Cypress CLI execution - Build an Automation Script

Run Cypress tests using CLI and verify test results

Preconditions (2)

Step 1: Open terminal or command prompt

Step 2: Navigate to the project root folder where Cypress is installed

Step 3: Run the command 'npx cypress run' to execute all tests

Step 4: Observe the terminal output for test execution progress

Step 5: Verify that the test run completes without errors

Step 6: Check the summary in the terminal showing number of tests passed and failed

✅ Expected Result: All Cypress tests run successfully via CLI with a summary showing zero failed tests

Automation Requirements - Cypress

Assertions Needed:

Verify CLI command 'npx cypress run' executes without errors

Verify test summary shows zero failed tests

Best Practices:

Use npm scripts to run Cypress CLI commands

Capture and parse CLI output to assert test results

Run tests in headless mode for CI environments

Automated Solution

Cypress

const { exec } = require('child_process');

describe('Cypress CLI execution test', () => {
  it('should run Cypress tests via CLI and verify no failures', (done) => {
    exec('npx cypress run', (error, stdout, stderr) => {
      if (error) {
        done(error);
        return;
      }

      // Check that output contains 'All specs passed!'
      const allPassed = stdout.includes('All specs passed!') || /\d+ passing/.test(stdout);
      expect(allPassed).to.be.true;

      // Check no failures reported
      const failures = /\d+ failing/.exec(stdout);
      expect(failures).to.be.null;

      done();
    });
  });
});

This test uses Node.js exec to run the Cypress CLI command npx cypress run.

It captures the command output and checks for the text indicating all tests passed and no failures.

Assertions verify the CLI run was successful and no tests failed.

Using done callback ensures the test waits for the CLI command to finish before asserting.

Common Mistakes - 3 Pitfalls

Not waiting for the CLI command to finish before asserting

Hardcoding test output strings that may change

{'mistake': 'Running Cypress GUI instead of headless CLI in automation', 'why_bad': 'GUI requires manual interaction and is not suitable for automated CI runs', 'correct_approach': "Use headless CLI mode with 'npx cypress run' for automation"}

Bonus Challenge

Now add data-driven testing by running Cypress CLI with different environment variables and verify tests pass for each

Show Hint

Practice

1. What does running cypress run from the command line do?

easy

A. Runs all tests in headless mode without opening the Cypress UI

B. Opens the Cypress Test Runner UI for manual test selection

C. Starts a web server for the application under test

D. Generates a test report without executing tests

Solution

1. Step 1: Understand the command cypress run

   This command runs Cypress tests from the command line without opening the UI.

2. Step 2: Identify the mode of execution

   By default, cypress run runs tests in headless mode, meaning no browser window appears.

3. Final Answer:

   Runs all tests in headless mode without opening the Cypress UI -> Option A

4. Quick Check:

   cypress run = headless test run [OK]

Hint: Remember: 'run' means headless test execution [OK]

Common Mistakes:

• Confusing 'cypress run' with 'cypress open'
• Thinking it opens the UI
• Assuming it starts a server

2. Which of the following is the correct syntax to run Cypress tests in Chrome browser using CLI?

easy

A. cypress run --browser chrome

B. cypress open --browser chrome

C. cypress run -b firefox

D. cypress start --browser chrome

Solution

1. Step 1: Identify the correct command to run tests in CLI

   cypress run is used to run tests from CLI, not cypress open or cypress start.

2. Step 2: Check the correct option for specifying browser

   The option to specify browser is --browser, so cypress run --browser chrome is correct syntax.

3. Final Answer:

   cypress run --browser chrome -> Option A

4. Quick Check:

   Use --browser with cypress run [OK]

Hint: Use 'cypress run --browser' to specify browser [OK]

Common Mistakes:

• Using 'cypress open' instead of 'cypress run' for CLI execution
• Using wrong option '-b' instead of '--browser'
• Using non-existent command 'cypress start'

3. What will be the output when running cypress run --spec "cypress/e2e/login.cy.js"?

medium

A. Runs all tests except those in login.cy.js

B. Runs only the tests inside login.cy.js and shows results in terminal

C. Opens Cypress UI and highlights login.cy.js tests

D. Throws an error because --spec is invalid

Solution

1. Step 1: Understand the --spec option

   The --spec option tells Cypress to run only the specified test file(s).

2. Step 2: Analyze the command behavior

   The command runs tests only in cypress/e2e/login.cy.js and outputs results in the terminal because cypress run is headless.

3. Final Answer:

   Runs only the tests inside login.cy.js and shows results in terminal -> Option B

4. Quick Check:

   --spec runs specified test file only [OK]

Hint: Use --spec to run specific test files [OK]

Common Mistakes:

• Thinking it runs all tests except specified file
• Expecting Cypress UI to open with 'run' command
• Assuming --spec is invalid option

4. You run cypress run --browser chrome --headed but tests still run headless. What is the likely cause?

medium

A. Cypress does not support headed mode with Chrome

B. The Chrome browser is not installed on the machine

C. The command must include --headless to run headed

D. The --headed flag is misspelled or missing

Solution

1. Step 1: Understand the --headed flag

   The --headed flag runs tests with the browser UI visible, not headless.

2. Step 2: Identify why tests run headless despite --headed

   The likely cause is that the --headed flag was misspelled (e.g., --headless) or missing from the actual command executed. cypress run defaults to headless mode without the correct flag.

3. Final Answer:

   The --headed flag is misspelled or missing -> Option D

4. Quick Check:

   Missing or misspelled --headed defaults to headless [OK]

Hint: Verify --headed flag spelling and presence when headed mode fails [OK]

Common Mistakes:

• Confusing --headed with --headless
• Assuming Cypress doesn't support headed Chrome
• Ignoring browser installation status

5. You want to run tests only in Firefox, headlessly, and save the results to a JSON file named results.json. Which command achieves this?

hard

A. cypress open --browser firefox --headless --output results.json

B. cypress run --browser firefox --headed --reporter json --output results.json

C. cypress run --browser firefox --headless --reporter json --reporter-options output=results.json

D. cypress run --browser firefox --headless --output results.json

Solution

1. Step 1: Choose correct command and browser

   Use cypress run to run tests headlessly and specify --browser firefox.

2. Step 2: Specify headless mode and JSON reporter output

   Use --headless for no UI, --reporter json to format output, and --reporter-options output=results.json to save results.

3. Final Answer:

   cypress run --browser firefox --headless --reporter json --reporter-options output=results.json -> Option C

4. Quick Check:

   Use reporter options to save JSON results [OK]

Hint: Use --reporter and --reporter-options to save JSON output [OK]

Common Mistakes:

• Using 'cypress open' instead of 'cypress run'
• Missing --reporter or reporter-options flags
• Confusing --headed with --headless