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The Complete Guide to Perform Manual REST API Testing Using Postman

by admin | Oct 27, 2021 | API Testing, Blog, Latest Post | 0 comments

Postman is one of the most popular software testing tools which is used for API testing. Postman is widely used by both software testers and developers for testing as it is easy to integrate with Continuous Integration (CI) & Continuous Development Pipelines. Postman sends an API request to the webserver and receives the response. As one of the leading QA companies, we have been doing our manual Rest API testing using Postman whenever it was deemed necessary. So if you are someone who is looking for a complete guide that explains everything from what is REST API to how it works to how it can be manually tested using Postman, you will definitely find this blog useful.

API (Application Programming Interface)

An API is a set of defined rules that enables computers or applications to communicate with one another. APIs sit between an application and the webserver and acts as an intermediary that processes data transfer between systems.

What is REST API?

• REST API (Representational State Transfer Application Program Interface) is an architectural style that allows the software to communicate with other software on the same device or over a network.
• REST APIs communicate via HTTP requests to perform standard database functions like creating, reading, updating, and even deleting records (also known as CRUD) within a resource.

Why REST API?

These are the major reasons as to why we choose REST API over the other options. REST API is

1. Easy to Learn & Implement

2. Easy to Build & Maintain

3. Scalable

4. Cacheable

5. Flexible and Portable

How does REST APIs work?

As stated earlier, REST APIs use HTTP requests for their communication. HTTP works as a request-response protocol between a client and server and enables client-to-server communication. For example, your web browser can be considered as the client, and the application on the computer that hosts the website can be termed as the server. So if your browser (client) submits an HTTP request to the server, the server will return a response that contains the status information of the request and the requested content if any were requested.

Common HTTP methods (CRUD commands) used in REST API:

Most of these commands have very straightforward names that make them self-explanatory. So once you have been introduced to them, it will be very easy for you to remember.

• GET – The GET method can be used to extract information from the given server using a given URI. It is worth noting that when you use the GET request, it should only extract the data and not have any other effect on the data. So no Payload/Body is required.
• POST – As the name suggests, a POST request is used to send data to the server. Data like customer information, files, and so on can be sent using HTML forms.

• PUT – Using PUT, you will be able to replace all the current representations of the target resource with the uploaded content.
• DELETE – It can be used to remove all the current representations of the target resource given by a URI.

There are other CRUD commands like patch, copy, and so on as well. So once you are thorough with these basics, you can explore them.

API Contract

We have seen the basics of REST API that you will need to know. There are also a few basics of Postman that you should be familiar with. But before we can move forward, we have to explore a few aspects of the API contract as you’d have to know the following information to perform manual REST API testing using Postman.

Endpoint:

It is the address where the API is hosted on the Server. An End Point Request URL can be constructed as below
Base URL/resource/(Query/Path)Parameters

Resources:

They represent the API/Collection that can be accessed from the Server. We have listed a few common examples below to help you understand better.

• Google.com/maps
• google.com/search
• google.com/images

Here maps, search and images are the resources of Google.com which is the Base URL.

Path Parameters:

Path parameters are the variable parts of a URL path. They are generally used to point to a specific resource within a collection in the same way how a user is identified by ID.

Example for Path Parameters:

• https://www.google.com/Images/1123343
• https://www.google.com/docs/1123343
• https://amazon.com/orders/112

Here 1123343, and 112 are the parameters

Query Parameters:

Query Parameters are primarily used to sort or filter the resources. They can be identified with ”?” (A Question Mark). You’ll be able to identify them once you see a few examples.

• https://amazon.com/orders?sort_by=07/09/2021
• https://www.google.com/search?q=newyork&oq=newyork&aqs=chrome..69i57j0l7.2501j0j7&sourceid=chrome&ie=UTF-8

Here orders and search are your resources and they are sorted and filtered by the query parameter that is followed by the “?”.

