Handle optional import where imported module raises exception on impo…

…rt (#1192)

* Handle optional import where imported module raises exception on import. Log exception but don't raise

plotly/optional_imports.py

@@ -5,7 +5,9 @@
 from __future__ import absolute_import
 
 from importlib import import_module
+import logging
 
+logger = logging.getLogger(__name__)
 _not_importable = set()
 
 
@@ -23,3 +25,7 @@ def get_module(name):
             return import_module(name)
         except ImportError:
             _not_importable.add(name)
+        except Exception as e:
+            _not_importable.add(name)
+            msg = "Error importing optional module {}".format(name)
+            logger.exception(msg)

plotly/tests/test_core/test_optional_imports/exploding_module.py

@@ -0,0 +1,2 @@
+# A module that raises and exception on import
+raise Exception("Boom!")

plotly/tests/test_core/test_optional_imports/test_optional_imports.py

@@ -1,7 +1,6 @@
 from __future__ import absolute_import
-
+import sys
 from unittest import TestCase
-
 from plotly.optional_imports import get_module
 
 
@@ -22,3 +21,33 @@ def test_get_module_exists_submodule(self):
     def test_get_module_does_not_exist(self):
         module = get_module('hoopla')
         self.assertIsNone(module)
+
+    def test_get_module_import_exception(self):
+        # Get module that raises an exception on import
+        module_str = ('plotly.tests.test_core.'
+                      'test_optional_imports.exploding_module')
+
+        if sys.version_info.major == 3 and sys.version_info.minor >= 4:
+            with self.assertLogs('plotly.optional_imports', level='ERROR') as cm:
+                module = get_module(module_str)
+
+            # No exception should be raised and None should be returned
+            self.assertIsNone(module)
+
+            # Check logging level and log message
+            expected_start = ('ERROR:plotly.optional_imports:'
+                              'Error importing optional module ' + module_str)
+
+            self.assertEqual(
+                cm.output[0][:len(expected_start)], expected_start)
+
+            # Check that exception message is included after log message
+            expected_end = 'Boom!'
+            self.assertEqual(
+                cm.output[0][-len(expected_end):], expected_end)
+        else:
+            # Don't check logging
+            module = get_module(module_str)
+
+            # No exception should be raised and None should be returned
+            self.assertIsNone(module)