postman断言是JavaScript语言编写的，在postman客户端的test区域编写即可，
断言会在请求返回之后，运行，并根据断言的passfail情况体现在最终测试结果中。
断言如下：
1.设置环境变量--Setting an environment variable
postman.setEnvironmentVariable("key", "value");
2.设置全局变量--Set a global variable
postman.setGlobalVariable("key", "value");
3.检查响应中包含string--Check if response body contains a string
tests["Body matches string"] = responseBody.has("string_you_want_to_search");
4.转化XML格式的响应成JSON对象---Convert XML body to a JSON object
var jsonObject = xml2Json(responseBody);
5.检查响应body中等于指定string--Check if response body is equal to a string
tests["Body is correct"] = responseBody === "response_body_string";6.检查JSON某字段值--Check for a JSON value
var data = JSON.parse(responseBody);
tests["json test"] = data.showDes === "0001";
针对JSON数据：tests["aaa"] = data.books[0].pubdate === "1972年4月";
7.检查Content-Type是否包含在header返回（大小写不敏感）--Content-Type is
present (Case-insensitive checking)
tests["Content-Type is present"] = postman.getResponseHeader("Content-Type");
//Note: the getResponseHeader() method returns the header value, if it exists.
8.检查Content-Type是否包含在header返回（大小写敏感）--Content-Type is
present (Case-sensitive)
tests["Content-Type is present"] = responseHeaders.hasOwnProperty("Content-
Type");
9.检查请求耗时时间小于200ms--Response time is less than 200ms
tests["Response time is less than 200ms"] = responseTime < 200;
10.检查Status code为200--Status code is 200
tests["Status code is 200"] = responseCode.code === 200;
11.检查Code name包含指定string--Code name contains a string
tests["Status code name has string"] = responseCode.name.has("Created");
12.检查成功post的请求status code--Succesful