Pillar 4 – Test runner and test isolation

Goal: Understand what a test runner and its test isolation are and learn how to use and apply them.

Given the previous three pillars, we are positioned to write test cases as follows:

• Using test codeunit and test functions
• Either sunny or rainy path, the latter by applying the asserterror keyword
• With fully automated execution addressing any user interactions by applying handler functions

Do we need more?

As a matter of fact, yes, we do, as we need a way to do the following:

1. Run tests stored in multiple codeunits, control their execution, and collect and secure the results
2. Run tests in isolation, so that we can achieve the following:
   • Write transactions, in the end, do not alter the database we run the test on
   • Each rerun of a test is done using the same data setup

Both goals can be accomplished using a so-called TestRunner codeunit with a certain test isolation. A test runner codeunit is defined by its Subtype and the isolation by its TestIsolation:

codeunit Id MyTestRunnerCodeunit
 {
     Subtype = TestRunner;
     TestIsolation = Codeunit;
 }