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Install Postman, GET, POST, Call API's, Parameterize Requests, Tests, Collections Runner using Newman #339

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Install Postman, GET, POST, Call API's, Parameterize Requests, Tests, Collections Runner using Newman

Postman Tutorial: How to Install and use Postman for API Testing Thomas Hamilton
By Thomas Hamilton
Updated November 29, 2021

https://www.guru99.com/postman-tutorial.html

https://learning.postman.com/docs/getting-started/installation-and-updates/#installing-postman-on-linux

https://github.com/coding-to-music/postman-testing

You can install Postman on Linux by manually downloading it, using the Snap store link, or with the command snap install postman.

sudo snap install postman

To install manually, download and unzip the app, for example into the opt directory. You will need sudo privileges.

To start the app from a launcher icon, create a desktop file, naming it Postman.desktop and saving it in the following location:

~/.local/share/applications/Postman.desktop

Enter the following content in the file, replacing opt if you extracted the file somewhere else, and save it:

[Desktop Entry]
Encoding=UTF-8
Name=Postman
Exec=/opt/Postman/app/Postman %U
Icon=/opt/Postman/app/resources/app/assets/icon.png
Terminal=false
Type=Application
Categories=Development;
mkdir -p ~/.local/share/applications/

touch ~/.local/share/applications/Postman.desktop

From StackOverflow https://stackoverflow.com/questions/42996358/how-to-install-start-postman-native-v4-10-3-on-ubuntu-16-04-lts-64-bit/43723749#43723749

sudo wget https://dl.pstmn.io/download/latest/linux64 -O postman.tar.gz
sudo tar -xzf postman.tar.gz -C /opt
sudo rm postman.tar.gz
sudo ln -s /opt/Postman/Postman /usr/bin/postman

https://www.postman.com/downloads/


wget -o Postman-linux-x86_64-9.3.1.tar.gz https://dl.pstmn.io/download/latest/linux64/Postman-linux-x86_64-9.3.1.tar.gz

wget  https://dl.pstmn.io/download/latest/linux64/Postman-linux-x86_64-9.3.1.tar.gz

Validate JSON

https://jsonformatter.curiousconcept.com/#

Postman Tutorial

https://www.guru99.com/postman-tutorial.html

We will use the following URL for all examples in this Postman tutorial

Postman Workspace

https://web.postman.co/workspace/My-Workspace

How to use Postman to execute APIs

Below is the Postman Workspace. Let’s explore the step by step process on How to use Postman and different features of the Postman tool!

How to use Postman to execute APIs

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  1. New – This is where you will create a new request, collection or environment.
  2. Import – This is used to import a collection or environment. There are options such as import from file, folder, link or paste raw text.
  3. Runner – Automation tests can be executed through the Collection Runner. This will be discussed further in the next lesson.
  4. Open New – Open a new tab, Postman Window or Runner Window by clicking this button.
  5. My Workspace – You can create a new workspace individually or as a team.
  6. Invite – Collaborate on a workspace by inviting team members.
  7. History – Past requests that you have sent will be displayed in History. This makes it easy to track actions that you have done.
  8. Collections – Organize your test suite by creating collections. Each collection may have subfolders and multiple requests. A request or folder can also be duplicated as well.
  9. Request tab – This displays the title of the request you are working on. By default, “Untitled Request” would be displayed for requests without titles.
  10. HTTP Request – Clicking this would display a dropdown list of different requests such as GET, POST, COPY, DELETE, etc. In Postman API testing, the most commonly used requests are GET and POST.
  11. Request URL – Also known as an endpoint, this is where you will identify the link to where the API will communicate with.
  12. Save – If there are changes to a request, clicking save is a must so that new changes will not be lost or overwritten.
  13. Params – This is where you will write parameters needed for a request such as key values.
  14. Authorization – In order to access APIs, proper authorization is needed. It may be in the form of a username and password, bearer token, etc.
  15. Headers – You can set headers such as content type JSON depending on the needs of the organization.
  16. Body – This is where one can customize details in a request commonly used in POST request.
  17. Pre-request Script – These are scripts that will be executed before the request. Usually, pre-request scripts for the setting environment are used to ensure that tests will be run in the correct environment.
  18. Tests – These are scripts executed during the request. It is important to have tests as it sets up checkpoints to verify if response status is ok, retrieved data is as expected and other tests.

Working with GET Requests

https://jsonplaceholder.typicode.com/users
In the workspace

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Working with POST Requests

Post requests are different from Get request as there is data manipulation with the user adding data to the endpoint. Using the same data from the previous tutorial in Get request, let’s now add our own user.

Step 1)

Click a new tab to create a new request.

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Working with POST Requests

Step 2)

In the new tab

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Set your HTTP request to POST. Input the same link in request url: https://jsonplaceholder.typicode.com/users switch to the Body tab Working with POST Requests

Step 3)

In Body,

Click raw Select JSON

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Working with POST Requests

Step 4)

Copy and paste just one user result from the previous get request like below. Ensure that the code has been copied correctly with paired curly braces and brackets. Change id to 11 and name to any desired name. You can also change other details like the address.

