Implement ignoreBOM option of UTF8Decoder in text_encoding (#3040)

1 files changed, 26 insertions, 0 deletions

diff --git a/js/text_encoding_test.ts b/js/text_encoding_test.ts
index 727424749..aaa9e6b9d 100644
--- a/js/text_encoding_test.ts
+++ b/js/text_encoding_test.ts
@@ -74,6 +74,32 @@ test(function textDecoder2(): void {
   assertEquals(decoder.decode(fixture), "𝓽𝓮𝔁𝓽");
 });
 
+test(function textDecoderIgnoreBOM(): void {
+  // prettier-ignore
+  const fixture = new Uint8Array([
+    0xef, 0xbb, 0xbf,
+    0xf0, 0x9d, 0x93, 0xbd,
+    0xf0, 0x9d, 0x93, 0xae,
+    0xf0, 0x9d, 0x94, 0x81,
+    0xf0, 0x9d, 0x93, 0xbd
+  ]);
+  const decoder = new TextDecoder("utf-8", { ignoreBOM: true });
+  assertEquals(decoder.decode(fixture), "𝓽𝓮𝔁𝓽");
+});
+
+test(function textDecoderNotBOM(): void {
+  // prettier-ignore
+  const fixture = new Uint8Array([
+    0xef, 0xbb, 0x89,
+    0xf0, 0x9d, 0x93, 0xbd,
+    0xf0, 0x9d, 0x93, 0xae,
+    0xf0, 0x9d, 0x94, 0x81,
+    0xf0, 0x9d, 0x93, 0xbd
+  ]);
+  const decoder = new TextDecoder("utf-8", { ignoreBOM: true });
+  assertEquals(decoder.decode(fixture), "ﻉ𝓽𝓮𝔁𝓽");
+});
+
 test(function textDecoderASCII(): void {
   const fixture = new Uint8Array([0x89, 0x95, 0x9f, 0xbf]);
   const decoder = new TextDecoder("ascii");