1 files changed, 38 insertions, 0 deletions
diff --git a/testing/web-platform/tests/encoding/streams/decode-ignore-bom.any.js b/testing/web-platform/tests/encoding/streams/decode-ignore-bom.any.js
new file mode 100644
index 0000000000..92f89c8015
--- /dev/null
+++ b/testing/web-platform/tests/encoding/streams/decode-ignore-bom.any.js
@@ -0,0 +1,38 @@
+// META: global=window,worker
+// META: script=resources/readable-stream-from-array.js
+// META: script=resources/readable-stream-to-array.js
+
+const cases = [
+    {encoding: 'utf-8', bytes: [0xEF, 0xBB, 0xBF, 0x61, 0x62, 0x63]},
+    {encoding: 'utf-16le', bytes: [0xFF, 0xFE, 0x61, 0x00, 0x62, 0x00, 0x63, 0x00]},
+    {encoding: 'utf-16be', bytes: [0xFE, 0xFF, 0x00, 0x61, 0x00, 0x62, 0x00, 0x63]}
+];
+const BOM = '\uFEFF';
+
+// |inputChunks| is an array of chunks, each represented by an array of
+// integers. |ignoreBOM| is true or false. The result value is the output of the
+// pipe, concatenated into a single string.
+async function pipeAndAssemble(inputChunks, encoding, ignoreBOM) {
+  const chunksAsUint8 = inputChunks.map(values => new Uint8Array(values));
+  const readable = readableStreamFromArray(chunksAsUint8);
+  const outputArray = await readableStreamToArray(readable.pipeThrough(
+      new TextDecoderStream(encoding, {ignoreBOM})));
+  return outputArray.join('');
+}
+
+for (const testCase of cases) {
+  for (let splitPoint = 0; splitPoint < 4; ++splitPoint) {
+    promise_test(async () => {
+      const inputChunks = [testCase.bytes.slice(0, splitPoint),
+                           testCase.bytes.slice(splitPoint)];
+      const withIgnoreBOM =
+            await pipeAndAssemble(inputChunks, testCase.encoding, true);
+      assert_equals(withIgnoreBOM, BOM + 'abc', 'BOM should be preserved');
+
+      const withoutIgnoreBOM =
+            await pipeAndAssemble(inputChunks, testCase.encoding, false);
+      assert_equals(withoutIgnoreBOM, 'abc', 'BOM should be stripped')
+    }, `ignoreBOM should work for encoding ${testCase.encoding}, split at ` +
+       `character ${splitPoint}`);
+  }
+}