node/test/simple/test-utf8-decoder.js

require('../common');
var Utf8Decoder = require('utf8decoder').Utf8Decoder,
    Buffer = require('buffer').Buffer,
    decoder = new Utf8Decoder(),
    buffer,
    onStringCalled = 0;

decoder.onString = function(str) {
  onStringCalled++;
  assert.deepEqual(str, buffer.toString());
};

buffer = new Buffer('$');
decoder.write(buffer);
assert.equal(onStringCalled, 1);

buffer = new Buffer('¢');
decoder.write(buffer.slice(0, 1));
decoder.write(buffer.slice(1, 2));
assert.equal(onStringCalled, 2);

buffer = new Buffer('€');
decoder.write(buffer.slice(0, 1));
decoder.write(buffer.slice(1, 2));
decoder.write(buffer.slice(2, 3));
assert.equal(onStringCalled, 3);

buffer = new Buffer([0xF0, 0xA4, 0xAD, 0xA2]);
decoder.write(buffer.slice(0, 1));
decoder.write(buffer.slice(1, 2));
decoder.write(buffer.slice(2, 3));
decoder.write(buffer.slice(3, 4));
assert.equal(onStringCalled, 4);

// 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
expected = "\u02e4\u0064\u12e4\u0030\u3045";
buffer = new Buffer([0xCB, 0xA4, 0x64, 0xE1, 0x8B, 0xA4, 0x30, 0xE3, 0x81, 0x85]);
charLengths = [0, 0, 1, 2, 2, 2, 3, 4, 4, 4, 5, 5];

// Split the buffer into 3 segments
//  |----|------|-------|
//  0    i      j       buffer.length
// Scan through every possible 3 segment combination
// and make sure that the string is always parsed.
print('scanning ');
for (var j = 2; j < buffer.length; j++) {
  for (var i = 1; i < j; i++) {
    var decoder = new Utf8Decoder();
    var sum = "";
    decoder.onString = function (s) { sum += s; };

    decoder.write(buffer.slice(0, i));

    // just check that we've received the right amount
    // after the first write
    assert.equal(charLengths[i], sum.length);

    decoder.write(buffer.slice(i, j));
    decoder.write(buffer.slice(j, buffer.length));
    assert.equal(expected, sum);
    print(".");
  }
}
puts(" crayon!");