实际数组为NULL-JUnit

Question

我正在尝试单元测试我的覆盖文件的方法（或者创建一个新的，如果给定的文件不存在）。我的想法是在覆盖之前和覆盖之后比较两个数组，所以我做了它，但不幸的是，它说实际数组是空的。我正在使用TemporaryFolder，这样在测试后可以很容易地删除它。

方法我想要单元测试+方法，这是测试覆盖方法所需的。

package rankingsystem;

import contentfile.ContentFileRetriever;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.*;
import java.util.stream.Collectors;

public class RankingSystemService {

    private ContentFileRetriever contentFileRetriever;

    public RankingSystemService(ContentFileRetriever contentFileRetriever) {
        this.contentFileRetriever = contentFileRetriever;
    }

    ...

    String[] retrieveRankingData(String rankingPathFile) {
        return contentFileRetriever.getContent(rankingPathFile);
    }

    void overwriteFileWithGivenResult(String name, long timeOfFinishingGame, String rankingPathFile) {

        try (FileWriter writer = new FileWriter(rankingPathFile, true);
             BufferedWriter bufferedWriter = new BufferedWriter(writer)) {
            bufferedWriter.write(name + " " + timeOfFinishingGame);
            bufferedWriter.newLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class RankingSystemServiceTest {

    @Rule
    public TemporaryFolder tempFolder = new TemporaryFolder();

    @Mock
    ContentFileRetriever contentFileRetriever;

    private RankingSystemService rankingSystemService = new RankingSystemService(contentFileRetriever);

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(this);
        rankingSystemService = new RankingSystemService(contentFileRetriever);
    }


    @Test
    public void overwriteFileWithGivenResult() throws IOException {
        File rankingFile = tempFolder.newFile("rankingText.txt");
        String rankingFilePath = rankingFile.getPath();

        String[] actualResultBeforeOverwriting = rankingSystemService.retrieveRankingData(rankingFilePath);
        String[] expectedResultBeforeOverwriting = {};

        assertArrayEquals(expectedResultBeforeOverwriting, actualResultBeforeOverwriting);

        rankingSystemService.overwriteFileWithGivenResult("Piotr", 1L, rankingFilePath);

        String[] afterOverwriting = rankingSystemService.retrieveRankingData(rankingFilePath);
        String[] expectedResultAfterOverwriting = {"Piotr 1"};

        assertArrayEquals(expectedResultAfterOverwriting, afterOverwriting);
    }

@Override
    public String[] getContent(String pathName) {

        try (Stream<String> contentFileStream = Files.lines(Paths.get(pathName))) {
            return contentFileStream.toArray(String[]::new);
        } catch (IOException e) {
            throw new IllegalArgumentException(e);
        }
    }

java.lang.AssertionError: actual array was null

    at org.junit.Assert.fail(Assert.java:88)
    at org.junit.internal.ComparisonCriteria.assertArraysAreSameLength(ComparisonCriteria.java:71)
    at org.junit.internal.ComparisonCriteria.arrayEquals(ComparisonCriteria.java:37)
    at org.junit.Assert.internalArrayEquals(Assert.java:532)
    at org.junit.Assert.assertArrayEquals(Assert.java:283)
    at org.junit.Assert.assertArrayEquals(Assert.java:298)
    at rankingsystem.RankingSystemServiceTest.overwriteFileWithGivenResult(RankingSystemServiceTest.java:61)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.rules.ExternalResource$1.evaluate(ExternalResource.java:48)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Answer 1

根据JB Nizet用户的要求，我需要删除ContentFileRetriever的mock并创建ContentFileRetriever的实例，它可以工作。

ContentFileRetrieverService contentFileRetrieverService = new ContentFileRetrieverService();