main - here are our source codes, with working functionalities → SourceCodeClass.java
test - here are test classes, that check whether source code is working properly. This is where our JUnit5 is used → TestClass.java

Running tests

From shell

Note
Remember to install Maven & Java 8!

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Panel

After we have set up the code for the testing, we can run the tests and find out if the tested methods are working correctly.

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To run all tests in a test class, click against the test class declaration and select Run.
To run an individual test, click Image Added in the gutter and select Run.

You can view test results in the Run tool tool window at the bottom of IDE.