使用Dart嘲笑HTTP响应 [英] Mocking HTTP response with Dart

问题描述

我一直在开发一个新的API包装器，不想在每次运行单元测试时调用API。因此，如这里所述，我嘲笑它。

I have been working on a new API wrapper and don't want to be calling the API every time my unit tests run. So as described here, I'm mocking it.

我最初认为我嘲笑它的方式有问题，但似乎问题出在其他地方。

I initially thought there was something wrong with the way I'm mocking it, but it seems the problem is elsewhere.

我想要完成的事很简单。当我的单元测试运行时，我想返回一个值，好像我已经从外部API中获取信息，我正在整合。

What I'm trying to accomplish is very simple. When my unit test run, I would like to return a value as if I had gone out to get the information from the external API I'm integrating with.

我初始化我的类用http.Client作为可选参数，所以我可以传递它在单元测试运行时这样：

I initialise my class with http.Client as an optional parameter, so I can pass it in when the unit tests run as such:

SampleClass(String arg1, String arg2, [http.Client httpClient = null]) {
    this._arg1 = arg1;
    this._arg2 = arg2;
    _httpClient = (httpClient == null) ? http.Request : httpClient;
}

Future apiRequest(String resource, [Map<String, String> body]) {
    var url = buildBaseUrl(resource).toString();
    var request = new http.Request('POST', Uri.parse(url));
    request.bodyFields = body;
    return this._httpClient.send(request).then((response) => response.stream.bytesToString().then((value) => value.toString()));
}

在我的单元测试中，我创建了以下mock类：

In my unit test I have created the following mock class:

class HttpClientMock extends Mock implements http.Client {
  noSuchMethod(i) => super.noSuchMethod(i);
}

class HttpResponseMock extends Mock implements http.Response {
    noSuchMethod(i) => super.noSuchMethod(i);
}

在我的单元测试检查响应我做以下：

And in my unit test to check the response I'm doing the following:

test("Send SMS errors with wrong account", () {
    var mockHttpClient = new HttpClientMock()
                             ..when(callsTo('send')).alwaysReturn(message401);
    var sample = new SampleClass(_arg1, _arg2, mockHttpClient);
    future = sample.apiRequest(...parameters here...).then((value) => value.toString());
    expect(future.then((value) => JSON.decode(value)), completion(equals(JSON.decode(message401))));
});

所以，你可以看到，我试图让它调用send返回 message401 ，这只是一个 JSON 字符串。

So, as you can see, I am trying to make it so calling send returns message401, which is just a JSON string.

，因为 message401 是一个字符串，并且因为我的代码试图使用它作为一个未来，我总是得到错误：

This is not happening, since message401 is a string, and because my code tries to use it as a Future, I always get the error:

顶级未捕获错误：类'String'没有实例方法
'then'。

Top-level uncaught error: Class 'String' has no instance method 'then'.

我完全明白为什么我得到这个错误，但不知道如何解决。

I totally understand why I'm getting this error, but have no idea about how to go around it.

任何帮助。

Any help appreciated.

推荐答案

http 包有测试库与 MockClient 。

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