2.5、Assumptions

JUnit Jupiter包含一部分JUnit4得假设方法，还新增加了能与Java8得lambda表达式和方法引用结合很好得假设方法。所有得JUnit Jupiter假设方法都在org.junit.jupiter.api.Assumptions类得静态方法。

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));
    }

}

在JUnit Jupiter 5.4版本中，是允许使用JUnit4得org.junit.Assume类来假设。具体说，JUnit Jupiter支持JUnit4得AssumptionViolatedException来表示一个方法应该被终止而不是标记为失败。