You are undoubtedly doing some form of Approval testing already. The most basic form would be writing REQUIRE(42 == 6 * 9), then running it, getting the result 42 != 54 and then changing the code to say REQUIRE(54 == 6 * 9).
This is the path that we commonly see, as people move in to Approval Tests:
- Verify numbers
- Have lots of numbers, like an array
- Strings - turn the array of numbers in to a string
- Those strings become long
- Files - Golden Master
- Managing them - coming up with names
- Some sort of naming convention
- Can be hard to understand what's in the files
- Start using diff tools
- Start creating custom methods for the things you are testing
- verifyThing