Java 如何对依赖于其他方法的方法进行单元测试

我有以下方法

public static File getInventoryFileFromProperties(){
    String filePath = getProperty(ConfigProperties.MY_INVENTORY_FILE);
    logger.debug("Looking for inventory file at {}", filePath);

    return new File(filePath);
}

如何针对以下情况进行单元测试，ConfigProperties.MY_INVENTORY_文件不在属性文件中

getProperty() // gets values from property file
ConfigProperties.MY_INVENTORY_FILE // is an enum of keys 

---

使访问外部资源（如文件系统）的代码可进行单元测试的最佳方法是创建一个抽象层，例如：

然后，可以通过依赖项的构造函数注入重构被测试的类以使用资源访问器：

public class ContainingClass {

    private FileAccessor fileAccessor;

    // this constructor is accessible for the unit tests
    ContainingClass(FileAccessor fileAccessor) {
        this.fileAccessor = fileAccessor;
    }

    // this constructor is used by normal client code
    public ContainingClass() {
        this(new FileAccessor());
    }

    public File getInventoryFileFromProperties(){
        String filePath = fileAccessor.getProperty(ConfigProperties.MY_INVENTORY_FILE);
        return fileAccessor.createFile(filePath);
    }
}

最后，单元测试变得更简单，因为您可以模拟文件访问。此测试使用模拟框架模拟依赖项，并且也适用于JUnit的早期版本：

import static org.mockito.Mockito.*;
import org.junit.Test;

public class ContainingClassTest {

    @Test
    public void getInventoryFileFromProperties_MY_INVENTORY_FILE_isMissing() {

        FileAccessor fileAccessor = mock(FileAccessor.class);

        // arrange the config file to return a null value for the property
        when(fileAccessor.getProperty(ConfigProperties.MY_INVENTORY_FILE)).thenReturn(null);

        // act; call the method
        new ContainingClass(fileAccessor).getInventoryFileFromProperties();

        // assert that the file-creating method was called with a null path
        verify(fileAccessor).createFile(isNull(String.class));
    }
}

---

您是否可以修改

getInventoryFileFromProperties（）

和包含的类以使其更容易进行单元测试，或者您是否正在寻找方法以测试代码的现状？

import static org.mockito.Mockito.*;
import org.junit.Test;

public class ContainingClassTest {

    @Test
    public void getInventoryFileFromProperties_MY_INVENTORY_FILE_isMissing() {

        FileAccessor fileAccessor = mock(FileAccessor.class);

        // arrange the config file to return a null value for the property
        when(fileAccessor.getProperty(ConfigProperties.MY_INVENTORY_FILE)).thenReturn(null);

        // act; call the method
        new ContainingClass(fileAccessor).getInventoryFileFromProperties();

        // assert that the file-creating method was called with a null path
        verify(fileAccessor).createFile(isNull(String.class));
    }
}