Parametrization

A common testing activity is passing multiple values to the same test function and asserting the outcome.

Suppose we have an application that allows the user to define custom mathematical formulas, which will be parsed and evaluated at runtime. The formulas are given as strings, and can make use of mathematical functions such as sin, cos, log, and so on. A very simple way to implement this in Python would be to use the eval built-in (https://docs.python.org/3/library/functions.html#eval), but because it can execute arbitrary code, we opt to use a custom tokenizer and evaluator for safety, instead..

Let's not delve into the implementation details but rather focus on a test:

def test_formula_parsing():
    tokenizer = FormulaTokenizer()
    formula = Formula.from_string("C0 * x + 10", tokenizer)
    assert formula.eval(x=1.0, C0=2.0) == pytest.approx...