test: added

Author: alexander-akait

test/fixtures/webpackIgnore.css

@@ -157,3 +157,16 @@
         './url/img.png' 5x
     );
 }
+
+.class {
+  /*webpackIgnore:  true*/
+  background-image: image-set(
+    /*webpackIgnore:  false*/
+    url(./url/img.png) 2x,
+    /*webpackIgnore:  true*/
+    url(./url/img.png) 3x,
+    /*webpackIgnore:  false*/
+    url(./url/img.png) 4x,
+    url(./url/img.png) 5x
+  );
+}