java - 单元测试目录是否存在 - Junit

Question

我有一个函数可以用来检测某个目录路径是否存在。这是函数:

public boolean isRunningOnSandbox() {
   return Files.isDirectory(Paths.get("/mySandbox/cloud/sandbox"));
}

如您所见，它依赖于静态方法 isDirectory。在我的团队中，我们不使用 PowerMock 进行测试。

那么，我该如何测试这个方法呢？我尝试编写如下测试:

@Rule
public TemporaryFolder temporaryFolder;

@Test
public void test() throws IOException {
    File parent = new File("/");
    temporaryFolder = new TemporaryFolder(parent);
    temporaryFolder.create();
    File folder = temporaryFolder.newFolder("mySandbox", "cloud", "sandbox");
    subject.isRunningOnSandbox();
}

但是，我得到一个错误

ava.io.IOException: Permission denied

因为它不允许我在根目录下创建一个临时文件夹。我猜想有一种更好的方法来测试这段代码，而不是尝试创建一个文件夹。

Answer 1

有很多方法可以做到，其中一种可能像下面的方法。
假设 isRunningOnSandbox 方法在某个类 SomeClass 中，然后以这种方式重构这个类:

public class SomeClass {

    public boolean isRunningOnSandbox() {
        return Files.isDirectory(Paths.get(getSanboxPath()));
    }

    protected String getSanboxPath(){
        return "/mySandbox/cloud/sandbox";
    }
}

然后在您的测试中将另一个您有权访问的目录注入(inject)此类，例如:

public class SomeClassTest {

    class SomeClassToTest extends SomeClass{
        String folder;
        public SomeClassToTest(String folder){
            this.folder = folder;
        }
        @Override
        protected String getSanboxPath(){
            return folder;
        }
    }

    static String sandboxFolder = "myTestSandobxFolder";

    static Path tempDir;

    @BeforeClass
    public static void createFolder() throws IOException {
        tempDir = Files.createTempDirectory(sandboxFolder);
    }

    @AfterClass
    public static void deleteFolder() throws IOException {
        Files.delete(tempDir);
    }

    @Test
    public void IsRunningOnSandbox_shouldReturnTrueWhenPathExists() throws IOException {
        //given
        SomeClass testedObject = new SomeClassToTest(tempDir.toString());
       //when
        boolean result = testedObject.isRunningOnSandbox();
        //then
        assertThat(result).isTrue();
    }

    @Test
    public void IsRunningOnSandbox_shouldReturnFalseWhenPathDoesNotExist() throws IOException {
        //given
        SomeClass testedObject = new SomeClassToTest("/abcdef123");
        //when
        boolean result = testedObject.isRunningOnSandbox();
        //then
        assertThat(result).isFalse();
    }
}