Postman ও Insomnia — API Testing Tools

API Testing Tool কেন দরকার?

Backend developer হিসেবে API বানানোর পর সেটা test করতে হয়। Browser-এ শুধু GET request করা যায় — POST, PUT, DELETE করতে হলে tool দরকার।

Browser:
✅ GET /api/users     → কাজ করে
❌ POST /api/users    → করা যায় না (form ছাড়া)
❌ PUT /api/users/42  → করা যায় না
❌ DELETE            → করা যায় না
❌ Custom headers    → দেওয়া যায় না

Postman/Insomnia:
✅ GET, POST, PUT, PATCH, DELETE → সব method
✅ Custom headers → Authorization, Content-Type
✅ Request body → JSON, form-data, file upload
✅ Environment variables → dev/staging/prod switch
✅ Automated testing → response check
✅ Collection → requests organize

cURL দিয়েও করা যায়:
curl -X POST https://api.example.com/users \
  -H "Authorization: Bearer token123" \
  -H "Content-Type: application/json" \
  -d '{"name":"Ripon","email":"ripon@example.com"}'

কিন্তু:
❌ মনে রাখা কঠিন
❌ Response সুন্দরভাবে দেখায় না
❌ Save/reuse করা যায় না
❌ Team-এ share করা কঠিন

Postman/Insomnia GUI দিয়ে এসব সহজ!

Postman

সবচেয়ে জনপ্রিয় API testing tool। ২৫ মিলিয়ন+ developer ব্যবহার করে।

Request পাঠানো (Basic)

1. Method select করো: GET / POST / PUT / PATCH / DELETE
2. URL লেখো: https://api.example.com/users
3. Headers যোগ করো (optional):
   Authorization: Bearer eyJhbG...
   Content-Type: application/json
4. Body যোগ করো (POST/PUT/PATCH):
   { "name": "Ripon", "email": "ripon@example.com" }
5. Send বাটন চাপো!
6. Response দেখো: Status, Body, Headers, Time

Response panel-এ দেখা যায়:

Status:  200 OK
Time:    145 ms
Size:    2.3 KB

Body (Pretty):
{
  "status": "success",
  "data": {
    "id": 42,
    "name": "Ripon",
    "email": "ripon@example.com"
  }
}

Headers:
Content-Type: application/json
X-RateLimit-Remaining: 95

Collections — Requests Organize করা

Related requests একটা folder-এ group করা:

📁 User Management API
├── 📁 Auth
│   ├── POST /auth/register
│   ├── POST /auth/login
│   └── POST /auth/refresh-token
├── 📁 Users
│   ├── GET /users
│   ├── GET /users/:id
│   ├── POST /users
│   ├── PATCH /users/:id
│   └── DELETE /users/:id
├── 📁 Posts
│   ├── GET /posts
│   ├── POST /posts
│   └── GET /posts/:id/comments
└── 📁 Admin
    ├── GET /admin/dashboard
    └── GET /admin/users?role=admin

Collection export করে team-এ share করা যায় (JSON file)।

Environment Variables

Development, staging, production — আলাদা URL/token ব্যবহার করতে:

Environment: Development
{
  "baseUrl": "http://localhost:3000/api/v1",
  "token": "dev-token-abc123"
}

Environment: Staging
{
  "baseUrl": "https://staging-api.example.com/v1",
  "token": "staging-token-xyz789"
}

Environment: Production
{
  "baseUrl": "https://api.example.com/v1",
  "token": "prod-token-secure456"
}

Request-এ variable ব্যবহার:

URL:    {{baseUrl}}/users
Header: Authorization: Bearer {{token}}

Environment switch করলে URL আর token automatic বদলে যায়!

Variables-এর ধরন:

Global Variables:     সব collection-এ কাজ করে
Collection Variables: শুধু ঐ collection-এ
Environment Variables: selected environment অনুযায়ী
Local Variables:      শুধু ঐ request-এ

Priority: Local > Environment > Collection > Global

Dynamic Variables

Postman-এর built-in dynamic values:

{{$randomFullName}}      → "Ripon Ahmed"
{{$randomEmail}}         → "ripon42@example.com"
{{$randomUUID}}          → "6929bb52-3ab2-448a-9796-d6480ecad36b"
{{$randomInt}}           → 742
{{$randomBoolean}}       → true
{{$timestamp}}           → 1708271400 (Unix timestamp)
{{$isoTimestamp}}        → "2026-02-18T14:30:00.000Z"

json

POST /api/users
{
  "name": "{{$randomFullName}}",
  "email": "{{$randomEmail}}",
  "age": {{$randomInt}}
}
→ প্রতিবার আলাদা random data দিয়ে test!

