Assertion
In plain terms
A statement in a test that checks an expected condition.
Going deeper
An assertion verifies that a value or behavior matches expectations, failing the test if not. It's how tests declare what 'correct' means.
Under the hood
The core of automated tests; good assertions are specific and produce clear failure messages.
Examples
assertEqual, expect(x).toBe(y), test conditions, validation checks.
Think of it like...
Like a checklist item that must be ticked true or the inspection fails.