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Your first real test

One assertion is not a test suite. Prove it.

Beginner10 min on the clock4 graded checks · 100 pointsTests That Catch Bugs

Graded by running your code against real cases.

What you build

Assert that add returns the right answer for one pair of numbers
Add a second pair with a DIFFERENT answer
Check that both arguments are actually used
Include a zero and a negative number

Done means

Your suite passes a correct add and fails four broken ones.

How it is graded

Published in full, before you start — every point is one of these and there is nothing else. Each one runs your code; it is not a search for keywords.

It catches a function that always returns 5+30What a test actually is
It catches multiplication pretending to be addition+25What a test actually is
It catches a function that ignores the second argument+25What a test actually is
It catches subtraction+20What a test actually is

What it teaches

What a test actually isbeginner

A test is a comparison that throws when it is wrong — and one example proves almost nothing, because a function that always returns the same answer will pass it.

The rest of Tests That Catch Bugs

The cases nobody writesBeginner · 12 min One either sideBeginner · 12 min Testing what you cannot seeIntermediate · 18 min The failure pathIntermediate · 18 min Rules, not examplesAdvanced · 22 min