Added test

Author: radarhere

Tests/test_imagegrab.py

@@ -119,3 +119,15 @@ def test_grabclipboard_wl_clipboard(self, ext):
             subprocess.call(["wl-copy"], stdin=fp)
         im = ImageGrab.grabclipboard()
         assert_image_equal_tofile(im, image_path)
+
+    @pytest.mark.skipif(
+        (
+            sys.platform != "linux"
+            or not all(shutil.which(cmd) for cmd in ("wl-paste", "wl-copy"))
+        ),
+        reason="Linux with wl-clipboard only",
+    )
+    @pytest.mark.parametrize("arg", ("text", "--clear"))
+    def test_grabclipboard_wl_clipboard_errors(self, arg):
+        subprocess.call(["wl-copy", arg])
+        assert ImageGrab.grabclipboard() is None

src/PIL/ImageGrab.py

@@ -162,7 +162,11 @@ def grabclipboard():
             for silent_error in [
                 # wl-paste, when the clipboard is empty
                 b"Nothing is copied",
-                # wl-paste/debian xclip, when an image isn't available
+                # Ubuntu/Debian wl-paste, when the clipboard is empty
+                b"No selection",
+                # Ubuntu/Debian wl-paste, when an image isn't available
+                b"No suitable type of content copied",
+                # wl-paste or Ubuntu/Debian xclip, when an image isn't available
                 b" not available",
                 # xclip, when an image isn't available
                 b"cannot convert ",