code-interpreter extension at import"
+    ),
+    "code_execution/vertex_code_execution": (
+        "provisions a Vertex code-interpreter extension at import"
+    ),
+    "integrations/crewai_tool_kwargs": (
+        "needs the crewai package (not installed on every Python version)"
+    ),
+    "integrations/files_retrieval_agent": (
+        "needs the llama-index-embeddings-google-genai package"
+    ),
+    "integrations/toolbox_agent": (
+        "needs the toolbox-adk package and a toolbox server"
+    ),
+    "multimodal/computer_use": "needs the playwright package",
+    "integrations/gepa": "experiment package, exposes no root_agent",
+    "integrations/slack_agent": (
+        "builds its agent inside main(), no module-level root_agent"
+    ),
+    "adk_team/adk_documentation": (
+        "package dir; its child agents are the samples"
+    ),
+    "adk_team/adk_answering_agent/gemini_assistant": (
+        "sub-agent of adk_answering_agent, not independently loadable"
+    ),
+    "integrations/oauth_calendar_agent": (
+        "fetches the Calendar API (calendar v3) discovery doc at import"
+    ),
+}
+
+# Samples whose own code is currently broken against the ADK API. Loading them
+# fails today; remove the entry once the sample is fixed.
+XFAIL_LOAD = {
+    "integrations/jira_agent": (
+        "ApplicationIntegrationToolset no longer accepts tool_name"
+    ),
+    "workflows/loop_config": (
+        "root_agent.yaml references the nonexistent agent_class Workflow"
+    ),
+    "models/hello_world_litellm_add_function_to_prompt": (
+        "langchain_core requires an explicit import of langchain_core.tools"
+    ),
+    "adk_team/adk_triaging_agent": (
+        "agent.py imports adk_triaging_agent.settings, which is not present"
+    ),
+}
+
+_DUMMY_ENV = {
+    "GOOGLE_API_KEY": "dummy-key",
+    "GEMINI_API_KEY": "dummy-key",
+    "GOOGLE_CLOUD_PROJECT": "dummy-project",
+    "GOOGLE_CLOUD_LOCATION": "us-central1",
+    "OPENAI_API_KEY": "dummy-key",
+    "ANTHROPIC_API_KEY": "dummy-key",
+    "GITHUB_TOKEN": "dummy-token",
+    "VERTEXAI_DATASTORE_ID": "dummy-datastore",
+}
+
+
+def get_sample_dirs():
+  """Yields a pytest param per loadable sample directory."""
+  if not SAMPLES_DIR.exists():
+    return
+  sample_dirs = []
+  for dirpath, dirnames, filenames in os.walk(SAMPLES_DIR):
+    path = Path(dirpath)
+    if path.name == "tests":
+      dirnames[:] = []
+      continue
+    if any(
+        f in filenames for f in ("agent.py", "__init__.py", "root_agent.yaml")
+    ):
+      sample_dirs.append(path)
+  for sample_dir in sorted(sample_dirs):
+    rel = sample_dir.relative_to(SAMPLES_DIR).as_posix()
+    if rel in SKIP_LOAD:
+      marks = pytest.mark.skip(reason=SKIP_LOAD[rel])
+    elif rel in XFAIL_LOAD:
+      marks = pytest.mark.xfail(reason=XFAIL_LOAD[rel], strict=False)
+    else:
+      marks = ()
+    yield pytest.param(sample_dir, id=rel, marks=marks)
+
+
+def _load_root_agent(sample_dir: Path):
+  """Loads a sample the way `adk run` does, isolating module side effects."""
+  saved_modules = set(sys.modules)
+  saved_path = list(sys.path)
+  sys.path.insert(0, str(sample_dir.parent))
+  try:
+    loader = AgentLoader(str(sample_dir.parent))
+    loader.remove_agent_from_cache(sample_dir.name)
+    agent_or_app = loader.load_agent(sample_dir.name)
+    return (
+        agent_or_app.root_agent
+        if isinstance(agent_or_app, App)
+        else agent_or_app
+    )
+  finally:
+    sys.path[:] = saved_path
+    # Evict only the sample's own modules so the next sample reloads cleanly,
+    # while leaving third-party libraries cached (re-importing libraries with
+    # global registries, e.g. opentelemetry, breaks on reload).
+    prefix = sample_dir.name
+    for name in set(sys.modules) - saved_modules:
+      module = sys.modules.get(name)
+      file = getattr(module, "__file__", None)
+      if (
+          name == prefix
+          or name.startswith(prefix + ".")
+          or (
+              file
+              and Path(file).resolve().is_relative_to(SAMPLES_DIR.resolve())
+          )
+      ):
+        del sys.modules[name]
+
+
+@pytest.mark.parametrize("sample_dir", list(get_sample_dirs()))
+def test_sample_loads(sample_dir: Path, monkeypatch):
+  """Smoke test: every sample's agent imports and constructs a root agent."""
+  for key, value in _DUMMY_ENV.items():
+    monkeypatch.setenv(key, value)
+  root_agent = _load_root_agent(sample_dir)
+  assert root_agent is not None, f"{sample_dir} loaded no root agent"
+  assert getattr(
+      root_agent, "name", None
+  ), f"{sample_dir} root agent has no name"