TST: Add unit tests for pandas_gbq.auth.get_credentials(). (googleapis#184)

* TST: Add unit tests for pandas_gbq.auth.get_credentials().

Tests (actual auth mocked out):
* Using private key with contents.
* Using private key with path.
* Using default credentials.
* Using cached user credentials.

* TST: Use classmethod decorator for mocked methods.

See: https://stackoverflow.com/a/29235090/101923

Author: tswast

pandas_gbq/auth.py

@@ -39,8 +39,10 @@ def get_service_account_credentials(private_key):
     import google.auth.transport.requests
     from google.oauth2.service_account import Credentials
 
+    is_path = os.path.isfile(private_key)
+
     try:
-        if os.path.isfile(private_key):
+        if is_path:
             with open(private_key) as f:
                 json_key = json.loads(f.read())
         else:
@@ -64,11 +66,13 @@ def get_service_account_credentials(private_key):
         return credentials, json_key.get('project_id')
     except (KeyError, ValueError, TypeError, AttributeError):
         raise pandas_gbq.exceptions.InvalidPrivateKeyFormat(
-            "Private key is missing or invalid. It should be service "
-            "account private key JSON (file path or string contents) "
-            "with at least two keys: 'client_email' and 'private_key'. "
-            "Can be obtained from: https://console.developers.google."
-            "com/permissions/serviceaccounts")
+            'Detected private_key as {}. '.format(
+                'path' if is_path else 'contents') +
+            'Private key is missing or invalid. It should be service '
+            'account private key JSON (file path or string contents) '
+            'with at least two keys: "client_email" and "private_key". '
+            'Can be obtained from: https://console.developers.google.'
+            'com/permissions/serviceaccounts')
 
 
 def get_application_default_credentials(project_id=None):

tests/data/dummy_key.json

@@ -0,0 +1,5 @@
+
+    {
+        "private_key": "some_key",
+        "client_email": "[email protected]"
+    }

tests/unit/test_auth.py

@@ -0,0 +1,102 @@
+# -*- coding: utf-8 -*-
+
+import json
+import os.path
+
+try:
+    import mock
+except ImportError:  # pragma: NO COVER
+    from unittest import mock
+
+from pandas_gbq import auth
+
+
+def test_get_credentials_private_key_contents(monkeypatch):
+    from google.oauth2 import service_account
+
+    @classmethod
+    def from_service_account_info(cls, key_info):
+        mock_credentials = mock.create_autospec(cls)
+        mock_credentials.with_scopes.return_value = mock_credentials
+        mock_credentials.refresh.return_value = mock_credentials
+        return mock_credentials
+
+    monkeypatch.setattr(
+        service_account.Credentials,
+        'from_service_account_info',
+        from_service_account_info)
+    private_key = json.dumps({
+        'private_key': 'some_key',
+        'client_email': '[email protected]',
+        'project_id': 'private-key-project'
+    })
+    credentials, project = auth.get_credentials(private_key=private_key)
+
+    assert credentials is not None
+    assert project == 'private-key-project'
+
+
+def test_get_credentials_private_key_path(monkeypatch):
+    from google.oauth2 import service_account
+
+    @classmethod
+    def from_service_account_info(cls, key_info):
+        mock_credentials = mock.create_autospec(cls)
+        mock_credentials.with_scopes.return_value = mock_credentials
+        mock_credentials.refresh.return_value = mock_credentials
+        return mock_credentials
+
+    monkeypatch.setattr(
+        service_account.Credentials,
+        'from_service_account_info',
+        from_service_account_info)
+    private_key = os.path.join(
+        os.path.dirname(__file__), '..', 'data', 'dummy_key.json')
+    credentials, project = auth.get_credentials(private_key=private_key)
+
+    assert credentials is not None
+    assert project is None
+
+
+def test_get_credentials_default_credentials(monkeypatch):
+    import google.auth
+    import google.auth.credentials
+    import google.cloud.bigquery
+
+    def mock_default_credentials(scopes=None, request=None):
+        return (
+            mock.create_autospec(google.auth.credentials.Credentials),
+            'default-project',
+        )
+
+    monkeypatch.setattr(google.auth, 'default', mock_default_credentials)
+    mock_client = mock.create_autospec(google.cloud.bigquery.Client)
+    monkeypatch.setattr(google.cloud.bigquery, 'Client', mock_client)
+
+    credentials, project = auth.get_credentials()
+    assert project == 'default-project'
+    assert credentials is not None
+
+
+def test_get_credentials_load_user_no_default(monkeypatch):
+    import google.auth
+    import google.auth.credentials
+
+    def mock_default_credentials(scopes=None, request=None):
+        return (None, None)
+
+    monkeypatch.setattr(google.auth, 'default', mock_default_credentials)
+    mock_user_credentials = mock.create_autospec(
+        google.auth.credentials.Credentials)
+
+    def mock_load_credentials(project_id=None, credentials_path=None):
+        return mock_user_credentials
+
+    monkeypatch.setattr(
+        auth,
+        'load_user_account_credentials',
+        mock_load_credentials)
+
+    credentials, project = auth.get_credentials()
+    assert project is None
+    assert credentials is mock_user_credentials