1 files changed, 60 insertions, 0 deletions
diff --git a/testing/web-platform/tests/encoding/streams/backpressure.any.js b/testing/web-platform/tests/encoding/streams/backpressure.any.js
new file mode 100644
index 0000000000..22f7f0aa2b
--- /dev/null
+++ b/testing/web-platform/tests/encoding/streams/backpressure.any.js
@@ -0,0 +1,60 @@
+// META: global=window,worker
+
+'use strict';
+
+const classes = [
+  {
+    name: 'TextDecoderStream',
+    input: new Uint8Array([65])
+  },
+  {
+    name: 'TextEncoderStream',
+    input: 'A'
+  }
+];
+
+const microtasksRun = () => new Promise(resolve => step_timeout(resolve, 0));
+
+for (const streamClass of classes) {
+  promise_test(async () => {
+    const stream = new self[streamClass.name]();
+    const writer = stream.writable.getWriter();
+    const reader = stream.readable.getReader();
+    const events = [];
+    await microtasksRun();
+    const writePromise = writer.write(streamClass.input);
+    writePromise.then(() => events.push('write'));
+    await microtasksRun();
+    events.push('paused');
+    await reader.read();
+    events.push('read');
+    await writePromise;
+    assert_array_equals(events, ['paused', 'read', 'write'],
+                        'write should happen after read');
+  }, 'write() should not complete until read relieves backpressure for ' +
+     `${streamClass.name}`);
+
+  promise_test(async () => {
+    const stream = new self[streamClass.name]();
+    const writer = stream.writable.getWriter();
+    const reader = stream.readable.getReader();
+    const events = [];
+    await microtasksRun();
+    const readPromise1 = reader.read();
+    readPromise1.then(() => events.push('read1'));
+    const writePromise1 = writer.write(streamClass.input);
+    const writePromise2 = writer.write(streamClass.input);
+    writePromise1.then(() => events.push('write1'));
+    writePromise2.then(() => events.push('write2'));
+    await microtasksRun();
+    events.push('paused');
+    const readPromise2 = reader.read();
+    readPromise2.then(() => events.push('read2'));
+    await Promise.all([writePromise1, writePromise2,
+                       readPromise1, readPromise2]);
+    assert_array_equals(events, ['read1', 'write1', 'paused', 'read2',
+                                 'write2'],
+                        'writes should not happen before read2');
+  }, 'additional writes should wait for backpressure to be relieved for ' +
+     `class ${streamClass.name}`);
+}