1 files changed, 52 insertions, 0 deletions
diff --git a/testing/web-platform/tests/html/rendering/replaced-elements/attributes-for-embedded-content-and-images/canvas-aspect-ratio.html b/testing/web-platform/tests/html/rendering/replaced-elements/attributes-for-embedded-content-and-images/canvas-aspect-ratio.html
new file mode 100644
index 0000000000..dbe4c7d9f3
--- /dev/null
+++ b/testing/web-platform/tests/html/rendering/replaced-elements/attributes-for-embedded-content-and-images/canvas-aspect-ratio.html
@@ -0,0 +1,52 @@
+<!doctype html>
+<title>Canvas width and height attributes are used as the surface size, and also to infer aspect ratio</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/aspect-ratio.js"></script>
+<style>
+  canvas {
+    width: 100%;
+    max-width: 100px;
+    height: auto;
+  }
+</style>
+<body>
+<canvas id="contained" width="250" height="100" style="contain: size;"></canvas>
+<script>
+function assert_ratio(img, expected) {
+  let epsilon = 0.001;
+  assert_approx_equals(parseInt(getComputedStyle(img).width, 10) / parseInt(getComputedStyle(img).height, 10), expected, epsilon);
+}
+
+function test_computed_style(width, height, expected) {
+  test_computed_style_aspect_ratio("canvas", {width: width, height: height}, expected);
+}
+
+test(function() {
+  canvas = document.getElementById("contained");
+  assert_ratio(canvas, 2.5);
+}, "Canvas width and height attributes are used as the surface size with contain:size");
+
+// Create and append a new canvas and immediately check the ratio.
+test(function() {
+  var canvas = document.createElement("canvas");
+  canvas.setAttribute("width", "250");
+  canvas.setAttribute("height", "100");
+  document.body.appendChild(canvas);
+  // Canvases always use the aspect ratio from their surface size.
+  assert_ratio(canvas, 2.5);
+}, "Canvas width and height attributes are used as the surface size");
+
+test_computed_style("10", "20", "auto 10 / 20");
+test_computed_style("0", "1", "auto 0 / 1");
+test_computed_style("1", "0", "auto 1 / 0");
+test_computed_style("0", "0", "auto 0 / 0");
+test_computed_style("0.5", "1.5", "auto 0 / 1");
+test_computed_style("10%", "20", "auto 10 / 20");
+test_computed_style(null, null, "auto");
+test_computed_style("10", null, "auto");
+test_computed_style(null, "20", "auto");
+test_computed_style("xx", "20", "auto");
+test_computed_style("20", "xx", "auto");
+
+</script>