add some tests

google/auth/_default.py

@@ -225,11 +225,11 @@ def _get_from_credentials_file_path(file_path, quota_project_id=None):
         return None, None
 
 
-def get_api_key_credentials(api_key):
+def get_api_key_credentials(key):
     """Return credentials with the given API key."""
     from google.auth import api_key
 
-    return api_key.Credentials(api_key)
+    return api_key.Credentials(key)
 
 
 def _get_explicit_environ_credentials(quota_project_id=None):
@@ -241,13 +241,11 @@ def _get_explicit_environ_credentials(quota_project_id=None):
         raise exceptions.DefaultCredentialsError("{} is not a supported GOOGLE_ADC_FORMAT value".format(adc_format))
 
     if adc_format == "api_key":
-        from google.auth import api_key
-
-        return api_key.Credentials(adc_value), quota_project_id
+        return get_api_key_credentials(adc_value), quota_project_id
     elif adc_format == "token":
         from google.oauth2 import fixed_token_credentials
 
-        return fixed_token_credentials.credentials(adc_value), quota_project_id
+        return fixed_token_credentials.Credentials(adc_value), quota_project_id
     elif adc_format == "base64_json":
         try:
             json_str = base64.b64decode(adc_value, validate=True).decode("utf8")
@@ -260,7 +258,7 @@ def _get_explicit_environ_credentials(quota_project_id=None):
             six.raise_from(new_exc, caught_exc)
         return _load_credentials_from_info("JSON", json_content, quota_project_id=quota_project_id)
 
-    return _get_from_credentials_file_path(adc_value)
+    return _get_from_credentials_file_path(adc_value, quota_project_id=quota_project_id)
 
 
 def _get_gae_credentials():

google/auth/api_key.py

@@ -34,9 +34,9 @@ def __init__(self, token):
         Raises:
             ValueError: If the provided API key is not a non-empty string.
         """
+        super(Credentials, self).__init__()
         if not token:
             raise ValueError("Token must be a non-empty API key string")
-        super(Credentials, self).__init__()
         self.token = token
 
     @property

google/oauth2/fixed_token_credentials.py

@@ -23,7 +23,7 @@
 from google.auth import credentials
 
 
-class FixedTokenCredentials(credentials.Credentials):
+class Credentials(credentials.Credentials):
     """Credentials with a fixed OAuth2 token.
 
     The token is considered never expired so users are responsible for the
@@ -39,7 +39,7 @@ def __init__(self, token):
         """
         if not token:
             raise ValueError("Token is not provided")
-        super(FixedTokenCredentials, self).__init__()
+        super(Credentials, self).__init__()
         self.token = token
 
     @property

tests/test__default.py

@@ -19,6 +19,7 @@
 import pytest  # type: ignore
 
 from google.auth import _default
+from google.auth import api_key
 from google.auth import app_engine
 from google.auth import aws
 from google.auth import compute_engine
@@ -28,6 +29,7 @@
 from google.auth import external_account
 from google.auth import identity_pool
 from google.auth import impersonated_credentials
+from google.oauth2 import fixed_token_credentials
 from google.oauth2 import service_account
 import google.oauth2.credentials
 
@@ -1140,3 +1142,32 @@ def test_default_impersonated_service_account_set_both_scopes_and_default_scopes
 
     credentials, _ = _default.default(scopes=scopes, default_scopes=default_scopes)
     assert credentials._target_scopes == scopes
+
+
+def test_default_adc_format_unsupported():
+    with pytest.raises(exceptions.DefaultCredentialsError) as excinfo:
+        with mock.patch.dict(os.environ, {environment_vars.ADC_FORMAT: "unsupported"}):
+            _default.default()
+
+    assert excinfo.match("not a supported GOOGLE_ADC_FORMAT value")
+
+
+def test_default_adc_format_api_key():
+    with mock.patch.dict(os.environ, {environment_vars.ADC_FORMAT: "api_key"}):
+        with mock.patch.dict(os.environ, {environment_vars.CREDENTIALS: "key-foo"}):
+            cred, project_id = _default.default(quota_project_id="project-foo")
+
+    assert isinstance(cred, api_key.Credentials)
+    assert cred.token == "key-foo"
+    assert project_id == "project-foo"
+
+
+def test_default_adc_format_token():
+    with mock.patch.dict(os.environ, {environment_vars.ADC_FORMAT: "token"}):
+        with mock.patch.dict(os.environ, {environment_vars.CREDENTIALS: "token-foo"}):
+            cred, project_id = _default.default(quota_project_id="project-foo")
+
+    assert isinstance(cred, fixed_token_credentials.Credentials)
+    assert cred.token == "token-foo"
+    assert cred.valid
+    assert project_id == "project-foo"