The test/suite directory includes a collection of Python unit tests that are expected to be executed when code change is introduced in this repo. These Python tests are broken down and grouped into multiple buckets/tasks in Evergreen (CI system) configuration. See test/evergreen.yml for details. There is a plan to implement a mechanism to auto-group tests into buckets/tasks based on history runtime of each test, and generate the Evergreen configuration dynamically before each Evergreen build variant run, so that no mental overhead is required when new tests is introduced into test/suite. (WT-4441) Before the above mentioned mechansim is put into place, please double check test/evergreen.yml and test run logs to make sure new test are covered.