def test_mass_subtracting(self):
"""Test subtracting masses."""
m1 = Mass("10 kg")
m2 = Mass("300 g")
m3 = m1 - m2
self.assertEqual(m1.dimension, m3.dimension) # type is the same
self.assertAlmostEqual(m3['g'], 9700)
def test_mass_adding(self):
"""Test adding masses."""
m1 = Mass("10 kg")
m2 = Mass("300 g")
m3 = m1 + m2
self.assertEqual(m1.dimension, m3.dimension) # type is the same
self.assertEqual(m3['kg'], 10.3)
def test_creating_from_other_mass(self):
"""I can create a mass from another."""
m1 = Mass("10 kg")
m2 = Mass(m1)
self.assertEqual(m1, m2)
m2['kg'] = 2
self.assertEqual(m2['kg'], 2)
self.assertEqual(m1['kg'], 10) # check that we didn't modify the original one
def test_create_simple_masses(self):
"""Simple masses."""
# Check consistency
for unit,kilograms in self.kilograms_in.iteritems():
m = Mass('1' + unit) # create "1x" where x is the unit
self.assertEqual(m['kg'], kilograms) # the kilograms should be correct
# Check creating from other distances
m1 = Mass("1 kg")
m2 = Mass(m1)
self.assertEqual(m1['kg'], m2['kg'])
# Check creating from another quantity with same dimensions
m1 = PhysicalQuantity(Dimension(M = 1), "1 kg")
m2 = Mass(m1)
self.assertEqual(m1['kg'], m2['kg'])
# Check creating from another quantity with different dimensions
t = PhysicalQuantity(Dimension(T = 1), "1 s")
self.assertRaises(IncompatibleUnitsError, Mass, t)
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_for_mass_equality(self):
"""Test that masses are only compared by length."""
m1 = Mass("1g")
m2 = Mass("0.001kg")
self.assertEqual(m1['kg'], m2['kg']) # sanity check before the real test
self.assertEqual(m1, m2)
def test_consistency(self):
"""In its own units, the value should be 1."""
for unit in self.kilograms_in.keys():
m = Mass('1' + unit) # create "1x" where x is the unit
self.assertEqual(m[unit], 1)