1 files changed, 127 insertions, 0 deletions
diff --git a/test/bun.js/string-decoder.test.js b/test/bun.js/string-decoder.test.js
new file mode 100644
index 000000000..8f3ad7695
--- /dev/null
+++ b/test/bun.js/string-decoder.test.js
@@ -0,0 +1,127 @@
+import { expect, it } from "bun:test";
+import { StringDecoder } from "string_decoder";
+
+it("StringDecoder-utf8", () => {
+  test('utf-8', Buffer.from('$', 'utf-8'), '$');
+  test('utf-8', Buffer.from('¢', 'utf-8'), '¢');
+  test('utf-8', Buffer.from('€', 'utf-8'), '€');
+  test('utf-8', Buffer.from('𤭢', 'utf-8'), '𤭢');
+  // A mixed ascii and non-ascii string
+  // Test stolen from deps/v8/test/cctest/test-strings.cc
+  // U+02E4 -> CB A4
+  // U+0064 -> 64
+  // U+12E4 -> E1 8B A4
+  // U+0030 -> 30
+  // U+3045 -> E3 81 85
+  test(
+    'utf-8',
+    Buffer.from([0xCB, 0xA4, 0x64, 0xE1, 0x8B, 0xA4, 0x30, 0xE3, 0x81, 0x85]),
+    '\u02e4\u0064\u12e4\u0030\u3045'
+  );
+});
+
+it("StringDecoder-ucs-2", () => {
+  test('ucs2', Buffer.from('ababc', 'ucs2'), 'ababc');
+});
+
+it("StringDecoder-utf16le", () => {
+  test('utf16le', Buffer.from('3DD84DDC', 'hex'), '\ud83d\udc4d');
+});
+
+it("StringDecoder-utf8-additional", () => {
+  let decoder = new StringDecoder('utf8');
+  expect(decoder.write(Buffer.from('E18B', 'hex'))).toBe('');
+  expect(decoder.end()).toBe('\ufffd');
+
+  decoder = new StringDecoder('utf8');
+  expect(decoder.write(Buffer.from('\ufffd'))).toBe('\ufffd');
+  expect(decoder.end()).toBe('');
+
+  decoder = new StringDecoder('utf8');
+  expect(decoder.write(Buffer.from('\ufffd\ufffd\ufffd'))).toBe('\ufffd\ufffd\ufffd');
+  expect(decoder.end()).toBe('');
+
+  decoder = new StringDecoder('utf8');
+  expect(decoder.write(Buffer.from('EFBFBDE2', 'hex'))).toBe('\ufffd');
+  expect(decoder.end()).toBe('\ufffd');
+
+  decoder = new StringDecoder('utf8');
+  expect(decoder.write(Buffer.from('F1', 'hex'))).toBe('');
+  expect(decoder.write(Buffer.from('41F2', 'hex'))).toBe('\ufffdA');
+  expect(decoder.end()).toBe('\ufffd');
+
+  // Additional utf8Text test
+  decoder = new StringDecoder('utf8');
+  expect(decoder.text(Buffer.from([0x41]), 2)).toBe('');
+});
+
+it("StringDecoder-utf16le-additional", () => {
+  // Additional UTF-16LE surrogate pair tests
+  let decoder = new StringDecoder('utf16le');
+  expect(decoder.write(Buffer.from('3DD8', 'hex'))).toBe('');
+  expect(decoder.write(Buffer.from('4D', 'hex'))).toBe('');
+  expect(decoder.write(Buffer.from('DC', 'hex'))).toBe('\ud83d\udc4d');
+  expect(decoder.end()).toBe('');
+
+  decoder = new StringDecoder('utf16le');
+  expect(decoder.write(Buffer.from('3DD8', 'hex'))).toBe('');
+  expect(decoder.end()).toBe('\ud83d');
+
+  decoder = new StringDecoder('utf16le');
+  expect(decoder.write(Buffer.from('3DD8', 'hex'))).toBe('');
+  expect(decoder.write(Buffer.from('4D', 'hex'))).toBe('');
+  expect(decoder.end()).toBe('\ud83d');
+
+  decoder = new StringDecoder('utf16le');
+  expect(decoder.write(Buffer.from('3DD84D', 'hex'))).toBe('\ud83d');
+  expect(decoder.end()).toBe('');
+});
+
+// Test verifies that StringDecoder will correctly decode the given input
+// buffer with the given encoding to the expected output. It will attempt all
+// possible ways to write() the input buffer, see writeSequences(). The
+// singleSequence allows for easy debugging of a specific sequence which is
+// useful in case of test failures.
+function test(encoding, input, expected, singleSequence) {
+  let sequences;
+  if (!singleSequence) {
+    sequences = writeSequences(input.length);
+  } else {
+    sequences = [singleSequence];
+  }
+  sequences.forEach((sequence) => {
+    const decoder = new StringDecoder(encoding);
+    let output = '';
+    sequence.forEach((write) => {
+      output += decoder.write(input.slice(write[0], write[1]));
+    });
+    output += decoder.end();
+    expect(output).toBe(expected);
+  });
+}
+
+// writeSequences returns an array of arrays that describes all possible ways a
+// buffer of the given length could be split up and passed to sequential write
+// calls.
+//
+// e.G. writeSequences(3) will return: [
+//   [ [ 0, 3 ] ],
+//   [ [ 0, 2 ], [ 2, 3 ] ],
+//   [ [ 0, 1 ], [ 1, 3 ] ],
+//   [ [ 0, 1 ], [ 1, 2 ], [ 2, 3 ] ]
+// ]
+function writeSequences(length, start, sequence) {
+  if (start === undefined) {
+    start = 0;
+    sequence = [];
+  } else if (start === length) {
+    return [sequence];
+  }
+  let sequences = [];
+  for (let end = length; end > start; end--) {
+    const subSequence = sequence.concat([[start, end]]);
+    const subSequences = writeSequences(length, end, subSequence, sequences);
+    sequences = sequences.concat(subSequences);
+  }
+  return sequences;
+}