unit-tests.md

Unit tests

Project unit tests use JUnit as a main testing framework. Also used AssertJ for checking assertions and Mockito for mocking objects.

In general, for testing the behavior of some class use the following rules:

• check instance creation of tested object (if non-static)
• check all negative scenarios with possible exceptions
• check all positive scenarios

Writing the unit tests considers Given-When-Then style. For example:

@Test
public void someTest() {
    // given
    int a = 2;
    int b = 2;
    
    // when
    int c = a + b;
    
    // then
    assertThat(c).isEqualTo(4);
}

It is preferable to use fluent assertions:

assertThat(result)
    .isNotNull()
    .extracting(r -> r.errors).isEmpty();

Unit tests can use static method imports, like:

import static java.util.Collections.emptyList;

//...

someService.perform(emptyList());

Unit tests can use resources from "src/test/resources" folder.

In case your business logic uses JSON manipulation, unit tests must be inherited from org.prebid.server.VertxTest class. Thus, application preconfigured JSON mapper will be used.

To run the project unit tests execute:

mvn clean test