[
    {
        "id": 11,
        "name": "Krishna Rungta",
        "username": "Bret",
        "email": "Sincere@april.biz",
        "address": {
            "street": "Kulas Light",
            "suite": "Apt. 556",
            "city": "Gwenborough",
            "zipcode": "92998-3874",
            "geo": {
                "lat": "-37.3159",
                "lng": "81.1496"
            }
        },
        "phone": "1-770-736-8031 x56442",
        "website": "hildegard.org",
        "company": {
            "name": "Romaguera-Crona",
            "catchPhrase": "Multi-layered client-server neural-net",
            "bs": "harness real-time e-markets"
        }
    }
]

Working with POST Requests

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Note: Online Post request should have the correct format to ensure that requested data will be created. It is a good practice to use Get first to check the JSON format of the request. You can use tools like https://jsonformatter.curiousconcept.com/

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Working with POST Requests

Step 5)

Next,

Click Send. Status: 201 Created should be displayed Posted data are showing up in the body.

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How to Parameterize Requests

Data Parameterization is one of the most useful features of Postman. Instead of creating the same requests with different data, you can use variables with parameters. These data can be from a data file or an environment variable. Parameterization helps to avoid repetition of the same tests and iterations can be used for automation testing.

Parameters are created through the use of double curly brackets: {{sample}}. Let’s take a look at an example of using parameters in our previous request:

How to Parameterize Requests

Now let’s create a parameterize get request.

Step 1)

Set your HTTP request to GET Input this link: https://jsonplaceholder.typicode.com/users. Replace the first part of the link with a parameter such as {{url}}. Request url should now be {{url}}/users. Click send. There should be no response since we have not set the source of our parameter.

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How to Parameterize Requests

Step 2)

To use the parameter you need to set the environment

Click the eye icon Click edit to set the variable to a global environment which can be used in all collections.

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How to Parameterize Requests

Step 3)

In variable,

set the name to the url which is https://jsonplaceholder.typicode.com click Save.

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How to Parameterize Requests

Step 4)

Click close if you see the next screen

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How to Parameterize Requests

Step 5)

Go back to your Get request then click send. There should now be results for your request.

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How to Parameterize Requests *Note: Always ensure that your parameters have a source such as an environment variable or data file to avoid errors.

How to Create Postman Tests

Postman Tests are JavaScript codes added to requests that help you verify results such as successful or failed status, comparison of expected results, etc. It usually starts with pm.test. It can be compared to asserts, verify commands available in other tools.

Let’s do some basic API testing using Postman for our parameterize requests from the previous lesson.

Step 1)

Go to your GET user request from the previous tutorial.

Switch to the tests tab. On the right side are snippet codes. From the snippets section, click on “Status code: Code is 200”. The pane is auto-populated

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API testing

Step 2)

Now click Send. The test result should now be displayed.

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API testing

Step 3)

Go back to the test tab and let’s add another test. This time we will compare the expected result to the actual result.

From the snippets section, click on “Response body:JSON value check”. We will be checking if Leanne Graham has the userid 1.

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API testing

Step 4)

  1. Replace “Your Test Name” from the code with “Check if user with id1 is Leanne Graham” so that the test name specifies exactly what we want to test.
  2. Replace jsonData.value with jsonData[0].name. To get the path, check the body in Get result earlier. Since Leanne Graham is userid 1, jsonData is in the first result which should start with 0. If you want to get the second result, use jsonData[1] and so on for succeeding results.
  3. In to eql, input “Leanne Graham”
pm.test("Check if user with id1 is Leanne Graham", function () {
    var jsonData = pm.response.json();
    pm.expect(jsonData[0].name).to.eql("Leanne Graham");
});

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API testing

Step 5)

Click send. There should now be two passed test results for your request.

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API testing *Note: There are different kind of tests that can be created in Postman. Try to explore the tool and see what tests will fit your needs.

How to Create Collections

Collections play an important role in organizing test suites. It can be imported and exported making it easy to share collections amongst the team. In this tutorial, we will learn how to create and execute a collection.

Let’s start in creating a collection:

Step 1)

Click on the New button at the top left corner of the page.

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How to Create Collections

Step 2)

Select Collection. Create collection window should pop up.

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How to Create Collections

Step 3)

Input the desired collection name and description then click create. A collection should now be created.

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How to Create Collections

Step 4)

Go back to the previous Get request. Click Save

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How to Create Collections

Step 5)

Select Postman Test Collection. Click Save to Postman Test Collection

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How to Create Collections

Step 6)

Postman test collection should now contain one request.

alt text How to Create Collections

Step 7)

Repeat steps 4-5 for the previous Post request so that collection will now have two requests.

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How to Create Collections

How to Run Collections using Collection Runner

There are two ways to run a collection which is the Collection Runner and Newman. Let’s begin by executing the collection in Collection Runner.

