Quelle  test_Color.js   Sprache: JAVA

"use strict";

const { Color } = ChromeUtils.importESModule(
  "resource://gre/modules/Color.sys.mjs"
);

function run_test() {
  testRelativeLuminance();
  testUseBrightText();
  testContrastRatio();
  testIsContrastRatioAcceptable();
}

function testRelativeLuminance() {
  let c = new Color(0, 0, 0);
  Assert.equal(c.relativeLuminance, 0, "Black is not illuminating");

  c = new Color(255, 255, 255);
  Assert.equal(c.relativeLuminance, 1, "White is quite the luminant one");

  c = new Color(142, 42, 142);
  Assert.equal(
    c.relativeLuminance,
    0.09359705837110571,
    "This purple is not that luminant"
  );
}

function testUseBrightText() {
  let c = new Color(0, 0, 0);
  Assert.ok(
    c.useBrightText,
    "Black is bright, so bright text should be used here"
  );

  c = new Color(255, 255, 255);
  Assert.ok(
    !c.useBrightText,
    "White is bright, so better not use bright colored text on it"
  );
}

function testContrastRatio() {
  let c = new Color(0, 0, 0);
  let c2 = new Color(255, 255, 255);
  Assert.equal(
    c.contrastRatio(c2),
    21,
    "Contrast between black and white is max"
  );
  Assert.equal(c.contrastRatio(c), 1, "Contrast between equals is min");

  let c3 = new Color(142, 42, 142);
  Assert.equal(
    c.contrastRatio(c3),
    2.871941167422114,
    "Contrast between black and purple shouldn't be very high"
  );
  Assert.equal(
    c2.contrastRatio(c3),
    7.312127503938331,
    "Contrast between white and purple should be high"
  );
}

function testIsContrastRatioAcceptable() {
  // Let's assert what browser.js is doing for window frames.
  let c = new Color(...[55, 156, 152]);
  let c2 = new Color(0, 0, 0);
  Assert.equal(c.r, 55, "Reds should match");
  Assert.equal(c.g, 156, "Greens should match");
  Assert.equal(c.b, 152, "Blues should match");
  Assert.ok(
    c.isContrastRatioAcceptable(c2),
    "The blue is high contrast enough"
  );
  c2 = new Color(...[35, 65, 100]);
  Assert.ok(
    !c.isContrastRatioAcceptable(c2),
    "The blue is not high contrast enough"
  );
  // But would it be high contrast enough at a lower conformance level?
  Assert.ok(
    c.isContrastRatioAcceptable(c2, "A"),
    "The blue is high contrast enough when used as large text"
  );
}