rafa/test/unit/core/Stream-toProperty.js

Rafa.js is a Javascript framework for building concurrent applications.

module.exports = (assert, Rafa) => {
  suite("toProperty", () => {
    test("creates new property", () => {
      var stream = Rafa.stream();
      var property = stream.toProperty();
      stream.write(1);
      assert.equal(property.get(), 1);
      stream.write(2);
      assert.equal(property.get(), 2);
    });

    test("applies back pressure to child streams", () => {
      var stream = Rafa.stream();
      var channel = Rafa.channel();
      var nested;
      var values = [];
      
      stream.toProperty()
        .flatMap(v => { values.push(v); return nested = Rafa.stream(); })
        .each(v => values.push(v));

      stream.enumerate(channel);

      // write #1 to channel should flow through to flatMap
      channel.write(1);
      assert.equal(values.length, 1);
      assert.equal(values[0], 1);

      // write #2 to channel should be dropped
      assert.equal(channel.write(2), 0);
      assert.equal(values.length, 1);
      assert.equal(values[0], 1);

      // writing a done message from flatMap
      // to release the back pressure
      nested.write(3, true);
      assert.equal(values.length, 2);
      assert.equal(values[1], 3);

      // channel should be open
      channel.write(4);
      assert.equal(values.length, 3);
      assert.equal(values[2], 4);
    });
  });
};