diff --git a/tests/data/cloud_sdk.cfg b/tests/data/cloud_sdk.cfg
deleted file mode 100644
index 089aac5..0000000
--- a/tests/data/cloud_sdk.cfg
+++ /dev/null
@@ -1,2 +0,0 @@
-[core]
-project = example-project
diff --git a/tests/data/cloud_sdk_config.json b/tests/data/cloud_sdk_config.json
new file mode 100644
index 0000000..a5fe4a9
--- /dev/null
+++ b/tests/data/cloud_sdk_config.json
@@ -0,0 +1,19 @@
+{
+  "configuration": {
+    "active_configuration": "default",
+    "properties": {
+      "core": {
+        "account": "user@example.com",
+        "disable_usage_reporting": "False",
+        "project": "example-project"
+      }
+    }
+  },
+  "credential": {
+    "access_token": "don't use me",
+    "token_expiry": "2017-03-23T23:09:49Z"
+  },
+  "sentinels": {
+    "config_sentinel": "/Users/example/.config/gcloud/config_sentinel"
+  }
+}
diff --git a/tests/test__cloud_sdk.py b/tests/test__cloud_sdk.py
index ba72072..482a7ed 100644
--- a/tests/test__cloud_sdk.py
+++ b/tests/test__cloud_sdk.py
@@ -12,11 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import io
 import json
 import os
+import subprocess
 
 import mock
-import py
 import pytest
 
 from google.auth import _cloud_sdk
@@ -27,76 +28,52 @@
 DATA_DIR = os.path.join(os.path.dirname(__file__), 'data')
 AUTHORIZED_USER_FILE = os.path.join(DATA_DIR, 'authorized_user.json')
 
-with open(AUTHORIZED_USER_FILE) as fh:
+with io.open(AUTHORIZED_USER_FILE) as fh:
     AUTHORIZED_USER_FILE_DATA = json.load(fh)
 
 SERVICE_ACCOUNT_FILE = os.path.join(DATA_DIR, 'service_account.json')
 
-with open(SERVICE_ACCOUNT_FILE) as fh:
+with io.open(SERVICE_ACCOUNT_FILE) as fh:
     SERVICE_ACCOUNT_FILE_DATA = json.load(fh)
 
-with open(os.path.join(DATA_DIR, 'cloud_sdk.cfg')) as fh:
-    CLOUD_SDK_CONFIG_DATA = fh.read()
+with io.open(os.path.join(DATA_DIR, 'cloud_sdk_config.json'), 'rb') as fh:
+    CLOUD_SDK_CONFIG_FILE_DATA = fh.read()
 
-CONFIG_PATH_PATCH = mock.patch(
+
+@mock.patch(
+    'subprocess.check_output', autospec=True,
+    return_value=CLOUD_SDK_CONFIG_FILE_DATA)
+def test_get_project_id(check_output_mock):
+    project_id = _cloud_sdk.get_project_id()
+    assert project_id == 'example-project'
+
+
+@mock.patch(
+    'subprocess.check_output', autospec=True,
+    side_effect=subprocess.CalledProcessError(-1, None))
+def test_get_project_id_call_error(check_output_mock):
+    project_id = _cloud_sdk.get_project_id()
+    assert project_id is None
+
+
+@mock.patch(
+    'subprocess.check_output', autospec=True,
+    return_value=b'I am some bad json')
+def test_get_project_id_bad_json(check_output_mock):
+    project_id = _cloud_sdk.get_project_id()
+    assert project_id is None
+
+
+@mock.patch(
+    'subprocess.check_output', autospec=True,
+    return_value=b'{}')
+def test_get_project_id_missing_value(check_output_mock):
+    project_id = _cloud_sdk.get_project_id()
+    assert project_id is None
+
+
+@mock.patch(
     'google.auth._cloud_sdk.get_config_path', autospec=True)
-
-
-@pytest.fixture
-def config_dir(tmpdir):
-    config_dir = tmpdir.join(
-        '.config', _cloud_sdk._CONFIG_DIRECTORY)
-
-    with CONFIG_PATH_PATCH as mock_get_config_dir:
-        mock_get_config_dir.return_value = str(config_dir)
-        yield config_dir
-
-
-@pytest.fixture
-def config_file(config_dir):
-    config_file = py.path.local(_cloud_sdk._get_config_file(
-        str(config_dir), 'default'))
-    yield config_file
-
-
-def test_get_project_id(config_file):
-    config_file.write(CLOUD_SDK_CONFIG_DATA, ensure=True)
-    project_id = _cloud_sdk.get_project_id()
-    assert project_id == 'example-project'
-
-
-def test_get_project_id_non_existent(config_file):
-    project_id = _cloud_sdk.get_project_id()
-    assert project_id is None
-
-
-def test_get_project_id_bad_file(config_file):
-    config_file.write('<<<badconfig', ensure=True)
-    project_id = _cloud_sdk.get_project_id()
-    assert project_id is None
-
-
-def test_get_project_id_no_section(config_file):
-    config_file.write('[section]', ensure=True)
-    project_id = _cloud_sdk.get_project_id()
-    assert project_id is None
-
-
-def test_get_project_id_non_default_config(config_dir):
-    active_config = config_dir.join('active_config')
-    test_config = py.path.local(_cloud_sdk._get_config_file(
-        str(config_dir), 'test'))
-
-    # Create an active config file that points to the 'test' config.
-    active_config.write('test', ensure=True)
-    test_config.write(CLOUD_SDK_CONFIG_DATA, ensure=True)
-
-    project_id = _cloud_sdk.get_project_id()
-
-    assert project_id == 'example-project'
-
-
-@CONFIG_PATH_PATCH
 def test_get_application_default_credentials_path(mock_get_config_dir):
     config_path = 'config_path'
     mock_get_config_dir.return_value = config_path
diff --git a/tests/test__default.py b/tests/test__default.py
index a317e0a..001a19c 100644
--- a/tests/test__default.py
+++ b/tests/test__default.py
@@ -38,9 +38,6 @@
 with open(SERVICE_ACCOUNT_FILE) as fh:
     SERVICE_ACCOUNT_FILE_DATA = json.load(fh)
 
-with open(os.path.join(DATA_DIR, 'cloud_sdk.cfg')) as fh:
-    CLOUD_SDK_CONFIG_DATA = fh.read()
-
 LOAD_FILE_PATCH = mock.patch(
     'google.auth._default._load_credentials_from_file', return_value=(
         mock.sentinel.credentials, mock.sentinel.project_id), autospec=True)