Junit @BeforeClass 看不懂

Question

这是我的测试类。我尝试解析 CSV 文件并创建一个 Object[][]（调用 data）。当我尝试给 data 作为参数时，它会调用空指针。我不知道为什么会失败。当我提供硬核代码之类的数据时，它确实有效。请解释一下，我不明白

@RunWith(Parameterized.class)
public class TestJUnit {

public int firstParameter;
public int secondParameter;
public String operation;
public int expectedResult;

public static Object[][] data;

public TestJUnit(int firstParameter, int secondParameter, String operation, int expectedResult) {
    this.firstParameter = firstParameter;
    this.secondParameter = secondParameter;
    this.expectedResult = expectedResult;
    this.operation = operation;

}

    @BeforeClass
    public   void makeData() throws IOException {

        BufferedReader reader = new BufferedReader(new FileReader("C:\Users\third\IdeaProjects\MyJunit\src\test\java\com\myLogicTest\datafile.csv"));

        ArrayList<Object[]> tempArray = new ArrayList<Object[]>();
        String newLine;
        Object[] oneString;
        while ((newLine = reader.readLine()) != null) {


            oneString = newLine.split(";");
            tempArray.add(oneString);
        }
        data = new Object[tempArray.size()][];
        for (int i = 0; i < data.length; i++) {
            Object[] row = tempArray.get(i); data[i] = row; }
        }

    @Test
public void checkCalculator() {
        final Calculator calculator = new Calculator(firstParameter, secondParameter, operation);
        int result;
        if (operation.equals("*")) {
            result = calculator.multi();
            Assert.assertTrue("Результат (" + result + ") не равен" + expectedResult, result == expectedResult);
        }
        else if (operation.equals("+")) {
            result = calculator.plus();
            Assert.assertTrue("Результат (" + result + ") не равен" + expectedResult, result == expectedResult);
        }
        else if (operation.equals("-")) {
            result = calculator.minus();
            Assert.assertTrue("Результат (" + result + ") не равен" + expectedResult, result == expectedResult);
        }
        else if (operation.equals("/")) {
            result = calculator.del();

            Assert.assertTrue("Результат (" + result + ") не равен" + expectedResult, result == expectedResult);
        }

        }


    @Parameterized.Parameters(name = "{index}: Действие {0} {2} {1} = {3}")
    public static Collection<Object[]> getTestData() {
        return Arrays.asList(data
                /* new Object[][]{    //<<<NULLPOINTER HERE
                {2, 2, "*", 4},
                {2, 0, "+" , 2},
                {2, 2,"/", 1},
                {0, 2,"-",-2}
        }*/);
    }
}

Answer 1

问题出在注释@BeforeClass 中，当我们使用参数化测试时，@Before 和@BeforeClass 运行不是第一次！就我而言，我需要在方法 getTestData() 中调用方法 makeData()，如下所示：

@Parameterized.Parameters(name = "{index}: Действие {0} {2} {1} = {3}")
public static Collection<Object[]> getTestData() {
    makedata(); // <<<<<I NEED USE IT HERE!
    return Arrays.asList(data
            /* new Object[][]{    //<<<NULLPOINTER HERE
            {2, 2, "*", 4},
            {2, 0, "+" , 2},
            {2, 2,"/", 1},
            {0, 2,"-",-2}
    }*/);

Junit @BeforeClass 看不懂

Junit @BeforeClass don't understand

unit-testing

junit4