GENERAL KNOWLEDGE /
TESTS

Before any application is deployed, tests are needed in order to make it sure that for functionality, robustness and performance the application is trustable.

Tests are divided to test cases. A test case represents a certain group of incoming data and checks against the results. The test cases together must cover all possibilities, also it is essential that the test strategy should follow the design.

A well-designed test series makes it sure that if passes, the code is in proper status and works within the needed parameters. Also, when a test case fails, that marks properly that the code lost it properness and helps to identify the source of error.

The tests should cover normal cases (when the code is used within ideal parameters) and edge cases (when the code flow is under stress, e.g. against null or maximum input values) as well.

There are several test strategies:

• unit tests

• behaviour tests

• integration tests

A unit test goes through all public part of that unit (e.g. on class, interface, method level etc.) and examines that unit independently for test cases.

Due to having independent unit tests, when the tested unit changes but the purpose of it does not, it is enough to re-run the corresponding unit test.

Best practice is to make a test as independent as it is possible. In most cases, an application contains several application layers (e.g. Storage, Business, Communication for backend), many classes and other units. When a test case is well-separated from the others, in case that test fails, will point out the exact source of the fail.

A behaviour test examines not all cases for a unit but how it will work (behave) when invoked or used.

Typical situation is when simple classes (made of fields, constructors and getters-setters only) need testing, e.g. will the object constructed when wrong data is passed.

An integration test serves as general test which examines how two or more units work together, or how the whole application works.

Typical integration test for a backend is having external cURL test cases.

Other typical version is when two layers are tested together and connections with other layers are mocked out.

At the point of examination, use an assertion (Java core) or the Assertions class of JUnit.

In case an independent unit test would not run without invoking other units in the process, best practice is to use the Mockito framework to emulate working of the other unit.

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