Headers/Cookies:

Headers represent the meta-data associated with the API request and its response. In layman’s terms, it will be used to send additional details to the API for processing our request. An example of it would be the authorization details.

Sample API Contract for Basic CRUD commands:

Apart from these values, we would also have to know about the HTTP method in use, the body, content types of the parameter and response (either Application or JSON), and also the response value. You will get a clear idea of these aspects when we see a few examples.

1. Request to Log in – Successful

Parameters

Base URL: https://reqres.in

Request : /api/login

Request Type: POST

Body :

{
    "email": "[email protected]",
    "password": "cityslicka"
}

Parameter Content Type: application/json

Responses:

Response Content Type: application/json

Response Code : 200

Description : OK

Response Value :

{
    "token": "QpwL5tke4Pnpja7X4"
}

2. Request to Get a List of Users

Parameters

Base URL: https://reqres.in

Request: /api/users

Request Type: GET

Responses:

Response Content Type: application/json

Response Code : 200

Description : OK

Response Value :

{
    "page": 1,
    "per_page": 6,
    "total": 12,
    "total_pages": 2,
    "data": [
        {
            "id": 1,
            "email": "[email protected]",
            "first_name": "George",
            "last_name": "Bluth",
            "avatar": "https://reqres.in/img/faces/1-image.jpg"
        },
        {
            "id": 2,
            "email": "[email protected]",
            "first_name": "Janet",
            "last_name": "Weaver",
            "avatar": "https://reqres.in/img/faces/2-image.jpg"
        },
        {
            "id": 3,
            "email": "[email protected]",
            "first_name": "Emma",
            "last_name": "Wong",
            "avatar": "https://reqres.in/img/faces/3-image.jpg"
        },
        {
            "id": 4,
            "email": "[email protected]",
            "first_name": "Eve",
            "last_name": "Holt",
            "avatar": "https://reqres.in/img/faces/4-image.jpg"
        },
        {
            "id": 5,
            "email": "[email protected]",
            "first_name": "Charles",
            "last_name": "Morris",
            "avatar": "https://reqres.in/img/faces/5-image.jpg"
        },
        {
            "id": 6,
            "email": "[email protected]",
            "first_name": "Tracey",
            "last_name": "Ramos",
            "avatar": "https://reqres.in/img/faces/6-image.jpg"
        }
    ],
    "support": {
        "url": "https://reqres.in/#support-heading",
        "text": "To keep ReqRes free, contributions towards server costs are appreciated!"
    }
}

3. Request to update user Information

Parameters

Base URL: https://reqres.in

Request : /api/users/{{User_ID}}

User_ID=2

Request Type: PUT

Body :

{
    "name": "morpheus",
    "job": "zion resident"
}

Parameter Content Type: application/json

Responses:

Response Content Type: application/json

Response Code : 200

Description : OK

Response Value :

{
    "name": "morpheus",
    "job": "zion resident",
    "updatedAt": "2021-10-05T19:20:33.979Z"
}

4. Request to Get a List of Users

Parameters

Base URL: https://reqres.in

Request : /api/users/{{User_ID}}

User_ID=2

Request Type: DELETE

Responses:

Response Content Type: application/json

Response Code : 204

Description : OK

Response Value :[]

Now that we have fully covered all the prerequisites when it comes to REST API, let’s see why we use test REST APIs and explore a few other prerequisites that will be required to perform Rest API testing using Postman.

Why Postman tool?

Postman is a simple GUI for sending HTTP requests and viewing its responses. It is built upon an extensive set of power tools, which are incredibly easy to use. Postman helps you perform a variety of functions and has a lot of useful functionalities as well.

