test: add and refactor tests
This PR adds initial integration tests for the DockerTest
crate, refactors existing tests, and adds more internal testing as well.
Existing test utility functions have been move to a separate private module.
Previously, these were contained in the test module for ImageInstance
, however, the functionality was needed
elsewhere.
To avoid code duplication, the new private module test_utils
was added and is responsible for providing utility functions for test environments.
Edited by Jon Foss Mikalsen