Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.13)
// Compass (v1.0.3)
// ----

$color: null ;
$a: 1;
@mixin getMixin {
  .foreground {
    background: $a;
    @if variable-exists(color) {
      background: $color;
    }
  }
}

$color-scheme: blue;
@if $color-scheme == blue {
    .blue {
      $a: 2;
      $color: #000;
      @include getMixin;
    }
}

$color-scheme: red;
@if $color-scheme == red {
    .red {
      $a: 3;
      $color: null;
      @include getMixin;
    }
}

SassMeister-output.css

.blue .foreground {
  background: 2;
  background: #000;
}

.red .foreground {
  background: 3;
}