tabler/core/scss/tests/_add-subtract.test.scss

// Priority 1 — unit tests for `add()` and `subtract()` from
// scss/mixins/_functions.scss. Both guard against `null` operands and fall back
// to a `calc()` expression when the operands are unit-incompatible, so the
// branches around null-handling and the numeric-vs-calc path are what matter.

@use 'sass:meta';
@use 'sass:string';
@use '../mixins/functions' as *;

@include describe('add') {
  @include it('treats a null operand as the identity') {
    @include assert-equal(add(null, 5px), 5px);
    @include assert-equal(add(5px, null), 5px);
  }

  @include it('adds two compatible numbers directly') {
    @include assert-equal(add(2px, 3px), 5px);
  }

  // add() returns a real `calculation` here; two structurally-identical
  // calculations aren't `==` in Sass, so compare the rendered output instead.
  @include it('falls back to calc() for incompatible units') {
    @include assert-equal(meta.inspect(add(2px, 3%)), 'calc(2px + 3%)');
  }

  @include it('builds a plain expression when calc is disabled') {
    @include assert-equal(add(2px, 3%, false), string.unquote('2px + 3%'));
  }
}

@include describe('subtract') {
  @include it('returns null when both operands are null') {
    @include assert-equal(subtract(null, null), null);
  }

  @include it('handles a single null operand') {
    @include assert-equal(subtract(5px, null), 5px);
    @include assert-equal(subtract(null, 5px), -5px);
  }

  @include it('subtracts two compatible numbers directly') {
    @include assert-equal(subtract(5px, 2px), 3px);
  }

  @include it('falls back to calc() for incompatible units') {
    @include assert-equal(meta.inspect(subtract(5px, 2%)), 'calc(5px - 2%)');
  }
}