function expectStrokeEquals(stroke, expected) {
  expect(stroke).to.be.a(Stroke);

  const expectedColor = expected.getColor();
  expect(stroke.getColor()).to.eql(expectedColor);

  const expectedWidth = expected.getWidth();
  expect(stroke.getWidth()).to.eql(expectedWidth);
}
@param {Stroke} stroke The stroke to test.
@param {Stroke} expected The expected stroke.