qemu-iotests: Add _unsupported_fmt helper

This helper allows adding tests supporting any format expect the
specified formats. This may be useful to test that many formats behave
in a common way.

Signed-off-by: Nir Soffer <nirsof@gmail.com>
Message-id: 20170201003120.23378-3-nirsof@gmail.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

tests/qemu-iotests/common.rc

@@ -355,6 +355,17 @@ _supported_fmt()
     _notrun "not suitable for this image format: $IMGFMT"
 }
 
+# tests whether $IMGFMT is one of the unsupported image format for a test
+#
+_unsupported_fmt()
+{
+    for f; do
+        if [ "$f" = "$IMGFMT" ]; then
+            _notrun "not suitable for this image format: $IMGFMT"
+        fi
+    done
+}
+
 # tests whether $IMGPROTO is one of the supported image protocols for a test
 #
 _supported_proto()