Blackbox vs Glassbox

No, they're not window managers

Blackbox tests use only the public, documented API

• No cheating

• You have to forget how the code is implemented

• More closely approximates real world usage

• Immune from internal changes

• Often forces you to make the public API more flexible

Glassbox tests can use whatever you want

• Cheat, steal, lie, violate encapsulation

• Often necessary to test certain 'untestable' parts

• My be broken by internal changes, undermines the test suite

Blackbox is preferred where possible

Glassbox is sometimes necessary

• Sometimes you can just peek inside the box

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