Self-tests → used as an additional check in the system complementary to the test suite

Assertions

• A boolean expression at a specific point in a program.
• In java asserts can be enabled or disabled (then they will never throw an error)
• In intelliJ these are automatically enabled. Otherwise add -ea (enable assertions)
• However these do no replace unit tests
• Assert
• Assertion Error
• Example

Pre & Post Conditions

• Hoare Triples
• Pre-Conditions
• Post-Conditions

Invariants

These are conditions that always need to hold, before and after a method's execution.

• Checker method