How To Install Postman In Ubuntu 16.04 Using Terminal

How to Install Postman in Ubuntu 16.04 Using Terminal

Postman is a powerful tool for API testing and development. It allows you to send requests, inspect responses, and organize your API workflows. While Postman offers a desktop application, you can also install and use it from the command line, which can be useful for automated testing and scripting. This guide will walk you through installing Postman and setting it up on your Ubuntu 16.04 system using the terminal.

Prerequisites

Ubuntu 16.04 LTS (Xenial Xerus): Ensure you have Ubuntu 16.04 installed on your system.
Node.js and npm: You need Node.js and npm (Node Package Manager) installed. These are essential for using the Postman CLI. You can install them using the following command:
Terminal window
```
sudo apt-get update
sudo apt-get install nodejs npm
```

Installing Postman CLI

Open Terminal: Open a terminal window by pressing Ctrl+Alt+T.
Download the Postman CLI: Use the following command to download and install the Postman CLI package globally:
Terminal window
```
sudo npm install -g newman
```
- npm: Node Package Manager
- -g: Global installation. This allows you to use the Postman CLI from any directory.
- newman: The name of the Postman CLI package.
Verify Installation: Check if the installation was successful by running the following command:
Terminal window
```
newman -v
```
You should see the installed version of Newman printed in the terminal.

Using the Postman CLI

1. Create a Collection:

Collections in Postman organize a group of API requests. A collection can represent an entire API or a specific feature set. You can create a collection using the Postman desktop application or directly using the Postman CLI.
The Postman CLI expects a collection in JSON format. A sample collection can look like this:

   {
     "info": {
       "_postman_id": "b0989f19-2c04-400a-b881-e20f41d7b0f6",
       "name": "My First Collection",
       "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
     },
     "item": [
       {
         "name": "Get User",
         "request": {
           "method": "GET",
           "header": [],
           "url": {
             "raw": "http://example.com/users",
             "protocol": "http",
             "host": [
               "example",
               "com"
             ],
             "path": [
               "users"
             ]
           },
           "body": {}
         },
         "response": []
       }
     ]
   }

Save this collection: Create a file named my-collection.json and paste the code above.

2. Sending Requests with Newman:

Run a request from a collection: The newman command is used to send requests and get results from your Postman Collections. To execute the collection you just created, run the following command:

newman run my-collection.json

Running a single request: You can also run single requests from a collection directly without needing the entire collection file:

newman run my-collection.json -e get-user.json

The -e option specifies an environment file that contains variables that you can use in your tests. The get-user.json file would typically contain variables for endpoint URLs.

3. Environment Variables:

Environments allow you to manage configuration settings like API keys, base URLs, and other variables, ensuring you can seamlessly test across various environments (development, staging, production).
Create an Environment File: To create an environment variable file, you need to save a .json file with the following structure (example below):

{
  "id": "630e4624-f71f-43b3-8e66-2535c4004507",
  "name": "My Dev Environment",
  "values": [
    {
      "key": "baseUrl",
      "value": "http://example.com"
    }
  ]
}

Use Environments: You can use environment variables in your collection. For example:

   {
     "info": {
       "_postman_id": "b0989f19-2c04-400a-b881-e20f41d7b0f6",
       "name": "My First Collection",
       "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
     },
     "item": [
       {
         "name": "Get User",
         "request": {
           "method": "GET",
           "header": [],
           "url": {
             "raw": "{{baseUrl}}/users",
             "protocol": "http",
             "host": [
               "{{baseUrl}}",
               "com"
             ],
             "path": [
               "users"
             ]
           },
           "body": {}
         },
         "response": []
       }
     ]
   }

Run with specific environment: You can now run your collection using an environment file to make it more flexible:

newman run my-collection.json -e my-dev-environment.json

4. Assertions:

Assertions are used to validate different aspects of the response, ensuring that your API functions correctly. Newman supports several ways to write assertions using Javascript.
Create Assertions: You can add assertions to your collection using the test keyword within your JSON:

   {
     "info": {
       "_postman_id": "b0989f19-2c04-400a-b881-e20f41d7b0f6",
       "name": "My First Collection",
       "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
     },
     "item": [
       {
         "name": "Get User",
         "request": {
           "method": "GET",
           "header": [],
           "url": {
             "raw": "http://example.com/users",
             "protocol": "http",
             "host": [
               "example",
               "com"
             ],
             "path": [
               "users"
             ]
           },
           "body": {}
         },
         "response": [],
         "test": [
           "pm.test('Status code is 200', function () {",
           "    pm.response.to.have.status(200);",
           "});"
         ]
       }
     ]
   }

Run with Assertions: When the newman command runs, it will execute all tests within your collection:

newman run my-collection.json

pm.response.to.have.status(200); checks that the response status code is 200 (OK).

Generating Reports

Generate HTML reports:* You can create detailed HTML reports to visualize the results of your API testing. For this, you need the newman-reporter-html package:
Terminal window
```
sudo npm install -g newman-reporter-html
```
Run tests and create HTML report: This command will generate an output.html file in the same location as your collection:
Terminal window
```
newman run my-collection.json -r html -o output.html
```

Note: The Postman CLI (Newman) is a powerful tool for testing APIs and integrating with your testing workflows.