Test-driven development (TDD) is a very useful method for designing software. The method is as follows—we first write one single test that fails, then we implement the minimum code to make the test pass, and finally we refactor. We do this in small cycles in quick succession.
We will look at how pure functions simplify tests and provide an example of applying TDD with functions. Pure functions allow us to write simple tests because they always return the same values for the same input parameters; therefore, they are equivalent to big data tables. We can therefore write tests that emulate data tables for inputs and the expected outputs.
The following topics will be covered in this chapter:
- How to use data-driven tests to take advantage of pure functions
- Understanding the basics of the TDD cycle
- How to design a pure function...
