发出最小起订量 HttpResponseMessage

问：

我有以下方法：

public async Task<SecurityRoleDeleteResult> DeleteSecurityRoleByRoleId(int securityRoleId)
{
    string url = $"{_housingDataSecurityConfiguration.HousingDataSecurityWebApiUrl}SecurityRoles/Delete";

    HttpResponseMessage message = _apiClientService.Post(url, securityRoleId);

    if (message.StatusCode == HttpStatusCode.InternalServerError)
    {
        return SecurityRoleDeleteResult.ErrorOccurred;
    }

    int intResult = 0;
    var apiResult = await message.Content.ReadAsStringAsync();
    if (int.TryParse(apiResult, out intResult))
    {
        return (SecurityRoleDeleteResult)intResult;
    }
    else
    {
        return SecurityRoleDeleteResult.ErrorOccurred;
    }
}

我现在正在尝试为它编写一个单元测试，到目前为止已经：

[Test]
public async Task DeleteSecurityRoleByRoleId()
{
    _mockApiClientService.Setup(a => a.Post(It.IsAny<string>(), It.IsAny<int>()))
        .Returns(new HttpResponseMessage {StatusCode = HttpStatusCode.OK});

    SecurityRoleDeleteResult result = await _securityRoleService.DeleteSecurityRoleByRoleId(It.IsAny<int>());

    Assert.AreEqual(SecurityRoleDeleteResult.Success, result);
}

这里的问题是，在我尝试将 message.content 设置为 null 的方法中运行测试时，因为在这种情况下，我只是在模拟所以崩溃。_securityRoleService.DeleteSecurityRoleByRoleIdvar apiResult

我怎样才能模拟出来，以便我的测试能够正常工作？