Merge pull request #906 from hugovk/ImageGrab

Improve error message for ImageGrab on non-Windows

PIL/ImageGrab.py

@@ -17,6 +17,9 @@
 
 from PIL import Image
 
+import sys
+if sys.platform != "win32":
+    raise ImportError("ImageGrab is Windows only")
 
 try:
     # built-in driver (1.1.3 and later)
@@ -40,7 +43,7 @@ def grab(bbox=None):
 
 
 def grabclipboard():
-    debug = 0 # temporary interface
+    debug = 0  # temporary interface
     data = Image.core.grabclipboard(debug)
     if isinstance(data, bytes):
         from PIL import BmpImagePlugin

Tests/test_imagegrab.py

@@ -1,5 +1,7 @@
 from helper import unittest, PillowTestCase
 
+import sys
+
 try:
     from PIL import ImageGrab
 
@@ -19,6 +21,27 @@ except ImportError:
             self.skipTest("ImportError")
 
 
+class TestImageGrabImport(PillowTestCase):
+
+    def test_import(self):
+        # Arrange
+        exception = None
+
+        # Act
+        try:
+            from PIL import ImageGrab
+            ImageGrab.__name__  # dummy to prevent Pyflakes warning
+        except Exception as e:
+            exception = e
+
+        # Assert
+        if sys.platform == 'win32':
+            self.assertIsNone(exception, None)
+        else:
+            self.assertIsInstance(exception, ImportError)
+            self.assertEqual(str(exception), "ImageGrab is Windows only")
+
+
 if __name__ == '__main__':
     unittest.main()