c# - 使用 NUnit 和 C# 进行异步单元测试

Question

我创建了以下方法，它只是从 HTTP 服务器检索数据没什么特别的，但它是一个异步方法。

public async Task<string> GetStringFromConsul(string key)
    {
        string s = "";

        // attempts to get a string from Consul
        try
        {
            //async method to get the response
            HttpResponseMessage response = await this.http.GetAsync(apiPrefix + key);

            //if it responds successfully
            if (response.IsSuccessStatusCode)
            {
                //parse out a string and decode said string
                s = await response.Content.ReadAsStringAsync();
                var obj = JsonConvert.DeserializeObject<List<consulValue>>(s);
                s = Encoding.UTF8.GetString(Convert.FromBase64String(obj[0].value));
            }
            else
            {
                s = requestErrorCodePrefix + response.StatusCode + ">";
            }
        } 
        catch(Exception e)
        {
            //need to do something with the exception
            s = requestExceptionPrefix + e.ToString() + ">";
        }

        return s;
    }

然后在测试中我像正常执行时一样调用代码:

[Test]
    public async Task GetStringFromConsulTest()
    {
        ConsulConfiguration cc = new ConsulConfiguration();

        string a = cc.GetStringFromConsul("").GetAwaiter().GetResult();
        Assert.AreEqual(a, "");
    }

但是我得到了这样的异常，而不是任何类型的字符串:

Message:   Expected string length 514 but was 0. Strings differ at index 0.
  Expected: "<Request Exception: System.Threading.Tasks.TaskCanceledExcept..."
  But was:  <string.Empty>

我环顾四周，找到了一些关于此的教程并尝试了但无济于事。如果有人能指出我正确的方向，我将不胜感激，我是 C# 单元测试的新手。

Answer 1

我是一个很好的错误消息的坚持者，所以我首先将断言更改为

Assert.AreEqual("", a);

因为第一个 参数是您的期望值。现在它将失败

Message:   Expected string length 0 but was 514. Strings differ at index 0.
  Expected:  <string.Empty>
   But was: "<Request Exception: System.Threading.Tasks.TaskCanceledExcept..."

...仍然是一个失败，但一个更明智的消息。

接下来，按照 M Hassan 的建议，为您的异步方法调用添加一个 await。