Approval Testing

• Test behaviour not code
• If behaviour isn’t simple, stable and well defined, don’t use assertions
• Capture system behaviour, filter it and manage things in it
• Approval testing - reject it (a bug), intentional change, or ignore it (we don’t care)
• Blacklisting vs Whitelisting
• More checks implies more effective but less maintainable
• Assertion based checking - start checking nothing but blacklist outcomes up front - repeat until bored - what are all failure modes
• Approval checking - start checking everything and whitelist outcomes on demand - repeat until maintenance feels manageable - is this change correct, incorrect, or uninteresting
• Legacy code - correct behaviour is what it does now - cannot change to get it under test, APIs may be lacking
• Characterization testing - what it does
• TextTest.org (open source)
• http://www.methodsandtools.com/archive/archive.php