一文带你了解Mock 技术体系

简介

为什么要学习 Mock

• 提高测试深度
• 提高测试效率
• 降低成本

1. 测试股票软件，模拟当天股票全部上涨
2. 测试股票软件，模拟当天股票全部下跌
3. 测试股票软件，模拟部分股票涨幅10%

Test Double 测试替身

• Dummy 占位对象 对象被传递但从未实际使用过。通常它们仅用于填充参数列表。
• Fake 假对象 对象实际上有工作实现，但通常采取一些捷径，这使得它们不适合生产（内存数据库就是一个很好的例子）。
• Stubs 桩对象 为测试期间调用提供预设答案，通常根本不响应任何超出测试程序的内容。
• Spies 间谍对象 它们还根据调用方式记录一些信息。其中一种形式可能是电子邮件服务，它记录发送了多少消息。
• Mocks 模拟对象 是我们在这里谈论的：预先编程的对象，这些期望形成了它们期望接收的调用的规范。

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测试替身关键概念的区别

一个真实的技术架构例子

• dummy 只要端口开着就行
• fake 内存数据库
• spy UI 界面后端请求记录
• stub 假的登录后端服务
• hook 新用户判断方法修改
• proxy 代理转发机制
• mock 模拟对象

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Fake 假对象 定义

Fake objects actually have working implementations, but usually take some shortcut which makes them not suitable for production (an InMemoryTestDatabase is a good example).

假对象实际上有工作实现，但通常采取一些捷径，这使得它们不适合生产（纯内存数据库就是一个很好的例子）。

Fake 应⽤场景

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Stub 桩定义

Stubs provide canned answers to calls made during the test, usually not responding at all to anything outside what’s programmed in for the test.

为测试期间调用提供预设答案，通常根本不响应任何超出测试程序的内容。

Stub 应⽤场景 Swagger

Setup Stub Server

java -jar moco-runner-1.2.0-standalone.jar http -p 12345 -c foo.json

{
  "request" :
    {
      "uri" : "/foo",
      "queries" :
        {
          "param" : "blah"
        }
    },
  "response" :
    {
      "text" : "bar"
    }
}

Mock 模拟对象定义

Mocks are pre-programmed with expectations which form a specification of the calls they are expected to receive. They can throw an exception if they receive a call they don’t expect and are checked during verification to ensure they got all the calls they were expecting.

模拟预编程了期望，这些期望形成了他们期望接收的调用的规范。如果他们收到了他们不期望的调用，他们可以抛出异常，并在验证过程中进行检查以确保他们得到了他们期望的所有调用。

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Mock 两种应用场景

• mock on stub：按需返回期望数据
• mock on proxy：按需返回真实数据的修改副本

常⽤的 Mock 工具

• Charles 测试工程师常用
• BurpSuite 黑客常用
• Fiddler 只能 Windows 上使用
• Nginx 服务器反向代理与修改
• Mitmproxy 代理工具 可编程
• Wiremock 代理工具 可编程

mitmproxy

mitmproxy is a set of tools that provide an interactive, SSL/TLS-capable intercepting proxy for HTTP/1, HTTP/2, and WebSockets.

mitmproxy mock on proxy

python3 -m http.server
mitmdump -p 8001  -m reverse:127.0.0.1:8000 --flow-detail 4 -B '/~bs .*Directory.*/Directory/ceshiren.com mock'

mitmproxy 强大的插件机制 Addons

• dns
• tcp
• cert
• http/https
• websocket

adb mock 案例

import sys

from mitmproxy import ctx
from mitmproxy import tcp
from mitmproxy.utils import strutils
from mitmproxy.tools.main import mitmdump


def tcp_message(flow: tcp.TCPFlow):
    message = flow.messages[-1]
    old_content = message.content
    message.content = old_content.replace(
        b":0;localabstract:webview_devtools_remote_",
        b":   0;localabstract:xweb_devtools_remote_"
    )

    ctx.log.info(
        "[tcp_message{}] from {} to {}:\n{}".format(
            " (modified)" if message.content != old_content else "",
            "client" if message.from_client else "server",
            "server" if message.from_client else "client",
            strutils.bytes_to_escaped_str(message.content))
    )


if __name__ == '__main__':
    sys.argv = ["", "-p", "5038", "--rawtcp", "--mode", "reverse:http://localhost:5037/", "-s", sys.argv[0], "-vv"]
    mitmdump()

WireMock

The flexible tool for building mock APIs.
Create stable development environments, isolate yourself from flakey 3rd parties and simulate APIs that don’t exist yet.

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wiremock stub

java -jar wiremock-jre8-standalone-2.33.2.jar

{  "request": {    "method": "GET",    "url": "/wiremock"  },
  "response": {    "status": 200,    "body": "Easy!"  }}

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mock on stub

@Test
public void exactUrlOnly() {
    stubFor(get(urlEqualTo("/some/thing"))
            .willReturn(aResponse()
                .withHeader("Content-Type", "text/plain")
                .withBody("Hello world!")));

    assertThat(testClient.get("/some/thing").statusCode(), is(200));
    assertThat(testClient.get("/some/thing/else").statusCode(), is(404));
}

mock on proxy

wm.stubFor(get(urlPathEqualTo("/templated"))
  .willReturn(aResponse()
      .proxiedFrom("$!request.headers.X-WM-Proxy-Url")
      .withTransformers("response-template")));

public class ExampleTransformer extends ResponseDefinitionTransformer {


    @Override
    public ResponseDefinition transform(Request request, ResponseDefinition responseDefinition, FileSource files, Parameters parameters) {
        String content=responseDefinition.getTextBody().replace("霍格沃兹", "mock");
        System.out.println(responseDefinition.getTextBody());
        System.out.println(content);
        return new ResponseDefinitionBuilder()
                .withHeader("MyHeader", "Transformed")
                .withStatus(200)
                .withBody(content)
                .build();
    }


    @Override
    public String getName() {
        return "hogwarts_mock";
    }
}

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总结

• 了解测试替身的实现方式，统一沟通概念
• 了解 Mock 的常见应用场景