Assertion

Finding a value in a sorted range by repeatedly discarding half of it.

A snapshot of a crashed program's memory saved for later inspection, how to get one, how to read one, and why it can leak secrets.

Writing code that anticipates misuse and bad input, checking assumptions and handling the unexpected rather than trusting callers, along with the debate over when defense should give way to failing loudly.

Specifying what each function requires and guarantees, as checkable preconditions, postconditions, and invariants, so a violation says exactly whose bug it is.

Crash at the point of misconfiguration rather than degrading quietly into a wrong state.

A claim is only worth something if you know what observation would refute it.

Comparing an output against a checked-in reference file the whole team agreed was correct, rather than an inline assertion.

Using a language model to score another model's output against a rubric.

A test-of-tests that injects small bugs into code and checks whether the existing suite catches them, exposing tests that assert nothing.

The property that identical inputs may produce different outputs, and what it costs to test around.

Running one test body against a table of inputs and expected outputs, so each case is a single readable row and each failure is reported on its own.

Asserting a general property that should hold for all inputs, then letting the framework generate many random inputs to try to break it.

Comparing a component or output's current rendering against a saved baseline, flagging any difference for a human to accept or reject.

Whatever decides whether a test's output is correct, and the often-overlooked hard part of testing when nobody knows the right answer in advance.

Writing a failing test first, making it pass, then improving the code with the test as a net.

A statement that holds only because its subject set is empty — a green result that measured nothing.