def test_Particle_speed_should_remain_constant():
almost_eq = approximately_eq(13)
assert_speed_unchanged = assert_evolution(lambda:abs(p.vel), almost_eq)
p = Particle(30, 40, 50, 60, 70)
for dt in xrange(10,30,1):
p.move(dt/1000.0)
assert_speed_unchanged()
def test_assert_evolution_should_fail_with_non_constant_expression_and_eq():
assert_invariant = assert_evolution(lambda:x, eq)
x = 1
assert_invariant()
assert_invariant()
x = 2
with raises(AssertionError):
assert_invariant()
def test_assert_evolution_should_work_with_increasing_expression_and_gt():
assert_increasing = assert_evolution(lambda:x, gt)
for x in range(20):
assert_increasing()
x -= 2
with raises(AssertionError):
assert_increasing()
def test_assert_evolution_should_work_with_increasing_expression_and_gt():
assert_increasing = assert_evolution(lambda: x, gt)
for x in range(20):
assert_increasing()
x -= 2
with raises(AssertionError):
assert_increasing()
def test_assert_evolution_should_fail_with_non_constant_expression_and_eq():
assert_invariant = assert_evolution(lambda: x, eq)
x = 1
assert_invariant()
assert_invariant()
x = 2
with raises(AssertionError):
assert_invariant()
def test_assert_evolution_should_work_with_constant_expression_and_eq():
assert_invariant = assert_evolution(lambda:x, eq)
for x in 'aaaaa':
assert_invariant()
def test_assert_evolution_should_fail_with_constant_expression_and_gt():
assert_increasing = assert_evolution(lambda:x, gt)
x = 1
assert_increasing()
with raises(AssertionError):
assert_increasing()
def test_assert_evolution_should_work_with_constant_expression_and_eq():
assert_invariant = assert_evolution(lambda: x, eq)
for x in 'aaaaa':
assert_invariant()
def test_assert_evolution_should_fail_with_constant_expression_and_gt():
assert_increasing = assert_evolution(lambda: x, gt)
x = 1
assert_increasing()
with raises(AssertionError):
assert_increasing()