Pre-request Scripts

Request পাঠানোর আগে JavaScript code চালানো:

javascript

// Login করে token নিয়ে variable-এ set করো
const loginUrl = pm.environment.get("baseUrl") + "/auth/login";

pm.sendRequest({
    url: loginUrl,
    method: 'POST',
    header: { 'Content-Type': 'application/json' },
    body: {
        mode: 'raw',
        raw: JSON.stringify({
            email: "ripon@example.com",
            password: "secret123"
        })
    }
}, (err, res) => {
    const token = res.json().token;
    pm.environment.set("token", token);
});

javascript

// Timestamp generate করে variable-এ রাখো
const timestamp = new Date().toISOString();
pm.variables.set("currentTime", timestamp);

// Random ID generate
pm.variables.set("randomId", Math.floor(Math.random() * 1000));

Test Scripts — Response Verify করা

Request-এর পরে response check করা:

javascript

// Status code check
pm.test("Status code is 200", () => {
    pm.response.to.have.status(200);
});

// Response time check
pm.test("Response time < 500ms", () => {
    pm.expect(pm.response.responseTime).to.be.below(500);
});

// Body content check
pm.test("Response has correct structure", () => {
    const json = pm.response.json();
    pm.expect(json.status).to.eql("success");
    pm.expect(json.data).to.be.an("array");
    pm.expect(json.data.length).to.be.greaterThan(0);
});

// Header check
pm.test("Content-Type is JSON", () => {
    pm.response.to.have.header("Content-Type", "application/json; charset=utf-8");
});

// Save response data for next request
pm.test("Save user ID", () => {
    const json = pm.response.json();
    pm.environment.set("userId", json.data.id);
});

Test Results panel:
✅ Status code is 200
✅ Response time < 500ms
✅ Response has correct structure
✅ Content-Type is JSON
✅ Save user ID

5/5 tests passed!

Collection Runner — Bulk Test

Collection-এর সব request একসাথে চালানো:

📁 User API Collection
  1. POST /auth/login          ← token পায়
  2. GET /users                ← token ব্যবহার করে
  3. POST /users               ← নতুন user তৈরি
  4. GET /users/{{userId}}     ← সদ্য তৈরি user দেখায়
  5. PATCH /users/{{userId}}   ← update করে
  6. DELETE /users/{{userId}}  ← delete করে

Run Collection:
✅ Login — 200 OK (token saved)
✅ Get Users — 200 OK (array returned)
✅ Create User — 201 Created (userId saved)
✅ Get User — 200 OK (correct user)
✅ Update User — 200 OK (updated)
✅ Delete User — 204 No Content

6/6 passed! পুরো CRUD flow test হয়ে গেল!

Data file দিয়ে multiple iteration:

csv

name,email,role
Ripon,ripon@example.com,admin
Karim,karim@example.com,user
Fatema,fatema@example.com,moderator

Run with data file:
Iteration 1: name=Ripon, email=ripon@... → ✅
Iteration 2: name=Karim, email=karim@... → ✅
Iteration 3: name=Fatema, email=fatema@... → ✅

3 iterations × 6 requests = 18 requests, all passed!

Chain Requests — একটার output পরেরটার input

Request 1: POST /auth/login
  Body: { "email": "ripon@example.com", "password": "secret" }
  Test Script:
    const token = pm.response.json().token;
    pm.environment.set("authToken", token);      ← token save

Request 2: POST /users
  Header: Authorization: Bearer {{authToken}}    ← token ব্যবহার
  Body: { "name": "New User" }
  Test Script:
    const userId = pm.response.json().data.id;
    pm.environment.set("newUserId", userId);     ← userId save

Request 3: GET /users/{{newUserId}}              ← userId ব্যবহার
  Header: Authorization: Bearer {{authToken}}

→ প্রতিটি request আগেরটার data ব্যবহার করে!

