Android Studio 3.4

override fun loginUserPost(username: String, password: String, uniqueIdentifier: String, deviceToken: String, apiToken: String) : Single<LoginResponse> {
            val loginRequestEntity = LoginRequestEntity(username, password, uniqueIdentifier, deviceToken)
            return loginAPIService.loginUserPost(loginRequestEntity, apiToken)
                .map {
                    loginResponseDomainMapper.map(it)
                }
    }

@Test
    fun `should return LoginResponse`() {
        val loginRequestEntity = LoginRequestEntity("username", "password", "uniqueidentifier", "devicetoken")
        val loginResponse = LoginResponse("token", createUser(), emptyList(), emptyList())
        val loginResponseEntity = LoginResponseEntity("token", createUserEntity(), emptyList(), emptyList())

        whenever(loginAPIService.loginUserPost(loginRequestEntity, "apitoken")).thenReturn(Single.just(loginResponseEntity))
        whenever(loginAPIService.loginUserPost(loginRequestEntity, "apitoken").map {
            loginResponseDomainMapper.map(it)
        }).thenReturn(Single.just(loginResponse))

        loginServiceImp.loginUserPost("username", "password", "uniqueidentifier", "devicetoken", "apitoken")

        verify(loginAPIService).loginUserPost(loginRequestEntity, "apitoken")
    }

    private fun createUser() =
        User(
            "id",
            "email",
            "firstname",
            "lastname",
            "phone",
            "address",
            "dob",
            "customer",
            listOf("enterpriseids"),
            listOf("vendorids"))

    private fun createUserEntity() =
        UserEntity(
            "id",
            "email",
            "firstname",
            "lastname",
            "phone",
            "address",
            "dob",
            "customer",
            listOf("enterpriseids"),
            listOf("vendorids"))
}