def test_check_known_pace(self):
"""Check pace for some speeds."""
# speed, distance for pace, pace
known_values = [
['1 m/s', '1 km', '1000s'],
['1 meters/s', '1 km', '1000s'],
['1 mi/hr', '1 mi', '1 hr']
]
for speed, distance, pace in known_values:
s, d, t = Speed(speed), Distance(distance), Time(pace)
self.assertEqual(s.pace(d)['s'], t['s']) # the seconds should be correct
def test_simple_speeds(self):
"""Create a few speeds and check the value."""
s = Speed('1 mi/hr')
self.assertEqual(s['mi/hr'], 1)
s['miles/hr'] = 2.5
self.assertEqual(s['mi/hr'], 2.5)
self.assertEqual(s['m/s'], 2.5*Distance('1mi')['m']/Time('1hr')['s'])
def test_str(self):
"""str() prints a reasonable form for the quantity."""
# dimensionless case
p = PhysicalQuantity(Dimension(), "2.1e2")
self.assertEqual(str(p), "210")
# For quantities that are NOT dimensionless we use the "basic unit" (whatever has a unit conversion
# factor, so it's SI in our case) with the shortest string representation.
# Also, in both the numerator and denominator the order followed is M L T Q Theta
p = Speed("60 km/min")
self.assertEqual(str(p), "1000 m/s")
p = PhysicalQuantity(Dimension(Q = 1), "4 coulomb")
self.assertEqual(str(p), "4 C")
p = Temperature("4 kelvin")
self.assertEqual(str(p), "4 K")
p = Speed("30m/s")/Time("2s")/PhysicalQuantity(Dimension(M = 1), "3kg")
self.assertEqual(str(p), "5 m/kgs^2")
def test_get_available_units(self):
"""Test that I can get the available units."""
self.assertEqual(set(PhysicalQuantity(Dimension()).get_available_units()), set(["1"]))
# test only whether it's a subset, so it doesn't fail as I add more units
self.assertTrue(set(["kg", "kilogram", "g", "gram"])
<= set(PhysicalQuantity(Dimension(M = 1)).get_available_units()))
self.assertTrue(set(["m/s", "meters/second", "miles/hour", "mi/hr"])
<= set(Speed().get_available_units()))
def test_multiplication_and_division_of_combined_units(self):
d = Distance("10m")
t = Time("5s")
s1 = d/t # division
s2 = Speed("2m/s")
self.assertEqual(s1.dimension, s2.dimension)
self.assertEqual(s1, s2)
d2 = s2*t # multiplication
self.assertEqual(d2, d)
def test_power(self):
"""I can raise quantities to integer or fractional powers."""
L = Distance("3m")
A = L**2
self.assertEqual(A, L*L)
V = L**3
self.assertEqual(V, L*L*L)
L2 = A**0.5
self.assertEqual(L2, L)
# type guessing works
m = Mass("7 kg")
v = Speed("11 m/s")
E = 1/2*m*v**2
self.assertEqual(E['J'], 1/2*7*11*11)
def test_type_coercion_on_addition_and_subtraction(self):
"""A PhysicalQuantity, when added/subtracted to/from a Time becomes a Time."""
t1 = Time("5s")
t2 = PhysicalQuantity(Dimension(T = 1), "1 min")
self.assertTrue(type(t1) != type(t2)) # sanity check before the real check
# coercion on the left & right
self.assertEqual(type(t1 + t2), type(t1))
self.assertEqual(type(t2 + t1), type(t1))
self.assertEqual(type(t1 - t2), type(t1))
self.assertEqual(type(t2 - t1), type(t1))
# A more complex example
s = Speed("3 m/s")
d = Distance("4 m")
t = Time("4 s")
self.assertEqual(type(s + d/t), Speed)
self.assertEqual(type(d/t + s), Speed)
def test_repr(self):
"""repr() should give something that can be used to recreate the object."""
p1 = PhysicalQuantity(Dimension(L = 1), "2m")
p2 = eval(repr(p1))
self.assertEqual(p1, p2)
# special case: dimensionless quantities
p1 = PhysicalQuantity(Dimension(), "2")
p2 = eval(repr(p1))
self.assertEqual(p1, p2)
# derived quantities should also work
t1 = Time("3 min")
t2 = eval(repr(t1))
self.assertEqual(t1, t2)
# a more complicated case
p1 = Speed("30m/s")/Time("2s")/PhysicalQuantity(Dimension(M = 1), "3kg")
p2 = eval(repr(p1))
self.assertEqual(p1, p2)
def test_type_guessing_in_general(self):
"""The library should find the proper type depending on dimensions."""
d = Distance("10m")
t = Time("5s")
self.assertEqual(type(d/t), Speed)
v = Speed("10mi/hr")
self.assertEqual(type(v*t), Distance)
# charge density
rho = PhysicalQuantity(Dimension(L = -3, Q = 1), "4C/m^3")
q = rho*d*d*d
self.assertEqual(type(q), Charge)
self.assertEqual(q['C'], 4000)
# Note: this doesn't work for a quantity explicitly defined as a PhysicalQuantity
T1 = Temperature("3 K")
T2 = PhysicalQuantity(Dimension(Theta = 1), "3 K")
self.assertEqual(T1, T2)
self.assertEqual(type(T1), Temperature)
self.assertEqual(type(T2), PhysicalQuantity)
# But a multiplication or division by a dimensionless quantity should fix that
T3 = T2/PhysicalQuantity(Dimension(), "1")
self.assertEqual(type(T3), Temperature)