Mock call to AuthClient fetchCredentials() in tests

tests/test_files.py

@@ -2,7 +2,7 @@
 from unittest.mock import Mock
 from unittest.mock import patch
 
-from dapla import FileClient
+from dapla import FileClient, AuthClient
 
 PATH_WITH_PREFIX = "gs://bucket/path"
 PATH_WITHOUT_PREFIX = "bucket/path"
@@ -43,6 +43,8 @@ def test_get_versions_valid_file(self, mock_client: Mock) -> None:
             time_deleted=None,
         )
 
+        AuthClient.fetch_google_credentials = Mock(return_value="test_credentials")
+
         mock_client.return_value.list_blobs.return_value = [mock_blob1, mock_blob2]
 
         files = FileClient.get_versions(bucket_name, file_name)
@@ -58,6 +60,7 @@ def test_get_versions_empty_bucket(self, mock_client: Mock) -> None:
         bucket_name = "test-bucket"
         file_name = "test-file.txt"
         mock_client.return_value.list_blobs.return_value = []
+        AuthClient.fetch_google_credentials = Mock(return_value="test_credentials")
 
         files = FileClient.get_versions(bucket_name, file_name)
 
@@ -71,6 +74,7 @@ def test_get_versions_non_existent_file(self, mock_client: Mock) -> None:
         bucket_name = "test-bucket"
         file_name = "non-existent-file.txt"
         mock_client.return_value.list_blobs.return_value = []
+        AuthClient.fetch_google_credentials = Mock(return_value="test_credentials")
 
         files = FileClient.get_versions(bucket_name, file_name)
 
@@ -85,6 +89,7 @@ def test_restore_version_success(self, mock_client: Mock) -> None:
         mock_source_blob = Mock()
         mock_client.return_value.bucket.return_value = mock_bucket
         mock_bucket.blob.return_value = mock_source_blob
+        AuthClient.fetch_google_credentials = Mock(return_value="test_credentials")
 
         blob = FileClient.restore_version(
             bucket_name="test-bucket",
@@ -111,6 +116,7 @@ def test_restore_version_existing_live_version(self, mock_client: Mock) -> None:
         mock_source_blob = Mock()
         mock_client.return_value.bucket.return_value = mock_bucket
         mock_bucket.blob.return_value = mock_source_blob
+        AuthClient.fetch_google_credentials = Mock(return_value="test_credentials")
 
         blob = FileClient.restore_version(
             bucket_name="test-bucket",