1 files changed, 50 insertions, 0 deletions
diff --git a/testing/web-platform/tests/encoding/streams/decode-split-character.any.js b/testing/web-platform/tests/encoding/streams/decode-split-character.any.js
new file mode 100644
index 0000000000..d589694fce
--- /dev/null
+++ b/testing/web-platform/tests/encoding/streams/decode-split-character.any.js
@@ -0,0 +1,50 @@
+// META: global=window,worker
+// META: script=resources/readable-stream-from-array.js
+// META: script=resources/readable-stream-to-array.js
+
+'use strict';
+
+const inputBytes = [73, 32, 240, 159, 146, 153, 32, 115, 116, 114, 101,
+                    97, 109, 115];
+for (const splitPoint of [2, 3, 4, 5]) {
+  promise_test(async () => {
+    const input = readableStreamFromArray(
+        [new Uint8Array(inputBytes.slice(0, splitPoint)),
+         new Uint8Array(inputBytes.slice(splitPoint))]);
+    const expectedOutput = ['I ', '\u{1F499} streams'];
+    const output = input.pipeThrough(new TextDecoderStream());
+    const array = await readableStreamToArray(output);
+    assert_array_equals(array, expectedOutput,
+                        'the split code point should be in the second chunk ' +
+                        'of the output');
+  }, 'a code point split between chunks should not be emitted until all ' +
+      'bytes are available; split point = ' + splitPoint);
+}
+
+promise_test(async () => {
+  const splitPoint = 6;
+  const input = readableStreamFromArray(
+      [new Uint8Array(inputBytes.slice(0, splitPoint)),
+       new Uint8Array(inputBytes.slice(splitPoint))]);
+  const output = input.pipeThrough(new TextDecoderStream());
+  const array = await readableStreamToArray(output);
+  assert_array_equals(array, ['I \u{1F499}', ' streams'],
+                      'the multibyte character should be in the first chunk ' +
+                      'of the output');
+}, 'a code point should be emitted as soon as all bytes are available');
+
+for (let splitPoint = 1; splitPoint < 7; ++splitPoint) {
+  promise_test(async () => {
+    const input = readableStreamFromArray(
+      [new Uint8Array(inputBytes.slice(0, splitPoint)),
+       new Uint8Array([]),
+       new Uint8Array(inputBytes.slice(splitPoint))]);
+    const concatenatedOutput = 'I \u{1F499} streams';
+    const output = input.pipeThrough(new TextDecoderStream());
+    const array = await readableStreamToArray(output);
+    assert_equals(array.length, 2, 'two chunks should be output');
+    assert_equals(array[0].concat(array[1]), concatenatedOutput,
+                  'output should be unchanged by the empty chunk');
+  }, 'an empty chunk inside a code point split between chunks should not ' +
+     'change the output; split point = ' + splitPoint);
+}