There are several angles to go about writing tests for code, and it is important to understand them before you start avoiding some of the bad practices. Tests written without a clear intent by the programmer are often characterized as being too long or asserting too much.
The most important aspect of unit tests is to assert the code has the intended result when executed. It is important that the author of the tests is the same as that of the code, or some of the intent might be lost in the process.
The following is a code snippet:
// System Under Test let div x y = x / y // Test div 10 2 |> should equal 5
This might state the obvious, but a developer could easily mix up the order of incoming arguments:
// System ...