Step 1)

Click on the Runner button found at the top of the page next to the Import button.

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How to Run Collections using Collection Runner

Step 2)

Collection Runner page should appear such as below. Following is the description of various fields

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How to Run Collections using Collection Runner

Step 3)

Run your Postman Test Collection by setting up the following:

Choose Postman test collection- Set iterations as 3 Set delay as 2500 ms Click on Run Postman Test… button

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How to Run Collections using Collection Runner

Step 4)

Run Results page should be displayed after clicking the Run button. Depending on the delay, you should see the tests as they execute.

Once tests have finished, you can see the test status if it is Passed or Failed and the results per iteration. You see Pass status for the Get Requests Since we did not have any tests for Post, there should be a message that the request did not have any tests.

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How to Run Collections using Collection Runner

You can see how important it is that there are tests in your requests so that you can verify HTTP request status if successful and the data is created or retrieved.

How to Run Collections using Newman

Another way to run a collection is via Newman. The main differences between Newman and Collection Runner are the following:

  1. Newman is an add-on for Postman. You will need to install it separately from the Native App.
  2. Newman uses the command line while Collection Runner has a GUI.
  3. Newman can be used for continuous integration.

To install Newman and run our collection from it, do the following:

Step 1)

Install nodejs using this link: http://nodejs.org/download/

Step 2)

Open the command line and enter

 npm install -g newman

Newman should now be installed on your computer.

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How to Run Collections using Newman

Step 3)

Once Newman has been installed, let’s go back to our Postman workspace.In the Collections box, click on the three dots. Options should now appear. Select Export.

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How to Run Collections using Newman

Step 4)

Choose Export Collection as Collection v2.1 (Recommended) then click Export.

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How to Run Collections using Newman

Step 5)

Select your desired location then click Save. It is advisable to create a specific folder for your Postman tests. A collection should now be exported to your chosen local directory.

Step 6)

We will also need to export our environment. Click on the eye icon beside the environment dropdown in Global, select Download as JSON. Select your desired location then click Save. It is advisable that the environment should be in the same folder as your collection.

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How to Run Collections using Newman

Step 7)

Environment should now be exported to the same local directory as Collection.

Step 8)

Now go back to command line and change the directory to where you have saved the collection and environment.

 cd C:\Users\Asus\Desktop\Postman Tutorial

Step 9)

Run your collection using this command:

cd postman-tests

ls -l 
-rw-rw-r-- 1 tmc tmc  438 Dec  9 00:58 Test-Environment.postman_environment.json
-rw-rw-r-- 1 tmc tmc 5370 Dec  9 00:57 Postman-Test-Collection.postman_collection.json

# original request:
# newman run PostmanTestCollection.postman_collection.json -e Testing.postman_globals.json

newman run Postman-Test-Collection.postman_collection.json -e Test-Environment.postman_environment.json

Output

newman

Postman Test Collection

→ Users List
  GET https://jsonplaceholder.typicode.com/users [200 OK, 6.78kB, 141ms]
  ✓  Status code is 200

→ https://jsonplaceholder.typicode.com/users
  GET https://jsonplaceholder.typicode.com/users [200 OK, 6.79kB, 24ms]
  ✓  Status code is 200
  ✓  Check if user with id1 is Leanne Graham

→ {{url}}/users
  GET https://jsonplaceholder.typicode.com/users [200 OK, 6.78kB, 22ms]
  ✓  Status code is 200
  ✓  Response time is less than 200ms

┌─────────────────────────┬───────────────────┬───────────────────┐
│                         │          executed │            failed │
├─────────────────────────┼───────────────────┼───────────────────┤
│              iterations │                 1 │                 0 │
├─────────────────────────┼───────────────────┼───────────────────┤
│                requests │                 3 │                 0 │
├─────────────────────────┼───────────────────┼───────────────────┤
│            test-scripts │                 3 │                 0 │
├─────────────────────────┼───────────────────┼───────────────────┤
│      prerequest-scripts │                 0 │                 0 │
├─────────────────────────┼───────────────────┼───────────────────┤
│              assertions │                 5 │                 0 │
├─────────────────────────┴───────────────────┴───────────────────┤
│ total run duration: 338ms                                       │
├─────────────────────────────────────────────────────────────────┤
│ total data received: 16.93kB (approx)                           │
├─────────────────────────────────────────────────────────────────┤
│ average response time: 62ms [min: 22ms, max: 141ms, s.d.: 55ms] │
└─────────────────────────────────────────────────────────────────┘

Run results should now appear such as below.

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How to Run Collections using Newman

For guide is a reference to some basic Newman codes for execution:

  1. Run a collection only. This can be used if there is no environment or test data file dependency. newman run
  2. Run a collection and environment. The -e indicator is for environment. newman run -e
  3. Run a collection with desired no. of iterations. newman run -n
  4. Run with data file. newman run --data -n -e
  5. Set delay time. This is important as tests may fail if it is run without delay due to requests being started without the previous request completing processing on the endpoint server. newman run -d

Summary