source-relevant-mutations.html

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<!DOCTYPE html>

<title>img should only look at a parent picture element</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<picture>

  <source id=s1 media=all srcset="data:,s1">

  <source id=s2 media=all srcset="data:,s2">

  <source id=s3 media=all srcset="data:,s3">

  <img id=img1 src="data:,img1">

  <img id=img2 src="data:,img2">

  <source id=s4 media=all srcset="data:,s4">

  <source id=s5 media=all srcset="data:,s5">

  <source       media=all srcset="data:,s6">

</picture>

<script>

const picture = document.querySelector("picture");

const img1 = document.getElementById("img1");

const img2 = document.getElementById("img2");

const source1 = document.getElementById("s1");

const source2 = document.getElementById("s2");

const source3 = document.getElementById("s3");

const source4 = document.getElementById("s4");

const source5 = document.getElementById("s5");

promise_test(async () => {

  // Wait for the relevant mutation microtask to run.

  await Promise.resolve();

  assert_equals(img1.currentSrc, "data:,s1", "[img1] First source is correctly chosen");

  assert_equals(img2.currentSrc, "data:,s1", "[img2] First source is correctly chosen");

  // Triggers a relevant mutation for *all* image children under the parent

  // `<picture>` element to update their source.

  source1.remove();

  await Promise.resolve();

  assert_equals(img1.currentSrc, "data:,s2",

      "[img1] Second source is chosen after first is removed");

  assert_equals(img2.currentSrc, "data:,s2",

      "[img2] Second source is chosen after first is removed");

  source2.remove();

  await Promise.resolve();

  assert_equals(img1.currentSrc, "data:,s3",

      "[img1] Third is chosen after first is removed");

  assert_equals(img2.currentSrc, "data:,s3",

      "[img2] Third is chosen after first is removed");

  document.body.moveBefore(source3, null);

  await Promise.resolve();

  assert_equals(img1.currentSrc, "data:,img1",

      "[img1] Img src attribute is chosen after third source is moved");

  assert_equals(img2.currentSrc, "data:,img2",

      "[img2] Img src attribute is chosen after third source is moved");

  source4.remove();

  await Promise.resolve();

  assert_equals(img1.currentSrc, "data:,img1",

      "[img1] Img src attribute is unchanged after source is removed from after the img");

  assert_equals(img2.currentSrc, "data:,img2",

      "[img2] Img src attribute is unchanged after source is removed from after the img");

  document.body.moveBefore(source5, null);

  await Promise.resolve();

  assert_equals(img1.currentSrc, "data:,img1",

      "[img1] Img src attribute is unchanged after source is moved from after the img");

  assert_equals(img2.currentSrc, "data:,img2",

      "[img2] Img src attribute is unchanged after source is moved from after the img");

  picture.prepend(source2);

  await Promise.resolve();

  assert_equals(img1.currentSrc, "data:,s2",

      "[img1] Second source is chosen after inserted before the img element");

  assert_equals(img2.currentSrc, "data:,s2",

      "[img2] Second source is chosen after inserted before the img element");

  picture.prepend(source1);

  await Promise.resolve();

  assert_equals(img1.currentSrc, "data:,s1",

      "[img1] First source is chosen after inserted before the img element");

  assert_equals(img2.currentSrc, "data:,s1",

      "[img2] First source is chosen after inserted before the img element");

}, "Neither the removing, moving, nor insertion steps for the source element " +

   "track the previous 'next sibling' pointer when triggering relevant " +

   "mutations for remaining child image elements of its old parent");

</script>