Mockito for Environment getExternalStorageState() android

Question

我是mockito测试的新手，我一直在努力关注博客，但现在很混乱。

座右铭是测试FileUtility类中的两个静态函数。代码如下。

public static boolean isExternalStorageWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
return true;
}
return false;
}
public static String getLogFilePath(String fileName) {
if (isExternalStorageWritable()) {
File _file;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
_file = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DOCUMENTS);
if (exists(_file)) {
return getAbsoluteFilePath(_file,fileName);
}
}
_file = Environment.getExternalStorageDirectory();
if (exists(_file)) {
return getAbsoluteFilePath(_file,fileName);
}
}
File _file = Environment.getDataDirectory();
if (exists(_file)) {
return getAbsoluteFilePath(_file,fileName);
}
return fileName;
}
private static boolean exists(File file) {
return file != null && file.exists();
}

我应该如何编写单元测试用例来测试该函数的输入，如"fileName=null"？

请分享一些光/代码。

Answer 1

看起来有三条主要路径通过getLogFilePath():

• 如果外部存储是可写的，并且外部存储公用目录可用，则使用它
• 如果外部存储是可写的，并且外部存储公用目录不可用，但外部存储目录可用，则使用它
• 在所有其他情况下，使用数据目录

编写这些测试用例只涉及对以下方法的一些模拟期望：

• Environment.getExternalStorageState()
• Environment.getExternalStoragePublicDirectory()
• Environment.getExternalStorageDirectory()
• Environment.getDataDirectory()

这里有一个例子：

// this test case need to mock static methods so it uses PowerMock
@RunWith(PowerMockRunner.class)
// this static methods to be mocked are on Environment so that must be 'prepared'
@PrepareForTest({Environment.class})
public class StorageUtilsTest {
@Rule
public TemporaryFolder storageDirectory = new TemporaryFolder();
private File nonExistentDirectory;
private File existentDirectory;
@Before
public void setup() {
nonExistentDirectory = Mockito.mock(File.class);
Mockito.when(nonExistentDirectory.exists()).thenReturn(false);
existentDirectory = storageDirectory.getRoot();
PowerMockito.mockStatic(Environment.class);
}
@Test
public void willUseTheExternalStoragePublicDirectoryWhenItIsAvailable() {
// external storage is writeable
Mockito.when(Environment.getExternalStorageState()).thenReturn(Environment.MEDIA_MOUNTED);
// the external storage public directory is available
Mockito.when(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS)).thenReturn(existentDirectory);
String fileName = "someFileName";
String logFilePath = StorageUtils.getLogFilePath(fileName);
Assert.assertEquals(existentDirectory.getAbsolutePath() + File.separator + fileName, logFilePath);
}
@Test
public void willUseTheExternalStorageDirectoryWhenItIsAvailable() {
// external storage is writeable
Mockito.when(Environment.getExternalStorageState()).thenReturn(Environment.MEDIA_MOUNTED);
// the external storage public directory is not available
Mockito.when(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS)).thenReturn(nonExistentDirectory);
// the external storage directory is available
Mockito.when(Environment.getExternalStorageDirectory()).thenReturn(existentDirectory);
String fileName = "someFileName";
String logFilePath = StorageUtils.getLogFilePath(fileName);
Assert.assertEquals(existentDirectory.getAbsolutePath() + File.separator + fileName, logFilePath);
}
@Test
public void willUseTheDataDirectoryWhenExternalStorageIsNotWriteable() {
// external storage is not writeable
Mockito.when(Environment.getExternalStorageState()).thenReturn("not media mounted");
// the data directory is available
Mockito.when(Environment.getDataDirectory()).thenReturn(existentDirectory);
String fileName = "someFileName";
String logFilePath = StorageUtils.getLogFilePath(fileName);
Assert.assertEquals(existentDirectory.getAbsolutePath() + File.separator + fileName, logFilePath);
}
@Test
public void willUseTheDataDirectoryWhenNothingElseIsAvailable() {
// external storage is writeable
Mockito.when(Environment.getExternalStorageState()).thenReturn(Environment.MEDIA_MOUNTED);
// but neither of the external storage directories are available
Mockito.when(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS)).thenReturn(nonExistentDirectory);
Mockito.when(Environment.getExternalStorageDirectory()).thenReturn(nonExistentDirectory);
// so we must fall through to the data directory
Mockito.when(Environment.getDataDirectory()).thenReturn(existentDirectory);
String fileName = "someFileName";
String logFilePath = StorageUtils.getLogFilePath(fileName);
Assert.assertEquals(existentDirectory.getAbsolutePath() + File.separator + fileName, logFilePath);
}
@Test
public void doesSomethingWhenGivenANullFileName() {
// external storage is writeable
Mockito.when(Environment.getExternalStorageState()).thenReturn(Environment.MEDIA_MOUNTED);
// the external storage public directory is available
Mockito.when(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS)).thenReturn(existentDirectory);
String logFilePath = StorageUtils.getLogFilePath(null);
// the assertion here will depend on what your getAbsoluteFilePath() method does with a null file name!
Assert.assertEquals(existentDirectory.getAbsolutePath() + File.separator, logFilePath);
}
}

注：

• 这使用JUnit TemporaryFolder规则为断言创建(并在完成时丢弃)一个目录。这也可以使用模拟的File实例来实现

• OP没有包含getAbsoluteFilePath()的定义，所以我推测它是这样的：

  private static String getAbsoluteFilePath(File file, String fileName) {
  return file.getAbsolutePath() + File.separator + fileName;
  }
  

• 上面的例子并非详尽无遗，它旨在提供足够的，以便您了解它是如何工作的以及如何测试静态方法等