Test Array Sum

Geoffrey Challen // 2020.10.0

Create a method named test accepting a single parameter: an instance of ArraySum.

Each ArraySum provides a method sum that accepts an Array<Int> and returns the sum of the values as an Int, or 0 if the array is null. However, some ArraySum implementations are broken! Your job is to identify all of them correctly.

To do this you should use assert to test various inputs. Here's an example:

Your function does not need to return a value. Instead, if the code is correct no assertion should fail, and if it is incorrect one should.

As you design test inputs, here are two conflicting objectives to keep in mind:

  • Less is more. The fewer inputs you need to identify all broken cases, the more readable your test suite will be.
  • Think defensively. At the same time, you want to anticipate all of the different mistakes that a programmer might make. You've probably made many of these yourself! Examples include forgetting to check for null, off-by-one errors, not handling special cases properly, etc.

Good luck and have fun!