Lesson 2.5: Test levels

An overview page: the slides of this lesson contain the slides of the three level pages below as nested sets.

1. Why levels

• Each level of test answers a different question.
• A cheap test at a low level finds a fault sooner than an expensive test at a high level.
• Together the levels form the test pyramid.

2. The levels

• Unit tests
• Integration tests
• End-to-end tests

3. Choosing a level

• Test a rule at the lowest level that can show it.
• Test a connection between parts at the integration level.
• Test a whole journey of a user at the end-to-end level, and only a few of them.