1 files changed, 28 insertions, 0 deletions
diff --git a/testing/web-platform/tests/html/semantics/document-metadata/the-meta-element/color-scheme/support/compute-root-color-scheme.js b/testing/web-platform/tests/html/semantics/document-metadata/the-meta-element/color-scheme/support/compute-root-color-scheme.js
new file mode 100644
index 0000000000..74cbf895ce
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/document-metadata/the-meta-element/color-scheme/support/compute-root-color-scheme.js
@@ -0,0 +1,28 @@
+'use strict';
+
+function assert_root_color_scheme(expected_used_scheme, description) {
+  function get_used_root_color_scheme() {
+    let light = get_system_color("only light", "CanvasText");
+    let dark = get_system_color("only dark", "CanvasText");
+    assert_not_equals(light, dark, "CanvasText system color should be different with light and dark color schemes");
+    let root = getComputedStyle(document.documentElement).color;
+    assert_in_array(root, [light, dark], "Root color scheme should be either light or dark, or the text needs to be extended for newer color-schemes");
+    return root == light ? "light" : "dark";
+  }
+
+  function get_system_color(scheme, color) {
+    let div = document.createElement("div");
+    div.style.color = color;
+    div.style.colorScheme = scheme;
+
+    document.documentElement.appendChild(div);
+    let computed = getComputedStyle(div).color;
+    div.remove();
+    return computed;
+  }
+
+  test(() => {
+    assert_equals(get_used_root_color_scheme(), expected_used_scheme);
+    assert_equals(getComputedStyle(document.documentElement).colorScheme, "normal", "Root element's color-scheme should be 'normal'");
+  }, description);
+}