Kent Beck: Why Composable Tests Beat Isolated Ones

Kent Beck: Composable Tests

Kent Beck explains why test isolation isn't the same as test composition. He argues that while isolated tests are predictable, composing them—by trimming redundant assertions—can make suites faster, more readable, and more specific. Using an example of interest computation and reporting, he shows how 10 composed tests can give the same confidence as 20 brute-force ones, and he pushes back on the fear of reducing assertions.