Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.2.17)
// Compass (v0.12.4)
// ----

$var: 1;

@mixin test($p: null) {
    @if ($p) {
        /* Do something if $p was 4passed?*/
    } @else {
        /* Do something if $p was not passed?*/
    }
}

test1 {
  @include test();
}
test2 {
  @include test($var);
}

SassMeister-output.css

test1 {
  /* Do something if $p was not passed?*/
}

test2 {
  /* Do something if $p was 4passed?*/
}