• Since Postman is accessible from anywhere, you have to just install it into the device and access it by logging into the account.
• Your test suites will be more organized as Postman allows users to build collections for their API calls. Every set can create multiple requests and subfolders.
• Using Postman, you’ll be able to test checkpoints with the verification of the successful HTTP response status that will be added to every API call.
• Automation Testing becomes easier as several iterations of the tests can be performed by using the Collection Runner or Newman. So you can save a lot of time when performing repetitive tests.
• As Postman makes it easy to create environments, you can design multiple environments and reduce the replication of tests as you’ll be able to use the same collection for a different setting.
• The postman console helps to track what data is being retrieved makes it possible to effectively debug the tests.
• The scope for collaboration is also high as you can import or export your collections & environments and share those files. You can also use a direct connection to share the collections.
• Postman supports continuous integration as well.
• You can use Postman by either downloading & installing their application or use their web version. It is a good option to have as both offer great performance.

How to create API requests in Postman

Learning how to create API requests is an integral part of learning how to perform manual REST API Testing using Postman. You will need to know more about the following 2 features to create an API request.

• Workspace
• Collections

Workspace in Postman:

Postman Workspaces acts as a common working area where you can group your API projects together and use API builder to define APIs or generate API elements. So they are helpful in organizing your API work better and collaborating with your teammates as well. Now let’s see how to create one.

Creating a Workspace in Postman:

Click on the Workspace dropdown in the header -> New Workspace -> WorkSpaceName (Type any workspace name you wish) -> Create Workspace.

Collections in Postman:

• Postman Collections are Executable API Descriptions Postman’s collection folders make it easy to keep your API requests and elements organized.
• Generate Collections from API schemas Generate a collection from an API schema to view and edit each request.
  Creating Collections in Postman:

Click on File -> New -> Collection -> CollectionName (Assign a Collection Name as you wish)

OR

Click Collection -> Create Collection Icon (+) -> CollectionName (Enter a Collection Name of your wish)

For testing the CRUD commands, we are going to use the information which is present in the above mention API contract.

Testing POST Request to Log in – Successful:

To make a POST request, click on the More option icon (…) -> Add Request -> Login User

1. From the Dropdown select POST

2. In the “Enter request URL” text box, type the following (URL): https://reqres.in/api/login

3. Click on Body Tab, select the ‘Raw’ radio button, and then the JSON format from the dropdown list.

4. In the text box, paste the Login Credentials:

{
 "email": "[email protected]",
 "password": "cityslicka
}

5. Click on the Send button

6. You should be able to see the below response:

7. Also, make sure to check for the correct status code here. In this case, you should get: ‘Status: 200’ as shown in the image below.

Testing GET Request to Get the List of Users:

To make a GET request, you have to click on the More options icon (…) -> Add Request -> Request to Get List of Users (Assign any requested name you wish)

1. From the Dropdown list, select GET

2. Type the mentioned URL (https://reqres.in/api/users) in the “Enter request URL” text box.

3. Click on the Send button.

4. You’ll be able to see the below response:

5. Once again, check for the status code and see if it is ‘Status: 200’.

Testing PUT Request to update user Information:

Same as above, you have to click on the More option Icon(…) ->Add Request -> Request to Update user Information (Enter any request name of your choice)

1. Click on ‘PUT’ from the dropdown list.

2. In the “Enter request URL” text box that appears, type this URL: https://reqres.in/api/users/2

3. Click on the ‘Body’ Tab, select the ‘Raw’ radio button, and then choose the JSON format from the dropdown.

4. Paste the Login Credentials in the text box:

{
    "name": "morpheus",
    "job": "zion resident"
}

5. Click on the ‘Send’ button

6. You will see the below response:

7. Check if the status is shown as ‘200 OK’.

Testing DELETE Request to Remove Users from Database

Click on the More option Icon (…) -> Add Request -> Request to Get the list of Users (Enter any request name you wish)

1. From the Dropdown list of options, select ‘DELETE’.

2. Type this URL https://reqres.in/api/users in the “Enter request URL” text box.

3. Click on the ‘Send’ button

4. Check is you see the below response:

5. Check if ‘Status: 200 OK’ is visible as shown in the image below.

Conclusion:

It is evident that the steps we saw for each request were almost identical to each other. So by now, you should have no trouble in performing Rest API testing using Postman in an effective way to ensure high quality. As a leading manual testing services provider, we have often used Postman for our manual testing projects. But Postman can also be used for automation testing with the help of Test scripts.

