tests: ensure systests pass under emulator in a clean environment

.github/workflows/system_emulated.yml

@@ -0,0 +1,29 @@
+name: "Run systests on emulator"
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+
+  run-systests:
+    runs-on: ubuntu-20.04
+
+    steps:
+
+    - name: Checkout
+      uses: actions/checkout@v2
+
+    - name: Setup Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.7'
+
+    - name: Setup GCloud SDK
+      uses: google-github-actions/setup-gcloud@v0.2.1
+
+    - name: Install / run Nox
+      run: |
+        python -m pip install --upgrade setuptools pip
+        python -m pip install nox
+        nox -s system_emulated

google/cloud/firestore_v1/base_client.py

@@ -27,6 +27,7 @@
 import os
 import grpc  # type: ignore
 
+from google.auth.credentials import AnonymousCredentials
 import google.api_core.client_options  # type: ignore
 import google.api_core.path_template  # type: ignore
 from google.api_core import retry as retries  # type: ignore
@@ -61,6 +62,7 @@
 
 DEFAULT_DATABASE = "(default)"
 """str: The default database used in a :class:`~google.cloud.firestore_v1.client.Client`."""
+_DEFAULT_EMULATOR_PROJECT = "google-cloud-firestore-emulator"
 _BAD_OPTION_ERR = (
     "Exactly one of ``last_update_time`` or ``exists`` " "must be provided."
 )
@@ -122,6 +124,14 @@ def __init__(
         # NOTE: This API has no use for the _http argument, but sending it
         #       will have no impact since the _http() @property only lazily
         #       creates a working HTTP object.
+        self._emulator_host = os.getenv(_FIRESTORE_EMULATOR_HOST)
+
+        if self._emulator_host is not None:
+            if credentials is None:
+                credentials = AnonymousCredentials()
+            if project is None:
+                project = _DEFAULT_EMULATOR_PROJECT
+
         super(BaseClient, self).__init__(
             project=project,
             credentials=credentials,
@@ -137,7 +147,6 @@ def __init__(
         self._client_options = client_options
 
         self._database = database
-        self._emulator_host = os.getenv(_FIRESTORE_EMULATOR_HOST)
 
     def _firestore_api_helper(self, transport, client_class, client_module) -> Any:
         """Lazy-loading getter GAPIC Firestore API.

noxfile.py

@@ -37,6 +37,7 @@
 # 'docfx' is excluded since it only needs to run in 'docs-presubmit'
 nox.options.sessions = [
     "unit",
+    "system_emulated",
     "system",
     "cover",
     "lint",
@@ -128,6 +129,44 @@ def unit(session):
     default(session)
 
 
+@nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)
+def system_emulated(session):
+    import subprocess
+    import signal
+
+    try:
+        subprocess.call(["gcloud", "--version"])
+    except OSError:
+        session.skip("gcloud not found but required for emulator support")
+
+    # Currently, CI/CD doesn't have beta component of gcloud.
+    subprocess.call(
+        ["gcloud", "components", "install", "beta", "cloud-firestore-emulator",]
+    )
+
+    hostport = "localhost:8789"
+    session.env["FIRESTORE_EMULATOR_HOST"] = hostport
+
+    p = subprocess.Popen(
+        [
+            "gcloud",
+            "--quiet",
+            "beta",
+            "emulators",
+            "firestore",
+            "start",
+            "--host-port",
+            hostport,
+        ]
+    )
+
+    try:
+        system(session)
+    finally:
+        # Stop Emulator
+        os.killpg(os.getpgid(p.pid), signal.SIGKILL)
+
+
 @nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)
 def system(session):
     """Run the system test suite."""

owlbot.py

@@ -143,6 +143,76 @@ def update_fixup_scripts(library):
 
 s.move(templated_files)
 
+# ----------------------------------------------------------------------------
+# Customize noxfile.py
+# ----------------------------------------------------------------------------
+
+def place_before(path, text, *before_text, escape=None):
+    replacement = "\n".join(before_text) + "\n" + text
+    if escape:
+        for c in escape:
+            text = text.replace(c, '\\' + c)
+    s.replace([path], text, replacement)
+
+system_emulated_session = """
+@nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)
+def system_emulated(session):
+    import subprocess
+    import signal
+
+    try:
+        subprocess.call(["gcloud", "--version"])
+    except OSError:
+        session.skip("gcloud not found but required for emulator support")
+
+    # Currently, CI/CD doesn't have beta component of gcloud.
+    subprocess.call(
+        ["gcloud", "components", "install", "beta", "cloud-firestore-emulator",]
+    )
+
+    hostport = "localhost:8789"
+    session.env["FIRESTORE_EMULATOR_HOST"] = hostport
+
+    p = subprocess.Popen(
+        [
+            "gcloud",
+            "--quiet",
+            "beta",
+            "emulators",
+            "firestore",
+            "start",
+            "--host-port",
+            hostport,
+        ]
+    )
+
+    try:
+        system(session)
+    finally:
+        # Stop Emulator
+        os.killpg(os.getpgid(p.pid), signal.SIGKILL)
+
+"""
+
+place_before(
+    "noxfile.py",
+    "@nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)\n"
+    "def system(session):",
+    system_emulated_session,
+    escape="()"
+)
+
+# add system_emulated nox session
+s.replace("noxfile.py",
+    """nox.options.sessions = \[
+    "unit",
+    "system",""",
+    """nox.options.sessions = [
+    "unit",
+    "system_emulated",
+    "system",""",
+)
+
 s.replace(
     "noxfile.py",
     """\"--quiet\",

