Java 如何通过jUnit测试内置扫描仪的方法？

以下是我的测试方法：

 @Test
public void Should_Print_All_Groups_With_Less_Or_Equals_Student_Count() throws ClassNotFoundException, IOException, SQLException {

    SchoolDao schoolDao = new SchoolDaoImplementation();
    Class.forName("org.postgresql.Driver");

    assertEquals(schoolDao.findAllGroupsWithLessOrEqualsStudentCount("testDb.properties"), "check");

}
}

下面是我要测试的方法：

 @Override
public HashMap<String, Integer> findAllGroupsWithLessOrEqualsStudentCount(String pathToDatabaseProperties) {

    ConnectionFactory connectionFactory = new ConnectionFactory();

    Scanner scanner = new Scanner(System.in);
    System.out.println("Please, enter minimum number of students in groups : ");
    int numberOfStudents = scanner.nextInt();
    System.out.println(main.drawGroupNamesAndNumberOfStudents(main.replaceGroupNumberToGroupName(main.countNumberOfStudentsInGroups(numberOfStudents, pathToDatabaseProperties), connectionFactory.connectToDatabase(pathToDatabaseProperties))));
    return main.replaceGroupNumberToGroupName(main.countNumberOfStudentsInGroups(numberOfStudents, pathToDatabaseProperties), connectionFactory.connectToDatabase(pathToDatabaseProperties));
}

@覆盖
公共HashMap findAllGroupsWithLessOrEqualsStudentCount（字符串路径数据库属性）{
ConnectionFactory ConnectionFactory=新的ConnectionFactory（）；
扫描仪=新的扫描仪（System.in）；
System.out.println（“请输入分组中的最小学生人数：”）；
int numberOfStudents=scanner.nextInt（）；
System.out.println（main.drawGroupNames和numberOfStudents（main.replaceGroupNumberToGroupName（main.countNumberOfStudentsInGroups（numberOfStudents，pathToDatabaseProperties），connectionFactory.connectToDatabase（pathToDatabaseProperties））；
返回main.replaceGroupNumberToGroupName（main.countNumberOfStudentsGroups（numberOfStudents，pathToDatabaseProperties），connectionFactory.connectToDatabase（pathToDatabaseProperties））；
}

但我不知道如何用内置扫描仪测试方法

因为现在我运行测试，程序正在加载，什么也不做

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所以，也许smb可以帮助您正确地编写测试。提前谢谢

理想情况下，您应该将用户输入作为单独的方法保存。双向帮助

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它将减少将来的冗余代码，您可以模拟该输入方法

使用当前解决方案，您不能模拟扫描仪，因为您在方法执行时正在创建新实例。这里可能有两种解决方案：

1.将扫描仪设为类字段：

public YourClass {
   private Scanner scanner = new Scanner(System.in);

@Override
public HashMap<String, Integer> findAllGroupsWithLessOrEqualsStudentCount(String pathToDatabaseProperties) {

    ConnectionFactory connectionFactory = new ConnectionFactory();

    System.out.println("Please, enter minimum number of students in groups : ");
    int numberOfStudents = scanner.nextInt();
    System.out.println(main.drawGroupNamesAndNumberOfStudents(main.replaceGroupNumberToGroupName(main.countNumberOfStudentsInGroups(numberOfStudents, pathToDatabaseProperties), connectionFactory.connectToDatabase(pathToDatabaseProperties))));
    return main.replaceGroupNumberToGroupName(main.countNumberOfStudentsInGroups(numberOfStudents, pathToDatabaseProperties), connectionFactory.connectToDatabase(pathToDatabaseProperties));
}

}

对扫描仪进行方法初始化：

公共课{

@Override
public HashMap<String, Integer> findAllGroupsWithLessOrEqualsStudentCount(String pathToDatabaseProperties) {

ConnectionFactory connectionFactory = new ConnectionFactory();

Scanner scanner = getScanner();
System.out.println("Please, enter minimum number of students in groups : ");
int numberOfStudents = scanner.nextInt();
System.out.println(main.drawGroupNamesAndNumberOfStudents(main.replaceGroupNumberToGroupName(main.countNumberOfStudentsInGroups(numberOfStudents, pathToDatabaseProperties), connectionFactory.connectToDatabase(pathToDatabaseProperties))));
return main.replaceGroupNumberToGroupName(main.countNumberOfStudentsInGroups(numberOfStudents, pathToDatabaseProperties), connectionFactory.connectToDatabase(pathToDatabaseProperties));

然后在类上使用@Spy并模拟此方法：

@Spy
private YourClass yourClass;
@Mock
private Scanner scanner;
...
when(yourClass.getScanner()).thenReturn(scanner);
when(scanner.nextInt()).thenReturn(number);

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您可以使用Powermockito模拟Scanner.java。类似问题：文档：

public Scanner getScanner() {
       return new Scanner(System.in);
    }
}

@Spy
private YourClass yourClass;
@Mock
private Scanner scanner;
...
when(yourClass.getScanner()).thenReturn(scanner);
when(scanner.nextInt()).thenReturn(number);