为什么Junit不能在测试中执行依赖注入？开发者社区

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public class Calculator {
    public int subtract(int a, int b) {
        return a - b;
}

import lombok.AllArgsConstructor;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;
@AllArgsConstructor
class CalculatorTest {
    private final Calculator calculator;
    private static final int SUBTRACTION_RESULT = 2;
    @Test
    void subtractTest() {
        int result = calculator.subtract(5, 3);
        assertEquals(result, SUBTRACTION_RESULT);
}

org.junit.jupiter.api.extension.ParameterResolutionException: No ParameterResolver registered for parameter [final com.udemy.junits.Calculator calculator] in constructor [public com.udemy.junits.CalculatorTest(com.udemy.junits.Calculator)].

public CalculatorTest(Calculator calculator) {
    this.calculator = calculator;
}

@BeforeAll
    static void init() {
        calculator = new Calculator();
    }

public class Calculator {
    public int subtract(int a, int b) {
        return a - b;
@RequiredArgsConstructor
@RunWith(Parameterized.class)
class CalculatorTest {
    private final int x;
    private final int y;
    private final int z;
    private Calculator calculator;
    // Constructor is generated by lombok with @RequiredArgsConstructor
    // and accepts three parameters, x, y, and z
    @BeforeEach
    void setUp() {
        calculator = new Calculator();
    @Test
    void testSubtract() {
        assertEquals(z, calculator.subtract(x, y));
     * This method will pass each parameter into the constructor
     * of this test class. In this case, the testSubtract method
     * will be ran 4 times with each set of parameters.
    @Parameterized.Parameters
    static Collection parameters() {
        return Arrays.asList(
            new Object[][] {
               {5, 3, 2},
               {10, 1, 9},

问 为什么Junit不能在测试中执行依赖注入？

回答 1

Stack Overflow用户