So far so good for the initial 36 test cases in the example. A second python script is now used to split the large sequence of 365 test cases into nine sequences of 37 test cases, and one of 32 test cases. It is used in conjunction with a batch file that the leverages the tool’s command line interface to automate the execution of all the sequences.

After the tests have run the report can be viewed, and it can be seen that a single test case has failed. The green phase continues until an answer to that problem is found.

Figure 11: Failure due to accessing an out of bounds value

Inspection reveals that the test case that sets the value of the angle to 90° fails as a result of accessing a value outside the bounds of the lookup table (Figure 11). The lookup table has 90 elements meaning that indices of 0-89 are valid, but this index of 90 is not.

Without performing Test-Driven Development, this bug might not have been found!

Fourth iteration: Expanding the test set (green phase)