A Wall-to-Wall Postman Guide for API Testing

by admin | Jul 13, 2021 | API Testing, Blog, Latest Post | 0 comments

Postman is an API (Application Programming Interface) development tool that allows users to perform GET, POST, PUT, DELETE, and many other requests to the web service API. Postman allows you to manually test your APIs in both its desktop and web-based applications. However, it also has the ability to automate these tests by writing JavaScript assertions on your API endpoints. As one of the best QA companies, we always thrive on using the best tools for our projects, and Postman has become one of our go-to tools when it comes to API testing. So in this Postman Guide, we will be exploring how to perform the above said requests like Post, Request, and so on. But before we proceed further, let’s have a brief introduction to API testing.

What is API Testing?

API testing is a type of software testing where application programming interfaces (APIs) are tested to determine if they meet the expected functionality, reliability, performance, and security levels. It only concentrates on the business logic layer of the software architecture.

Some of the important components in Postman

• Pre-Request Script:

Users will be able to write a script to manipulate the data being sent with the request. The pre-request script will run before the request is sent.

• Tests:

This is the test editor where the users can configure the test cases that are being validated once the request has been fulfilled.

• Environment:

The environment in postman is a set of key-value pairs which is used to set dynamic values.

• Collections:

A group of requests will be displayed under collections, and it can be used to organize and keep track of related requests.

Postman Guide to create & run the First API Request:

First and foremost, we have to create a new workspace and click on the New option under ‘File’, and then select ‘Request’.

Enter the name as ‘GET Request’ and then click on + NEW COLLECTION. Following which we will be able to assign a suitable name for the collection.

Once we click on Save, the collection name will be displayed with your API in it. Now that we have prepped everything, let’s make the first API call by following the below steps,

We have to enter the URL in the address bar and click on the ‘Send’ button to see the response.

The response will include details such as the status code, time, size, headers, and cookies alongside the Body.

Status Code

So if you take a look at the above image, the HTTP status code is shown to be “200 OK”, which means that everything has worked as expected and that our request is successful.

Time

Right beside the status code, we can see that the time taken to complete the request is 509 ms.

Size

The other available parameter is the size of the requested data, we can see that size is mentioned to be 1.92 KB in the above image.

Note:If we hover the mouse over the time and response values, we will be able to view more details

To save this response, we can simply click on the ‘Save Response’ option.

As stated above, we can also see the body, which is an HTML file in the image. Clicking on the ‘Preview’ option under the body will enable us to view the body in HTML format.

We can click on ‘Cookies’ to view the session-related information and on ‘Headers’ to view other details such as date, content type details, etc.

So by following the above instructions, we have successfully made our first request! Now let’s find out how to send a post request in Postman.

Postman Guide to send a Post Request:

Post is one of the HTTP methods that can be used to add new resources like a webpage and so on. So if we want to create and add a new user to the database, we can utilize the Post request. Likewise, we can also use Post requests for form submissions, authentication requests, and so on.

Let’s see how Post request works:

In Postman, we have an endpoint that responds back whenever we send a request. So, now we are going to send a particular key-value pair in the JSON format to a server.

First, we have to set the HTTP Method to POST.

Next, we have to mention the URL in the address bar.

In the Body tab of the request editor, we should select the ‘Raw’ option and then select JSON from the dropdown list.

We have chosen Raw with JSON as it is one of the most commonly used Post Requests.

So enter the REQUEST in the Body and click on ‘Send’.

We can see that the user has been created in the above image. In addition to that, we also have the same type of information that we saw earlier that includes status code, time, and so on.

But this time around, we have the status code displayed as 201, which implies that the request has been created.
Click on ‘Save’ to save this request.

