Node.js prerequisite in Cypress - Build an Automation Script

Verify Node.js is installed and accessible

Preconditions (2)

Step 1: Open the command line interface

Step 2: Type 'node -v' and press Enter

Step 3: Observe the output version number

✅ Expected Result: The CLI displays the installed Node.js version number starting with 'v', for example, 'v18.15.0'

Automation Requirements - Cypress

Assertions Needed:

Verify the command output contains a valid Node.js version string starting with 'v'

Best Practices:

Use Cypress task to run CLI commands

Assert output using Cypress assertions

Handle asynchronous command execution properly

Automated Solution

Cypress

/// <reference types="cypress" />

// cypress/plugins/index.js
module.exports = (on, config) => {
  on('task', {
    getNodeVersion() {
      const { exec } = require('child_process');
      return new Promise((resolve, reject) => {
        exec('node -v', (error, stdout, stderr) => {
          if (error) {
            return reject(error);
          }
          resolve(stdout.trim());
        });
      });
    }
  });
};

// cypress/e2e/node_version_spec.cy.js
describe('Node.js Prerequisite Check', () => {
  it('should confirm Node.js is installed and version is displayed', () => {
    cy.task('getNodeVersion').then((version) => {
      expect(version).to.match(/^v\d+\.\d+\.\d+$/);
    });
  });
});

This Cypress test uses a task to run the node -v command in the system shell. The task is defined in cypress/plugins/index.js to execute the command asynchronously and return the trimmed output.

In the test file node_version_spec.cy.js, the test calls cy.task('getNodeVersion') to get the Node.js version string. It then asserts that the output matches the pattern vX.Y.Z where X, Y, and Z are numbers, confirming Node.js is installed and accessible.

This approach follows best practices by separating CLI command execution into a task, handling asynchronous code with promises, and using a clear regular expression assertion.

Common Mistakes - 3 Pitfalls

Trying to run CLI commands directly inside Cypress test without using tasks

Not trimming the command output before assertion

{'mistake': "Using a loose assertion like checking if output contains 'v' only", 'why_bad': 'This can pass even if the output is not a valid version string, reducing test reliability.', 'correct_approach': 'Use a regular expression to strictly match the version format <code>vX.Y.Z</code>.'}

Bonus Challenge

Now add data-driven testing to check multiple Node.js commands like 'node -v', 'npm -v', and 'npx -v' for their version outputs.

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