What is API

What is API

Application Programming Interface: allows two applications to talk to each other

What is REST API

REST (Representational State Transfer): A set of functions for developers to perform requests and receive responses using HTTP protocol

Challenges under API testing

1. API Documentation (need endpoint, parameters, resources, data)
2. Access to DB (Validate response by comparing response to DB)
3. Authorization overhead (Handle tokens)

Core components of HTTP request

1. HTTP request methods
2. URI
3. Resources and parameters
4. Request header (JSON, XML)
5. Request body (message content)

What is Payload

• Payload/body is secured input data sent to API
• In JSON

What is JSON

• JavaScript Object Notation
• Data format represented as String-text

Authentication Techniques used in API’s

1. Session/Cookie based Authentication
2. Basic Authentication
3. Digest Authentication
4. OAuth

Why API testing is suitable for automation testing

API testing is:

1. Light-weight
2. More stable than UI testing

What to verify in API testing

1. Verify the accuracy of data (if is as expected)
2. Check HTTP status code
3. Response time
4. Error codes if API return errors
5. Check Authorization
6. Non-functional testing

Path parameter and Query parameter

// below is an API request URL
http:/abcd.com/orders/11234?location=IND

// End point: http:/abcd.com
// Resource: orders

After / : path parameter

After ? : query parameter

API testing vs UI testing

API: back-end

UI: front-end

Soap WebServices

Simple Object Access Protocol: it is a XML based message protocol

Serialization && Deserialization

Serialization: Convert Java obj –> JSON (Request body/payload)

Deserialization: Convert JSON –> Java obj

JSON path example

courses[0].details.site

API calling examples

Python:

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import requests
r = requests.get("https://www.pythonhow.com/real-estate/rock-springs-wy/LCWYROCKSPRINGS", headers={'User-agent': 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:61.0) Gecko/20100101 Firefox/61.0'})
c=r.content

Dart:

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final response = await http.post(url, body: json.encode(requestModel.toJson())); 
print(response.headers['set-cookie']);
print(response.statusCode);

final response = await http.post(url, headers: {'Authorization': token}, body: json.encode(requestModel.toJson()));