‘POST REQUEST’ can be used to add a set of data into the server database. But it is crucial to make sure that the fields are filled with the correct data type, as any incorrect data will result in a 400 Bad Request.

Postman Guide to send a DELETE Request:

Previously, we saw how to send a post request in which we created a user and sent a body. Now let’s see how we can delete a request in Postman. We can use the DELETE HTTP Method to delete an existing record of a user in a database. The expected response in the Status for this is 204.

So primarily, we would have to set the HTTP Method to DELETE, then mention the URL in the address bar, and also mention the final endpoint.

Once the above actions have been completed, we can go ahead and click on ‘Send’.

So as expected, we have the Status Code shown as 204, which denotes that the particular resource has been deleted.

But what if the user has some additional parameters? We can pass query parameters and add them to the body section for deleting those resources as well.

Collections

Collections are nothing but a group of requests grouped into a folder. The simplest example of this would be the way we organize the files on our computers or mobile phones. Let’s say we have multiple files of different formats like text files, audio files, video files, etc. We most probably would create new folders and segregate all the files based on their format.

In the same way, we can create different groups using POSTMAN, and each group can have its own type of request. In addition to having the option to create a collection, we will also be able to share this collection with the team members and encourage healthy collaboration. The other advantage is that since we can share the collection, we will also be able to perform various actions like assigning roles, documentation, mock servers, monitors, etc.

Postman Guide to create a collection:

Now that we have seen the purpose of collection, let’s find out how to create one by making use of the following steps.

Click on the ‘New‘ option, then click on ‘Collection’, and enter the Collection Name. We will be able to click on ‘Create’ once we have also added the description of the collection.

Now we can see that we have several options like Run, Share, and so on displayed.

Here we can click on ‘Add Requests’, or replace any existing requests.

Once we click on ‘Run’, a new window will be opened, enabling us to run the collection by clicking on ‘Run My Collection’.

So now we are able to see results for all the requests under the collection, making it evident that we can save an ample amount of time by running multiple requests at a time.

We can click on the ‘Run Again’ option to rerun the collection. Following this, we can click on ‘Export Results’ to export the results as a JSON file. If you take a look at the below image, we can understand that it can be downloaded as well.

Different features of collections

• We can add the collections to favorites.

• It helps users share & assign the roles, create fork & pull requests, and also merge changes.

• We can create a duplicate of collections and export them.

Environment in Postman

It is very important to create distinct environments where one is dedicated for testing, one for development, and another for production. An environment is nothing but a set of variables or key-value pairs which we can be used in our requests. We can also change the value of the variables to pass the data between requests and tests. But how we do create an Environment? Let’s find out.

Postman Guide to create an Environment:

1. First, we have to click on the ‘Environments’ option.

2. Then we have to click on the ‘Add’ icon.

3. We can now enter the Environment name.

4. Followed by which we can enter the variable name to use it with the request.

The initial value is shared with your team when you share the variable in a collection as it will be shared with the collaborators who have access to the environment.

The current value is always used when a request is sent as they are never synced to Postman’s servers. If left untouched, the current value will automatically be assumed as the initial value.

Click on ‘Add’ to create the environment. Once the environment has been created, users can share, copy or even download them if needed.

Global variables in Postman

Global variables allow users to access data between collections, requests, test scripts, and environments. Global variables are not dependent on any environment, making them available for all the requests. They are available throughout the workspace. But on contrary, local variables are available only in particular environments.

When to use Global and Local Variables

When we have multiple key-value pairs which do not depend on any environment, we can make them a Global variable.

Local variables can be used when we have key-value pairs which will change or differ between the environments.

Conclusion:

We hope you have enjoyed reading our Postman Guide for API Testing, as Postman is an effective tool when it comes to API testing. We have just seen the tip of the iceberg here, as these are the most important and basic functionalities every tester must know. As a leading test automation company, we have used Postman in various projects and have always been pleased with its performance. So one can always explore the many more useful functionalities that Postman has to enhance their API testing skills.