def test_translate_zero(self):
"test that tangent equals itself after translation of (0, 0)"
circ1 = Circle()
circ2 = Circle(Vec2D(4, 0))
tan = Tangent(Vec2D(0, 1), circ1, 1, Vec2D(4, 1), circ2, -1)
translated = tan + Vec2D()
self.assertTrue(tan.is_equal(translated))
self.assertTrue(translated.is_equal(tan))
def test_translate_general(self):
"test translation by non-zero vector"
circ1 = Circle()
circ2 = Circle(Vec2D(4, 0))
translation = Vec2D(1, 0)
original = Tangent(Vec2D(0, 1), circ1, 1, Vec2D(4, 1), circ2, -1)
translated = original + translation
v_circ1 = Circle(Vec2D(1, 0))
v_circ2 = Circle(Vec2D(5, 0))
verifier = Tangent(Vec2D(1, 1), v_circ1, 1, Vec2D(5, 1), v_circ2, -1)
self.assertTrue(verifier.is_equal(translated))
self.assertTrue(translated.is_equal(verifier))