Mock Server

Backend ready না হলেও frontend team কাজ শুরু করতে পারে:

Mock Server setup:
1. Collection থেকে Mock Server তৈরি করো
2. প্রতিটি request-এ example response দাও
3. Mock URL পাও: https://mock-server-id.mock.pstmn.io

Frontend team:
fetch('https://mock-server-id.mock.pstmn.io/api/users')
→ Example response পায় (আসল backend ছাড়াই!)

Backend ready হলে:
URL বদলে দাও → https://api.example.com/api/users
→ আসল data আসতে শুরু করে

Newman — CLI Runner

Postman collections command line থেকে চালানো (CI/CD-তে):

bash

# Install
npm install -g newman

# Run collection
newman run my-collection.json -e development.json

# Run with reporters
newman run my-collection.json \
  -e development.json \
  --reporters cli,html \
  --reporter-html-export report.html

CI/CD Pipeline:
GitHub Actions / Jenkins:
1. Code deploy
2. newman run api-tests.json    ← API test চালাও
3. All passed? → Deploy to production
4. Failed? → Block deployment ❌

Insomnia

Postman-এর lightweight alternative। Open-source friendly, clean UI।

Insomnia Features

✅ সব HTTP method support
✅ GraphQL built-in support (Postman-এর চেয়ে ভালো)
✅ Environment variables
✅ Plugin system
✅ gRPC support
✅ WebSocket support
✅ Code generation (cURL, Python, JS, Go...)
✅ Git sync (spec file version control)
✅ OpenAPI import/export
✅ Template tags (dynamic values)

Insomnia-র বিশেষত্ব — GraphQL

Insomnia-তে GraphQL query লেখা অনেক সহজ:

1. URL: https://api.example.com/graphql
2. Body type: GraphQL
3. Query:
   query {
     user(id: 42) {
       name
       email
       posts {
         title
       }
     }
   }

→ Auto-complete! Schema থেকে suggestion দেয়
→ Query validation
→ Variables panel আলাদা

Template Tags

Insomnia-র dynamic values:

{% timestamp %}           → Unix timestamp
{% uuid %}                → Random UUID
{% now 'YYYY-MM-DD' %}   → "2026-02-18"
{% response 'body', 'req_login', '$.token' %}
    → আগের request-এর response থেকে value নেয়!

Postman vs Insomnia তুলনা

Feature	Postman	Insomnia
UI	Feature-rich, complex	Clean, simple
Speed	ভারী (Electron)	হালকা
GraphQL	⚠️ Basic	✅ Excellent
gRPC	❌	✅
WebSocket	✅	✅
Collections	✅ Advanced	✅ Basic
Test Scripts	✅ JavaScript	❌ নেই
Collection Runner	✅	❌ নেই
Mock Server	✅ Built-in	❌ নেই
Newman (CLI)	✅	❌ (Inso CLI আছে)
Team Collaboration	✅ Cloud sync	⚠️ Git sync
Environment	✅	✅
Code Gen	✅	✅
OpenAPI	✅ Import	✅ Import/Design
Price	Freemium	Freemium
Open Source	❌	⚠️ Core only

কোনটা বেছে নেবে:

Postman ব্যবহার করো যদি:
✅ Team collaboration দরকার
✅ Automated testing (test scripts, runner)
✅ CI/CD integration (Newman)
✅ Mock server দরকার
✅ বড় team, enterprise

Insomnia ব্যবহার করো যদি:
✅ GraphQL primary
✅ Lightweight tool চাই
✅ gRPC support দরকার
✅ Clean, simple UI prefer করো
✅ Solo developer / ছোট team

অন্যান্য API Testing Tools

Tool	বৈশিষ্ট্য	কখন ব্যবহার
cURL	Command line, সব জায়গায় আছে	Quick test, scripting
HTTPie	cURL-এর modern alternative	Developer-friendly CLI
Thunder Client	VS Code extension	IDE ছাড়তে চাই না
REST Client	VS Code extension (.http files)	Code-এর পাশে test
Bruno	Open-source, Git-friendly	Postman alternative
Hoppscotch	Browser-based, open-source	No install, quick test

Thunder Client (VS Code)

VS Code-এর ভেতরেই API test:
- Extension install করো
- Sidebar-এ Thunder Client icon
- New Request → URL → Send
- Collections, Environment support

সুবিধা: IDE switch করতে হয় না!

