What to test
Before we go into the topic of how to craft effective, fast, reliable, automated, and maintainable test cases, let's have a look at what assets to test. There are tests on a code layer as well as end-to-end tests. Code layer tests are based on the project's source code and are usually executed during development and build time, whereas end-to-end tests, of all kinds, operate on a running application.
Depending on the test scopes, which we will get to know in the next section, there are different layers of tests, whether tests operate on classes, multiple components, enterprise applications, or whole environments. In all cases the test object needs to be isolated from external concerns. The nature of tests is that they verify certain behavior under specific conditions. The environment surrounding the test object, such as the test cases as well as used components, have to interact with the test object accordingly. The test case will therefore control the test object. This not only...
