Assumptions are used to run tests only if certain conditions are met. This is typically used for external conditions that are required for the test to execute properly, but which are not directly related to whatever is being unit tested.
assumeTrue() condition is true, then run the test, else aborting the test.
assumeFalse() condition is false, then run the test, else aborting the test.
assumingThat() is much more flexible, it allows part of the code to run as a conditional test.