mock experiment if test-tube not installed

tests/deprecated_api/test_remove_1-7.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """ Test deprecated functionality which will be removed in v1.7.0 """
+from unittest import mock
 
 import pytest
 
@@ -90,6 +91,7 @@ def test_v1_7_0_trainer_prepare_data_per_node(tmpdir):
         _ = Trainer(prepare_data_per_node=False)
 
 
-def test_v1_7_0_test_tube_logger(tmpdir):
+@mock.patch("pytorch_lightning.loggers.test_tube.Experiment")
+def test_v1_7_0_test_tube_logger(_, tmpdir):
     with pytest.deprecated_call(match="The TestTubeLogger is deprecated since v1.5 and will be removed in v1.7"):
         _ = TestTubeLogger(tmpdir)