Newman installation in Postman - Build an Automation Script

Verify Newman installation and version

Preconditions (2)

Step 1: Open the command line interface

Step 2: Run the command 'npm install -g newman' to install Newman globally

Step 3: Wait for the installation to complete

Step 4: Run the command 'newman -v' to check the installed Newman version

✅ Expected Result: Newman installs successfully without errors and the version number is displayed correctly

Automation Requirements - Node.js with child_process module

Assertions Needed:

Verify that 'npm install -g newman' command completes without errors

Verify that 'newman -v' command outputs a valid version string

Best Practices:

Use child_process.exec to run CLI commands asynchronously

Check for errors in command execution

Validate output format with regex for version number

Use clear and descriptive assertion messages

Automated Solution

Postman

import { exec } from 'child_process';

function runCommand(command) {
  return new Promise((resolve, reject) => {
    exec(command, (error, stdout, stderr) => {
      if (error) {
        reject(new Error(`Command failed: ${command}\n${stderr}`));
      } else {
        resolve(stdout.trim());
      }
    });
  });
}

(async () => {
  try {
    console.log('Installing Newman globally...');
    const installOutput = await runCommand('npm install -g newman');
    console.log('Installation output:', installOutput);

    console.log('Checking Newman version...');
    const versionOutput = await runCommand('newman -v');
    console.log('Newman version:', versionOutput);

    const versionRegex = /^\d+\.\d+\.\d+$/;
    if (!versionRegex.test(versionOutput)) {
      throw new Error('Newman version output is not a valid version string');
    }

    console.log('Test passed: Newman installed and version verified successfully.');
  } catch (error) {
    console.error('Test failed:', error.message);
    process.exit(1);
  }
})();

This script uses Node.js child_process.exec to run shell commands asynchronously.

First, it runs npm install -g newman to install Newman globally. It waits for the command to finish and checks for errors.

Next, it runs newman -v to get the installed version. It verifies the output matches a version pattern like 1.2.3.

If any command fails or the version output is invalid, the script throws an error and exits with failure.

This approach ensures the installation and version check are automated and validated properly.

Common Mistakes - 3 Pitfalls

Not checking for errors after running the install command

Assuming the version output is always valid without validation

Running commands synchronously blocking the event loop

Bonus Challenge

Now add data-driven testing to install Newman with different npm versions and verify installation each time

Show Hint

Practice

1. What is the primary purpose of Newman in relation to Postman?

easy

A. To run Postman tests from the command line

B. To create Postman collections

C. To design API endpoints

D. To generate API documentation

Solution

1. Step 1: Understand Newman's role

   Newman is a command-line tool that executes Postman collections outside the Postman app.

2. Step 2: Identify the correct purpose

   Among the options, only running tests from the command line matches Newman's function.

3. Final Answer:

   To run Postman tests from the command line -> Option A

4. Quick Check:

   Newman runs tests = D [OK]

Hint: Newman runs tests outside Postman app [OK]

Common Mistakes:

• Confusing Newman with Postman GUI features
• Thinking Newman creates API endpoints
• Assuming Newman generates documentation

2. Which command correctly installs Newman globally using npm?

easy

A. npm install newman

B. npm install -g newman

C. npm newman install -g

D. install npm -g newman

Solution

1. Step 1: Recall npm global install syntax

   The correct syntax to install a package globally is npm install -g package-name.

2. Step 2: Match the command with Newman

   npm install -g newman matches this syntax exactly for Newman.

3. Final Answer:

   npm install -g newman -> Option B

4. Quick Check:

   Global install uses -g flag = B [OK]

Hint: Global install needs -g flag after install [OK]

Common Mistakes:

• Omitting the -g flag for global install
• Incorrect command word order
• Using 'install npm' instead of 'npm install'

3. After installing Newman globally, what will be the output of the command newman --version if Newman version 5.3.0 is installed?

medium

A. v5.3.0

B. newman version 5.3.0

C. Newman 5.3.0

D. 5.3.0

Solution

1. Step 1: Understand typical npm package version output

   Most npm CLI tools output version without a 'v' prefix, like '5.3.0'. Newman outputs the version number without the 'v'.

2. Step 2: Match expected output format

   Among the options, only '5.3.0' matches the actual output of newman --version.

3. Final Answer:

   5.3.0 -> Option D

4. Quick Check:

   Newman version output does not include 'v' prefix = B [OK]

Hint: Newman version command outputs version without 'v' prefix [OK]

Common Mistakes:

• Expecting full text like 'newman version'
• Assuming 'v' prefix is included
• Confusing output with other commands

4. You ran npm install -g newman but get a 'command not found' error when typing newman --version. What is the most likely cause?

medium

A. The system PATH does not include npm global binaries

B. Node.js is not installed

C. npm cache is corrupted

D. Newman was not installed globally

Solution

1. Step 1: Understand the error context

   The 'command not found' error means the shell cannot find the Newman executable.

2. Step 2: Identify common causes

   Even if Newman is installed globally, if the system PATH does not include npm global binaries folder, the command won't be found.

3. Final Answer:

   The system PATH does not include npm global binaries -> Option A

4. Quick Check:

   PATH missing npm binaries causes command not found [OK]

Hint: Check PATH includes npm global bin folder [OK]

Common Mistakes:

• Assuming Newman was not installed without checking PATH
• Ignoring Node.js installation status
• Blaming npm cache without evidence

5. You want to run a Postman collection named api-tests.postman_collection.json using Newman after installation. Which command correctly runs the collection and saves the report to report.json?

hard

A. newman run api-tests.postman_collection.json -r json > report.json

B. newman api-tests.postman_collection.json --report json --output report.json

C. newman run api-tests.postman_collection.json --reporters json --reporter-json-export report.json

D. newman run api-tests.postman_collection.json --save-report report.json

Solution

1. Step 1: Recall Newman run command syntax

   The correct syntax to run a collection is newman run <collection-file>.

2. Step 2: Identify correct reporter options

   To save a JSON report, use --reporters json --reporter-json-export <file>.

3. Step 3: Match the correct option

   newman run api-tests.postman_collection.json --reporters json --reporter-json-export report.json uses the correct command and reporter flags to save the report as report.json.

4. Final Answer:

   newman run api-tests.postman_collection.json --reporters json --reporter-json-export report.json -> Option C

5. Quick Check:

   Use --reporters and --reporter-json-export for JSON report [OK]

Hint: Use --reporters and --reporter-json-export flags [OK]

Common Mistakes:

• Using shell redirection instead of reporter flags
• Omitting 'run' keyword
• Using incorrect or unsupported flags