我已经将thymeleaf和spring test添加到我的spring boot项目中：

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>

然后我创建了一个简单的服务来执行渲染：

package com.myorg.myproject.service

import org.springframework.beans.factory.annotation.Autowired
import org.springframework.mock.web.MockHttpServletRequest
import org.springframework.mock.web.MockHttpServletResponse
import org.springframework.stereotype.Service
import org.springframework.web.servlet.ViewResolver
import java.util.*

@Service
class HtmlRenderer {

    @Autowired
    private lateinit var viewResolver: ViewResolver

    fun render(): String {

        val resolvedView = viewResolver.resolveViewName("activity", Locale.US)
            ?: throw Exception("Unable to find view.")

        val mockRequest = MockHttpServletRequest()
        mockRequest.contentType = "text/html"
        val mockResponse = MockHttpServletResponse()
        resolvedView.render(null, mockRequest, mockResponse)

        return mockResponse.contentAsString
    }
}

我在创建了一个模板 resources/templates/activity.html . 但是当我们排队的时候 mockResponse.contentAsString 如果运行，则返回空字符串。
我是否遗漏了将模板呈现为字符串的任何特定步骤？