def test_subtract_true():
a = Point(1, 2)
b = Point(3, 4)
c = Point(2, 2)
d = Point(-2, -2)
assert b.subtract(a).equals(c) == True
assert a.subtract(b).equals(d) == True
def test_intersection():
line1 = Line(Point(0, 0), Point(2, 0))
line2 = Line(Point(1, 1), Point(1, 0))
assert line1.intersects(line2) == True
assert line2.intersects(line1) == True
def test_collinear_non_intersection():
line1 = Line(Point(0, 1), Point(2, 1))
line2 = Line(Point(3, 1), Point(4, 1))
assert line1.intersects(line2) == False
assert line2.intersects(line1) == False
def test_perpendicular_intersection_two():
line1 = Line(Point(0, 2), Point(2, 2))
line2 = Line(Point(2, 0), Point(2, 2))
assert line1.intersects(line2) == True
assert line2.intersects(line1) == True
def test_parallel():
line1 = Line(Point(0, 1), Point(2, 1))
line2 = Line(Point(0, 2), Point(2, 2))
assert line1.intersects(line2) == False
assert line2.intersects(line1) == False
def test_cross_product():
a = Point(1, 2)
b = Point(3, 4)
assert a.cross_product(b) == -2
assert b.cross_product(a) == 2
def test_subtract_zero():
a = Point(1, 2)
b = Point(0, 0)
assert a.subtract(a).equals(b) == True
def test_subtract_false():
a = Point(1, 2)
b = Point(3, 4)
assert a.subtract(b).equals(b) == False
def test_equals_false():
a = Point(1, 2)
b = Point(2, 1)
assert a.equals(b) == False
assert b.equals(a) == False
def test_equals_true():
a = Point(1, 2)
b = Point(1, 2)
assert a.equals(b) == True
assert b.equals(a) == True