REST Client (VS Code)

.http file লিখে সরাসরি VS Code থেকে request পাঠানো:

http

### Login
POST http://localhost:3000/api/auth/login
Content-Type: application/json

{
  "email": "ripon@example.com",
  "password": "secret123"
}

### Get Users
GET http://localhost:3000/api/users
Authorization: Bearer {{token}}

### Create User
POST http://localhost:3000/api/users
Content-Type: application/json
Authorization: Bearer {{token}}

{
  "name": "New User",
  "email": "new@example.com"
}

.http file Git-এ commit করা যায় — team-এ share হয়ে যায়!

HTTPie (CLI)

cURL-এর চেয়ে readable:

bash

# cURL
curl -X POST https://api.example.com/users \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer token123" \
  -d '{"name":"Ripon"}'

# HTTPie (same thing, simpler)
http POST https://api.example.com/users \
  name=Ripon \
  Authorization:"Bearer token123"

API Testing Workflow (Best Practice)

Development workflow:

1. API বানাও (backend)
2. Postman-এ Collection তৈরি করো
3. প্রতিটি endpoint test করো
4. Test scripts লেখো (automated)
5. Environment setup করো (dev/staging/prod)
6. Collection Runner দিয়ে full test
7. Newman দিয়ে CI/CD-তে integrate
8. Collection export করে team-এ share

Testing checklist per endpoint:
✅ Happy path (সব ঠিক থাকলে)
✅ Missing required fields
✅ Invalid data types
✅ Unauthorized access (no token)
✅ Forbidden access (wrong role)
✅ Not found (invalid ID)
✅ Duplicate data (conflict)
✅ Rate limiting
✅ Response time < threshold

সংক্ষেপে মনে রাখার সূত্র

Postman = Full-featured API platform (test, mock, docs, CI/CD)
Insomnia = Lightweight alternative (GraphQL, gRPC friendly)

Postman key features:
- Collections → organize requests
- Environments → dev/staging/prod switch
- Test Scripts → automated response check
- Collection Runner → bulk test
- Newman → CI/CD integration
- Mock Server → backend ছাড়াই frontend test

Workflow:
Build API → Postman test → Automate → CI/CD → Ship!

Interview Golden Lines

Postman is not just for sending requests — it's a complete API development platform with testing, mocking, and CI/CD.

Environment variables let you switch between dev, staging, and production with a single click.

Newman brings Postman tests into your CI/CD pipeline — if API tests fail, deployment stops.

Insomnia shines for GraphQL — its auto-complete and schema integration are better than Postman's.

The .http file approach (REST Client) is the most developer-friendly — it lives in your codebase and is version-controlled.

Postman ও Insomnia — API Testing Tools ​

API Testing Tool কেন দরকার? ​

Postman ​

Request পাঠানো (Basic) ​

Collections — Requests Organize করা ​

Environment Variables ​

Dynamic Variables ​

Pre-request Scripts ​

Test Scripts — Response Verify করা ​

Collection Runner — Bulk Test ​

Chain Requests — একটার output পরেরটার input ​

Mock Server ​

Newman — CLI Runner ​

Insomnia ​

Insomnia Features ​

Insomnia-র বিশেষত্ব — GraphQL ​

Template Tags ​

Postman vs Insomnia তুলনা ​

অন্যান্য API Testing Tools ​

Thunder Client (VS Code) ​

REST Client (VS Code) ​

HTTPie (CLI) ​

API Testing Workflow (Best Practice) ​

সংক্ষেপে মনে রাখার সূত্র ​

Interview Golden Lines ​

Postman ও Insomnia — API Testing Tools

API Testing Tool কেন দরকার?

Postman

Request পাঠানো (Basic)

Collections — Requests Organize করা

Environment Variables

Dynamic Variables

Pre-request Scripts

Test Scripts — Response Verify করা

Collection Runner — Bulk Test

Chain Requests — একটার output পরেরটার input

Mock Server

Newman — CLI Runner

Insomnia

Insomnia Features

Insomnia-র বিশেষত্ব — GraphQL

Template Tags

Postman vs Insomnia তুলনা

অন্যান্য API Testing Tools

Thunder Client (VS Code)

REST Client (VS Code)

HTTPie (CLI)

API Testing Workflow (Best Practice)

সংক্ষেপে মনে রাখার সূত্র

Interview Golden Lines