node/test/parallel/test-stream-writable-change-default-encoding.js

'use strict';
require('../common');
const assert = require('assert');

const stream = require('stream');
const util = require('util');

function MyWritable(fn, options) {
  stream.Writable.call(this, options);
  this.fn = fn;
}

util.inherits(MyWritable, stream.Writable);

MyWritable.prototype._write = function(chunk, encoding, callback) {
  this.fn(Buffer.isBuffer(chunk), typeof chunk, encoding);
  callback();
};

(function defaultCondingIsUtf8() {
  const m = new MyWritable(function(isBuffer, type, enc) {
    assert.strictEqual(enc, 'utf8');
  }, { decodeStrings: false });
  m.write('foo');
  m.end();
}());

(function changeDefaultEncodingToAscii() {
  const m = new MyWritable(function(isBuffer, type, enc) {
    assert.strictEqual(enc, 'ascii');
  }, { decodeStrings: false });
  m.setDefaultEncoding('ascii');
  m.write('bar');
  m.end();
}());

assert.throws(function changeDefaultEncodingToInvalidValue() {
  const m = new MyWritable(function(isBuffer, type, enc) {
  }, { decodeStrings: false });
  m.setDefaultEncoding({});
  m.write('bar');
  m.end();
}, TypeError);

(function checkVairableCaseEncoding() {
  const m = new MyWritable(function(isBuffer, type, enc) {
    assert.strictEqual(enc, 'ascii');
  }, { decodeStrings: false });
  m.setDefaultEncoding('AsCii');
  m.write('bar');
  m.end();
}());