1 files changed, 61 insertions, 0 deletions
diff --git a/testing/web-platform/tests/css/css-layout-api/auto-block-size/flex.https.html b/testing/web-platform/tests/css/css-layout-api/auto-block-size/flex.https.html
new file mode 100644
index 0000000000..96fe3c79a9
--- /dev/null
+++ b/testing/web-platform/tests/css/css-layout-api/auto-block-size/flex.https.html
@@ -0,0 +1,61 @@
+<!DOCTYPE html>
+<html class=reftest-wait>
+<link rel="help" href="https://drafts.css-houdini.org/css-layout-api/#interaction-sizing">
+<link rel="match" href="flex-ref.html">
+<meta name="assert" content="This test checks that the flex layout respects the auto-block-size." />
+
+<style>
+.flex {
+  width: 300px;
+  display: flex;
+  border: solid 2px;
+}
+
+.custom {
+  background: red;
+  box-sizing: border-box;
+  border: solid 2px;
+  height: 100px;
+  writing-mode: vertical-rl;
+}
+
+@supports (display: layout(block-size-100)) {
+  .custom-100 {
+    display: layout(block-size-100);
+    background: green;
+  }
+  .custom-50 {
+    display: layout(block-size-50);
+    background: green;
+    flex: 1;
+  }
+}
+</style>
+<script src="/common/reftest-wait.js"></script>
+<script src="/common/worklet-reftest.js"></script>
+
+<!-- Tests that floats using an auto block size get positioned correctly. -->
+<div class="flex">
+  <div class="custom custom-100"></div>
+  <div class="custom custom-50"></div>
+</div>
+
+<script id="code" type="text/worklet">
+registerLayout('block-size-100', class {
+  async intrinsicSizes() {}
+  async layout() {
+    return {autoBlockSize: 100};
+  }
+});
+registerLayout('block-size-50', class {
+  async intrinsicSizes() {}
+  async layout() {
+    return {autoBlockSize: 50};
+  }
+});
+</script>
+
+<script>
+importWorkletAndTerminateTestAfterAsyncPaint(CSS.layoutWorklet, document.getElementById('code').textContent);
+</script>
+</html>