Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.11)
// Compass (v1.0.3)
// ----

@mixin svg-pro (
  $filename,
  $svg-class,
  $no-svg-class: "lt-ie9") {

  @if $svg-class {
    background-image: image-url($filename + ".png");
    .#{$svg-class} & {
      background-image: image-url($filename + ".svg");
    }
  }
  @else {
    background-image: image-url($filename + ".svg");
    .#{$no-svg-class} & {
      background-image: image-url($filename + ".png");
    }
  }
}
.test {
  @include svg-pro("logo", $svg-class: "svg");
}

SassMeister-output.css

.test {
  background-image: url('/images/logo.png');
}
.svg .test {
  background-image: url('/images/logo.svg');
}