# Util suite A **util suite** is a struct which provides specific setup and teardown behavior as well as useful variables and functions to write [unit test suites](https://documentation.ubuntu.com/juju/4.0/contributor/reference/testing/unit-testing/unit-test-suite.md#unit-test-suite) suites with. There are several util suites, among which: * `/testing.BaseSuite` (`testing/base.go`) * `/testing.FakeHomeSuite` (`testing/environ.go`) * `/testing.FakeJujuHomeSuite` (`testing/environ.go`) * (DEPRECATED) `/juju/testing.JujuConnSuite` (`juju/testing/conn.go`) The last three have the BaseSuite functionality included through composition. The BaseSuite isolates a user’s home directory from accidental modification (by setting `$HOME to ""`) and errors if there is an attempt to do outgoing HTTP access. It also clears the relevant `$JUJU_* environment variables`. The `BaseSuite` is also composed of the core `LoggingSuite`, and also `LoggingSuite` from `github.com/juju/juju/internal/testhelpers`, which brings in the `CleanupSuite` from the same. The `CleanupSuite` has functionality around patching environment variables and normal variables for the duration of a test. It also provides a clean-up stack called when the test teardown happens. If you need additional functionality, you can embed one of the suites below: * BaseSuite * FakeHomeSuite: creates a fake home directory with `~/.ssh` and fake ssh keys. * FakeJujuHomeSuite: as above but also sets up a `~/.config/juju` with a fake model. * (DEPRECATED) JujuConnSuite: Simulates a controller and an API server as well as a database. Quite heavy weight. Can be useful in that it simulates a Juju environment as closely as possible.