Writing Tests in Postman

In previous blog post, we saw how to use BDD format for writing test cases in postman. Most important part of writing tests in postman is understanding various features available. Let us explore various options available . The examples specified in postman documentation, have lot of information about how to setup postman bdd, use chai http assertions, create custom assertions and use before and after hooks. Please import them into postman and try that by yourself to familiarise with postman BDD. Below is only few examples from them.

Postman BDD makes use of Chai Assertion Library and Chai-Http. We have access to both libray and postman scripting environment for writing test cases. Chai has two types of assertion styles.

• Expect/should for BDD
• Assert for TDD

Both styles support chainable language to construct assertions. We can use both of them to write postman test assertions. If you need details of all chainable constructs, please refer to their documentation. Major ones which we may use in postman tests are

• Chains

    to
    be
    been
    is
    that
    which
    and
    has
    have
    with
    at
    of
    same
    but
    does
  

• Not - Negates all conditions

• any -
• all -
• inlcude
• OK
• true
• false
• null
• undefined
• exist
• empty
• match(re[, msg])

Chai-Http module provide various assertions. Read through their documentation here to know details. Below are main commands at our disposal for validation .

• .status(code)
• .header (key[, value])
• .headers
• .ip
• .json / .text / .html
• .redirect
• .param
• .cookie

Postman bdd provide response object on which we do most of assertions. It will have all information like response.text, response.body, response.status, response.ok , response.error. Postman BDD will automatically parse JSON and XML responses and hence there is no need to call JSON.parse() or xml2json(). response.text will have unparsed content. It also have automatic error handling , which will allow to continue with other test even if something fails.

Examples for various assertions done on response object are below

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\\Verifying Header information
expect(response).to.have.status(500);
expect(response).to.have.header('x-api-key');
expect(response).to.have.header('content-type', 'text/plain');
expect(request).to.have.header('content-type', /^text/);
expect(response).to.have.headers;
expect('127.0.0.1').to.be.an.ip;

\\Verifying Response body
expect(response).to.be.json;
expect(response).to.be.html;
expect(response).to.be.text;

response.should.have.status(200); 
response.body.should.not.be.empty;
response.ok.should.be.true;            // sucess with code 2XX
response.error.should.be.true; //failures

\\Verifying request
expect(req).to.have.param('orderby', 'date');
expect(req).to.not.have.param('orderby');
expect(req).to.have.cookie('session_id', '1234');
expect(req).to.not.have.cookie('PHPSESSID');

If we use above assertions in proper BDD format, it will look like below

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eval(globals.postmanBDD);
describe('Example for Blog using SHOULD', function(){
   it("Tests using SHOULD", function() {
      response.should.have.status(200); 
      response.should.not.be.empty;
      response.should.have.header('content-type', 'application/json; charset=utf-8');
      response.type.should.equal('application/json');
      
      var user = response.body.results[0];
      user.name.should.be.an('object');
      user.name.should.have.property('first').and.not.empty;
      //user.name.should.have.property('first','david');
      user.should.have.property('gender','male');
   
   
   }) 
})
describe('Example for Blog using Expect', function(){
   it("Tests using EXPECT", function() {
      expect(response).to.have.status(200);
      expect(response).not.empty;
      expect(response).to.be.json;
      expect(response).to.have.header('content-type', 'application/json; charset=utf-8');
   }) 
})

it('should contain the un-parsed JSON text', () => {
    response.text.should.be.a('string').with.length.above(50);
    response.text.should.contain('"results":[');
});