tests/unit/v1/test_async_client.py

@@ -51,18 +51,6 @@ def test_constructor(self):
         self.assertEqual(client._credentials, credentials)
         self.assertEqual(client._database, DEFAULT_DATABASE)
         self.assertIs(client._client_info, _CLIENT_INFO)
-        self.assertIsNone(client._emulator_host)
-
-    def test_constructor_with_emulator_host(self):
-        from google.cloud.firestore_v1.base_client import _FIRESTORE_EMULATOR_HOST
-
-        credentials = _make_credentials()
-        emulator_host = "localhost:8081"
-        with mock.patch("os.getenv") as getenv:
-            getenv.return_value = emulator_host
-            client = self._make_one(project=self.PROJECT, credentials=credentials)
-            self.assertEqual(client._emulator_host, emulator_host)
-            getenv.assert_called_once_with(_FIRESTORE_EMULATOR_HOST)
 
     def test_constructor_explicit(self):
         from google.api_core.client_options import ClientOptions

tests/unit/v1/test_base_client.py

@@ -37,6 +37,46 @@ def _make_default_one(self):
         credentials = _make_credentials()
         return self._make_one(project=self.PROJECT, credentials=credentials)
 
+    def test_constructor_with_emulator_host_defaults(self):
+        from google.auth.credentials import AnonymousCredentials
+        from google.cloud.firestore_v1.base_client import _DEFAULT_EMULATOR_PROJECT
+        from google.cloud.firestore_v1.base_client import _FIRESTORE_EMULATOR_HOST
+
+        emulator_host = "localhost:8081"
+
+        with mock.patch("os.environ", {_FIRESTORE_EMULATOR_HOST: emulator_host}):
+            client = self._make_one()
+
+        self.assertEqual(client._emulator_host, emulator_host)
+        self.assertIsInstance(client._credentials, AnonymousCredentials)
+        self.assertEqual(client.project, _DEFAULT_EMULATOR_PROJECT)
+
+    def test_constructor_with_emulator_host_w_project(self):
+        from google.auth.credentials import AnonymousCredentials
+        from google.cloud.firestore_v1.base_client import _FIRESTORE_EMULATOR_HOST
+
+        emulator_host = "localhost:8081"
+
+        with mock.patch("os.environ", {_FIRESTORE_EMULATOR_HOST: emulator_host}):
+            client = self._make_one(project=self.PROJECT)
+
+        self.assertEqual(client._emulator_host, emulator_host)
+        self.assertIsInstance(client._credentials, AnonymousCredentials)
+
+    def test_constructor_with_emulator_host_w_creds(self):
+        from google.cloud.firestore_v1.base_client import _DEFAULT_EMULATOR_PROJECT
+        from google.cloud.firestore_v1.base_client import _FIRESTORE_EMULATOR_HOST
+
+        credentials = _make_credentials()
+        emulator_host = "localhost:8081"
+
+        with mock.patch("os.environ", {_FIRESTORE_EMULATOR_HOST: emulator_host}):
+            client = self._make_one(credentials=credentials)
+
+        self.assertEqual(client._emulator_host, emulator_host)
+        self.assertIs(client._credentials, credentials)
+        self.assertEqual(client.project, _DEFAULT_EMULATOR_PROJECT)
+
     @mock.patch(
         "google.cloud.firestore_v1.services.firestore.client.FirestoreClient",
         autospec=True,

tests/unit/v1/test_client.py

@@ -49,18 +49,6 @@ def test_constructor(self):
         self.assertEqual(client._credentials, credentials)
         self.assertEqual(client._database, DEFAULT_DATABASE)
         self.assertIs(client._client_info, _CLIENT_INFO)
-        self.assertIsNone(client._emulator_host)
-
-    def test_constructor_with_emulator_host(self):
-        from google.cloud.firestore_v1.base_client import _FIRESTORE_EMULATOR_HOST
-
-        credentials = _make_credentials()
-        emulator_host = "localhost:8081"
-        with mock.patch("os.getenv") as getenv:
-            getenv.return_value = emulator_host
-            client = self._make_one(project=self.PROJECT, credentials=credentials)
-            self.assertEqual(client._emulator_host, emulator_host)
-            getenv.assert_called_once_with(_FIRESTORE_EMULATOR_HOST)
 
     def test_constructor_explicit(self):
         from google.api_core.client_options import ClientOptions