Assertions

The Assertions class contains static methods for use in test cases. * This class is in the org.junit.jupiter.api package.

assertEquals(a, b, message) and assertNotEquals

Check equality or inequality of two things.

This has changed from JUnit 4; the optional message is now the last parameter.

assertTrue and assertFalse

These are the same as JUnit 4, but with the message as the last parameter.

Executable Interface and Assertions

A major change in JUnit 5 is that many assertions take an implementation of the org.junit.jupiter.api.function.Executable functional interface.

public interface Executable {
  void execute();
}

We can use lambda expressions to create these instances.

One such assertion is assertAll(Executable... executables)

assertAll(Executable... executables)

This allows us to group assertions. * Any failures will be reported together. * This also asserts that all supplied executables do not throw exceptions.

@Test
@DisplayName("Failure Example")
void testDepositing() {
  account.deposit(50);
  assertAll(
      () -> assertEquals(150, account.getBalance())
      ,
      () -> assertEquals(550, account.getBalance()) // fail
      ,
      () -> assertEquals(999, account.getBalance()) // fail
  );
}

org.opentest4j.MultipleFailuresError: Multiple Failures (2 failures)
    expected: <550.0> but was: <150.0>
    expected: <999.0> but was: <150.0>

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