Testing

Checking that a program does what it should, by deciding the right outputs for chosen inputs first and letting code such as assert compare them every time the program changes.

Depth 1 · Foundation

You can write test cases before the code, choose inputs at the boundaries, check them with assert in a test function, test that bad input is refused, and know that passing tests show bugs' presence, never their absence.

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Depths of understanding

1
Foundation
You can write test cases before the code, choose inputs at the boundaries, check them with assert in a test function, test that bad input is refused, and know that passing tests show bugs' presence, never their absence.
Opens after
Edge casesGood test cases are mostly edge cases, the values where a rule changes.Exceptionsassert works by raising an exception, and a test often checks that bad input raises one.

Your path here

What's still between you and Testing, depth 1, in the order you can learn it.

Where it fits

Builds on

Edge cases Exceptions

This concept

TestingWriting Correct Code

Opens up

Builds onThis conceptOpens upEdge cases Exceptions TestingWriting Correct Code Debugging

Makes these deeper

Once you know Testing, come back to these — they'll mean more.

DecompositionDepth 2A plan is checked piece by piece, so each part of the design comes with tests.