test: add more integration tests with insta. Like it!

tests/assets/mixin-module.scss

@@ -0,0 +1,24 @@
+
+@mixin surface($color: black){
+    @if $color == black{
+        color: white;
+        background-color: green;
+    }@else if $color == white{
+        color: red;
+        background-color: black;
+    }@else{
+        color: #c6c6c6;
+        background-color: #00ffff;
+    }
+    &::after{
+        content: 'Colored';
+        color: $color;
+        background-color: blue;
+        &:hover{
+            transform: scale(2);
+        }
+    }
+    &:hover{
+        transform: translateX(10%);
+    }
+}