Android Mockito到mock类的最后一个字段

我试图模仿班上最后一场比赛

data class Student(
    val id: Int,
    val name: String,
    val marks: Marks
)

data class Marks(
    val subject1: String
)

这是我的测试课

class StudentTest {

    @Test
    fun testStudentMarks() {
        val student = mock(Student::class.java)
        assertNotNull(student.id)
        assertNotNull(student.marks)
    }

}

在运行测试时，它通过student.id，但在student.marks上失败，错误如下

junit.framework.AssertionFailedError
    at junit.framework.Assert.fail(Assert.java:55)
    at junit.framework.Assert.assertTrue(Assert.java:22)
    at junit.framework.Assert.assertNotNull(Assert.java:256)
    at junit.framework.Assert.assertNotNull(Assert.java:248)
    at com.example.mockitotest.StudentTest.testStudentMarks(StudentTest.kt:16)

---

既然它是一个

Kotlin

类，那么如何模拟标记字段呢

Mockito.when(student.id).thenReturn(0)

或

val m = Mockito.mock(Marks::class.java)
Mockito.when(student.marks).thenReturn(m)