<!DOCTYPE html> <html class="reftest-wait foo"> <title>View transitions: ensure :only-child is supported on view-transition-image-pair</title> <link rel="help" href="https://github.com/WICG/view-transitions"> <link rel="author" href="mailto:khushalsagar@chromium.org"> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> <style> ::view-transition { background-color: black; } html:only-child { background-color: black; } :root:only-child { background-color: black; } :only-child { background-color: black; } .foo:only-child { background-color: black; } ::view-transition-image-pair(root):only-child { background-color: red; } ::view-transition-image-pair(*):only-child { color: red; } </style> <script> promise_test(() => { assert_implements(document.startViewTransition, "Missing document.startViewTransition"); return new Promise(async (resolve, reject) => { let transition = document.startViewTransition(); transition.ready.then(() => { let style = getComputedStyle( document.documentElement, ":view-transition-image-pair(root)"); if (style.backgroundColor == "rgb(255, 0, 0)" && style.color == "rgb(255, 0, 0)") resolve(); else reject(style.backgroundColor + " and " + style.color); }); }); }, ":only-child should always match for ::view-transition-image-pair"); </script>