Assumptions

Assumptions are typically used whenever it does not make sense to continue execution of a given test — for example, if the test depends on something that does not exist in the current runtime environment.

When an assumption is valid, the assumption method does not throw an exception, and execution of the test continues as usual.
When an assumption is invalid, the assumption method throws an exception of type org.opentest4j.TestAbortedException to signal that the test should be aborted instead of marked as a failure.

JUnit Jupiter comes with a subset of the assumption methods that JUnit 4 provides and adds a few that lend themselves well to being used with Java 8 lambda expressions and method references.

All JUnit Jupiter assumptions are static methods in the org.junit.jupiter.api.Assumptions class.

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assumptions.assumeTrue;
import static org.junit.jupiter.api.Assumptions.assumingThat;

import example.util.Calculator;

import org.junit.jupiter.api.Test;

class AssumptionsDemo {

	private final Calculator calculator = new Calculator();

	@Test
	void testOnlyOnCiServer() {
		assumeTrue("CI".equals(System.getenv("ENV")));
		// remainder of test
	}

	@Test
	void testOnlyOnDeveloperWorkstation() {
		assumeTrue("DEV".equals(System.getenv("ENV")),
			() -> "Aborting test: not on developer workstation");
		// remainder of test
	}

	@Test
	void testInAllEnvironments() {
		assumingThat("CI".equals(System.getenv("ENV")),
			() -> {
				// perform these assertions only on the CI server
				assertEquals(2, calculator.divide(4, 2));
			});

		// perform these assertions in all environments
		assertEquals(42, calculator.multiply(6, 7));
	}

}

It is also possible to use methods from JUnit 4’s org.junit.Assume class for assumptions. Specifically, JUnit Jupiter supports JUnit 4’s AssumptionViolatedException to signal that a test should be aborted instead of marked as a failure.