Postman Data Driven Testing

Introduction

In this article, we will look at how to perform Data Driven Testing using Postman Tool.

Pre-requisite

Postman collection with API request should be created.

Data driven Testing

Data Driven Testing is a Test design and execution strategy where the test scripts read test data from data sources (file or database) such as ADO objects, ODBC sources, CSV files, etc. rather than using hardcoded values

Advantages of Data-Driven Testing

It will provide the possibility to create Test Scripts at the early stage of development
Redundancy and duplication of Test Scripts are reduced
We can generate Test scripts with less amount of code.
All information like inputs, outputs, and the expected result is stored in the form of excel, CSV or JSON files
Provides flexibility in Test Scripts maintenance

Steps to perform Data Driven Testing in postman

Create a collection and create the API requests inside the collection.
Add your tests to the API request. I have covered this topic in a separate Article on how to write tests in Postman.
Create the data file in this example I am showing you with example of data driven from JSON file to the API request.
- I have shown example of the Post Request.
- JSON file looks like this. As you know the JSON file contains data in key value pair

[{
    "name": "hugo",
    "job": "leader"
},
{
    "name": "mike",
    "job": "developer"
},
{
    "name": "elis",
    "job": "designer"
}
]

Now we need to run the collection using collection runner option.
In the collection runner option click select file button.

Select the JSON test data file. (screenshot below),

Postman Data Driven Testing

Before running the collection you need to refer the testdata in your post body,

How to refer,

We need to refer the key of the testdata as a variable in your post body within braces as shown below.

Note
This step applies when you read data from CSV file or excel as well.

{
    "name": "{{name}}",
    "job": "{{job}}"
}

If your test data contains any numeric value then refer the key of the testdata as a variable without any quotes

Example

{
    "name": "{{name}}",
    "job": "{{job}}"
    "age":{{age}}
}

Screenshot on how to refer the test key variable

Postman Data Driven Testing

Now save your request
Once you provide the JSON Test Data File, you can Preview the data.
If any error is present in your JSON file, while uploading itself Postman will identify the errors present in your JSON data.
And you can notice that the iteration will also change as per the number of testdata that is present in your JSON data.

Screenshot of preview

Postman Data Driven Testing

Now click the run collection button. Your collection will run as per the test data present in your JSON data file.
Result window will be displayed(Screenshot)

Postman Data Driven Testing

Data Driven Tests Using CSV file

Create a collection and the API request you need to run.
Create a CSV file.
Add test data into the CSV file using commas.

Example of CSV file,

name,email
test,qaengineer
testertwo,developer

Click the three dot icon besides the collection and select the run collection option to open up collection runner
Collection Runner window will appear.
In the collection runner option click select file button.
Refer the CSV file(screenshot)

Postman Data Driven Testing

Add your tests to the API request.
Iterations are the no. of data rows in CSV file.
Preview button will display the preview of CSV file.

Screenshot of the CSV file preview,

Postman Data Driven Testing

Click on Run button in blue color.
Result window will be displayed.

Screenshot of run,

Postman Data Driven Testing

Summary

Hope this article will help you in performing Data Driven Testing using Postman Tool.

Thanks............