@Test
public void resolvesFlatAngle() {

    final double error = 1.e-6;
    final MkField<Object> field = new MkField<>(new Object(), new Object());
    MatcherAssert.assertThat(
        new Flat<>().resolve(field.product()).doubleValue(),
        Matchers.closeTo(Math.PI, error)
    );
    MatcherAssert.assertThat(
        new IsFlat<>(new Flat<>()).resolve(field), Matchers.is(true)
    );
    MatcherAssert.assertThat(
        new IsRight<>(new Flat<>()).resolve(field), Matchers.is(false)
    );
}