Add some test files

sample_files/css_after.css

@@ -0,0 +1,14 @@
+/* hello
+world */
+.bar {
+  margin: 0;
+}
+
+.foo1 {
+  margin: 0;
+  color: green;
+}
+
+.baz {
+  color: blue;
+}

sample_files/css_before.css

@@ -0,0 +1,13 @@
+/* hello
+world */
+.foo1 {
+  margin: 0;
+}
+
+.bar {
+  margin: 0;
+}
+
+.baz {
+  color: red;
+}