1 files changed, 63 insertions, 0 deletions
diff --git a/testing/web-platform/tests/compression/compression-including-empty-chunk.tentative.any.js b/testing/web-platform/tests/compression/compression-including-empty-chunk.tentative.any.js
new file mode 100644
index 0000000000..0948029c4b
--- /dev/null
+++ b/testing/web-platform/tests/compression/compression-including-empty-chunk.tentative.any.js
@@ -0,0 +1,63 @@
+// META: global=window,worker
+// META: script=third_party/pako/pako_inflate.min.js
+// META: timeout=long
+
+'use strict';
+
+// This test asserts that compressing '' doesn't affect the compressed data.
+// Example: compressing ['Hello', '', 'Hello'] results in 'HelloHello'
+
+async function compressChunkList(chunkList, format) {
+  const cs = new CompressionStream(format);
+  const writer = cs.writable.getWriter();
+  for (const chunk of chunkList) {
+    const chunkByte = new TextEncoder().encode(chunk);
+    writer.write(chunkByte);
+  }
+  const closePromise = writer.close();
+  const out = [];
+  const reader = cs.readable.getReader();
+  let totalSize = 0;
+  while (true) {
+    const { value, done } = await reader.read();
+    if (done)
+      break;
+    out.push(value);
+    totalSize += value.byteLength;
+  }
+  await closePromise;
+  const concatenated = new Uint8Array(totalSize);
+  let offset = 0;
+  for (const array of out) {
+    concatenated.set(array, offset);
+    offset += array.byteLength;
+  }
+  return concatenated;
+}
+
+const chunkLists = [
+  ['', 'Hello', 'Hello'],
+  ['Hello', '', 'Hello'],
+  ['Hello', 'Hello', '']
+];
+const expectedValue = new TextEncoder().encode('HelloHello');
+
+for (const chunkList of chunkLists) {
+  promise_test(async t => {
+    const compressedData = await compressChunkList(chunkList, 'deflate');
+    // decompress with pako, and check that we got the same result as our original string
+    assert_array_equals(expectedValue, pako.inflate(compressedData), 'value should match');
+  }, `the result of compressing [${chunkList}] with deflate should be 'HelloHello'`);
+
+  promise_test(async t => {
+    const compressedData = await compressChunkList(chunkList, 'gzip');
+    // decompress with pako, and check that we got the same result as our original string
+    assert_array_equals(expectedValue, pako.inflate(compressedData), 'value should match');
+  }, `the result of compressing [${chunkList}] with gzip should be 'HelloHello'`);
+
+  promise_test(async t => {
+    const compressedData = await compressChunkList(chunkList, 'deflate-raw');
+    // decompress with pako, and check that we got the same result as our original string
+    assert_array_equals(expectedValue, pako.inflateRaw(compressedData), 'value should match');
+  }, `the result of compressing [${chunkList}] with deflate-raw should be 'HelloHello'`);
+}