在集成测试中获取IHostingEnvironment

Question

我正在尝试为下面的类编写集成测试，但是我坚持在测试中获取IHostingEnvironment。我假设我应该能够从TestServer获得IHostingEnvironment，但没有骰子。我缺少基本的东西吗？比集成测试更适合单元测试吗？

实际课程

public class PasswordResetMessage : IMessage
    {
        private readonly PasswordReset passwordReset;
        private readonly IHostingEnvironment iHostingEnvironment;
        public PasswordResetMessage(IHostingEnvironment iHostingEnvironment, PasswordReset passwordReset)
        {
            this.passwordReset = passwordReset;
            this.iHostingEnvironment=iHostingEnvironment;
        }
        public string Get()
        {
            var stringBuilder = new StringBuilder();
            var pathToFile = Path.Combine(iHostingEnvironment.ContentRootPath, "EmailTemplates", "password_reset.txt");
            using (var streamReader = File.OpenText(pathToFile))
            {
                stringBuilder.Append(streamReader.ReadToEnd());
            }
            return stringBuilder.Replace("{{ActionURL}}", passwordReset.ActionURL).ToString();
        }
    }

集成测试：

public class PasswordResetMessageTest
    {
        private PasswordResetMessage passwordResetMessage;
        private readonly TestServer testServer;
        public PasswordResetMessageTest()
        {
            testServer = new TestServer(new WebHostBuilder().UseStartup<Startup>());
            passwordResetMessage = new PasswordResetMessage(**<IDon'tKnowWhatToPassHere>**, new PasswordReset());
        }

        [Fact]
        public void Get()
        {
            var message=passwordResetMessage.Get();
            Assert.Contains(message, "");
        }
    }