Here are a few items I try to respect every time I write unit tests.

  • My test class is testing one and only one class
  • My methods are testing one and only one method at a time
  • My variables and methods names are explicit
  • My test cases are easy to read by human
  • My tests are also testing expected exception with @Test(expected=MyException.class)
  • My tests don’t need access to database
  • My tests don’t need access to network resources
  • My tests respect the usual clean code standards (length of lines, cyclomatic complexity,…)
  • My tests control side effects, limit values (max, min) and null variables (even if it throws an exception)
  • My tests can be run any time on any place without needing configuration
  • My tests are concrete (ex. dates are hardwired, not computed every time, strings too…)
  • My tests use mock to simulate/stub complex class structure or methods
I’m pretty sure there are more.  Any idea ?