Lumina

Manuals / API Testing / Ch 3

A · HTTP FoundationsBeginner60 min read

3. Postman collections & environments

API Testing · 44 pages source format

Postman is the industry default for API exploration. Collections, environments, variables, and test scripts — organized like a real QA team.

What you'll learn

  • Collections and folders
  • Environment variables
  • Pre-request scripts
  • Tests tab assertions

Build a collection

Folder by resource: /users, /posts. Name requests as verbs: Get User, Create Post. Variables: {{baseUrl}}, {{userId}}.

Do this now

Create JSONPlaceholder collection with 8 requests across users and posts.

Clear?

Environment setup

Dev/staging/prod environments swap baseUrl without duplicating requests.

Do this now

Create environments local and staging (same baseUrl for lab). Switch and re-run.

Clear?

Tests tab assertions

pm.test("status is 200", () => pm.response.to.have.status(200)); pm.expect(json.id).to.eql(1);

pm.test("Status is 200", function () {
  pm.response.to.have.status(200);
});
pm.test("User has email", function () {
  var json = pm.response.json();
  pm.expect(json.email).to.include("@");
});

Do this now

Add 3 tests per request on GET user: status, content-type, body fields.

Clear?

Chain variables

Create post → save id from response → use in GET /posts/{{postId}}.

Do this now

POST new post, parse pm.response.json().id into pm.environment.set("postId", id).

Clear?

Checklist