1 files changed, 55 insertions, 0 deletions
diff --git a/testing/web-platform/tests/compression/compression-with-detach.tentative.window.js b/testing/web-platform/tests/compression/compression-with-detach.tentative.window.js
new file mode 100644
index 0000000000..786bba21c8
--- /dev/null
+++ b/testing/web-platform/tests/compression/compression-with-detach.tentative.window.js
@@ -0,0 +1,55 @@
+// META: global=window,worker
+// META: script=resources/concatenate-stream.js
+
+'use strict';
+
+const kInputLength = 500000;
+
+function createLargeRandomInput() {
+  const buffer = new ArrayBuffer(kInputLength);
+  // The getRandomValues API will only let us get 65536 bytes at a time, so call
+  // it multiple times.
+  const kChunkSize = 65536;
+  for (let offset = 0; offset < kInputLength; offset += kChunkSize) {
+    const length =
+        offset + kChunkSize > kInputLength ? kInputLength - offset : kChunkSize;
+    const view = new Uint8Array(buffer, offset, length);
+    crypto.getRandomValues(view);
+  }
+  return new Uint8Array(buffer);
+}
+
+function decompress(view) {
+  const ds = new DecompressionStream('deflate');
+  const writer = ds.writable.getWriter();
+  writer.write(view);
+  writer.close();
+  return concatenateStream(ds.readable);
+}
+
+promise_test(async () => {
+  const input = createLargeRandomInput();
+  const inputCopy = input.slice(0, input.byteLength);
+  const cs = new CompressionStream('deflate');
+  const writer = cs.writable.getWriter();
+  writer.write(input);
+  writer.close();
+  // Object.prototype.then will be looked up synchronously when the promise
+  // returned by read() is resolved.
+  Object.defineProperty(Object.prototype, 'then', {
+    get() {
+      // Cause input to become detached and unreferenced.
+      try {
+        postMessage(undefined, 'nowhere', [input.buffer]);
+      } catch (e) {
+        // It's already detached.
+      }
+    }
+  });
+  const output = await concatenateStream(cs.readable);
+  // Perform the comparison as strings since this is reasonably fast even when
+  // JITted JavaScript is running under an emulator.
+  assert_equals(
+      inputCopy.toString(), (await decompress(output)).toString(),
+      'decompressing the output should return the input');
+}, 'data should be correctly compressed even if input is detached partway');