MEPX
Chapter 9 of 10All chapters
  1. 1Why test
  2. 2Kinds of test
  3. 3What a good test looks like
  4. 4Fakes, stubs and mocks
  5. 5Coverage and flakiness
  6. 6Reproducing a bug
  7. 7Narrowing it down
  8. 8Reading the evidence
  9. 9Debuggers and tools
  10. 10The hard ones

Chapter 9 of 10

Debuggers and tools

Beyond printing values.

Using a debugger

A breakpoint pauses execution so you can inspect every variable and step line by line. Conditional breakpoints stop only when a value matches, which finds the one bad iteration in a million.

  • Print statements are fine and fast; a debugger is better once the state is complex.
  • The browser and most editors have one built in already.

Other instruments

A profiler shows where time goes, a memory tool shows what is not being freed, and the network tab shows what was actually sent. Each answers a question guessing cannot.