Expectations are self-concatenated strings that evaluate an actual value to an expected value or condition. These are initiated by the global TestBox method called expect() which takes in a value called the actual value or expectAll() which takes in an array or struct which will be the actual value. It is concatenated in our expectations DSL with a matcher function that will most likely take in an expected value or condition to test. You can also concatenate the matchers and do multiple evaluations on a single actual value.
Each matcher implements a comparison or evaluation of the actual value and an expected value or condition. It is responsible for either passing or failing this evaluation and reporting it to TestBox. Each matcher also has a negative counterpart assertion by just prefixing the call to the matcher with a not expression.