parametrize tests

[tal66]

hi, this closes #72.

[Kai-Striega]

Looks good to me! I've run the test suite to see if there are any problems.

There's one more improvement I think we can make. Notice how the values for Decimal and Float types are the same? i think we can parameterise across the dtype aswell. See the below test for an example:

numpy-financial/tests/test_financial.py

Lines 102 to 119 in cd724f0

	@pytest.mark.parametrize('number_type', [Decimal, float])
	@pytest.mark.parametrize('when', [0, 1, 'end', 'begin'])
	def test_rate_with_infeasible_solution(self, number_type, when):
	"""
	Test when no feasible rate can be found.
	Rate will return NaN, if the Newton Raphson method cannot find a
	feasible rate within the required tolerance or number of iterations.
	This can occur if both `pmt` and `pv` have the same sign, as it is
	impossible to repay a loan by making further withdrawls.
	"""
	result = npf.rate(number_type(12.0),
	number_type(400.0),
	number_type(10000.0),
	number_type(5000.0),
	when=when)
	is_nan = Decimal.is_nan if number_type == Decimal else numpy.isnan
	assert is_nan(result)

Thank you for taking the time to contribute

[Kai-Striega]

@tal66 this looks good now and tests are green. I don't think there's much more that needs to be done. Are you happy for me to merge it?

[tal66]

sure

[Kai-Striega]

Merged :) Thanks again for taking the time to contribute!