from .base import LightningLoggerBase, rank_zero_only
from .test_tube_logger import TestTubeLogger

try:
    from .mlflow_logger import MLFlowLogger
except ModuleNotFoundError:
    pass

pytorch_lightning/logging/__init__.py
from .base import LightningLoggerBase, rank_zero_only

try:
    from .test_tube_logger import TestTubeLogger
except ModuleNotFoundError:
    pass
try:
    from .mlflow_logger import MLFlowLogger
except ModuleNotFoundError:
    pass

pytorch_lightning/logging/__init__.py
diff --git a/pytorch_lightning/logging/__init__.py b/pytorch_lightning/logging/__init__.py
index 89e3d43551128..b8e2fcff281bc 100644
--- a/pytorch_lightning/logging/__init__.py
+++ b/pytorch_lightning/logging/__init__.py
@@ -1,6 +1,9 @@
 from .base import LightningLoggerBase, rank_zero_only
-from .test_tube_logger import TestTubeLogger
 
+try:
+    from .test_tube_logger import TestTubeLogger
+except ModuleNotFoundError:
+    pass
 try:
     from .mlflow_logger import MLFlowLogger
 except ModuleNotFoundError:

Make test_tube optional
**Is your feature request related to a problem? Please describe.**
`test_tube` is only needed when using `TestTubeLogger`, thus it should not be an install requirement like `mlflow`.
