BDD & Gherkin for Automation Engineers

1 The Hook — Why This Matters

An Auckland fintech is building a login feature with a "remember me" checkbox. Developers implement it to persist a session cookie for 30 days. QA tests it by checking that the cookie exists after login. Product described it in Jira as "users should stay logged in across browser restarts."

Three teams. Three different interpretations. When QA finds the session doesn't survive a browser restart (which it doesn't, because the developer stored it in session storage rather than a persistent cookie), it's escalated as a bug — but the developer says they met the spec, and product isn't sure who is right.

A Three Amigos session using Gherkin would have surfaced this ambiguity before a single line of code was written. The word "remember" would have required a precise Gherkin scenario. Precisely what event triggers persistence? How long? What clears it? Everyone signs off on the Gherkin before development begins. No surprises at the end.

2 The Rule — The One-Sentence Version

When you write Gherkin, you are not writing tests. You are writing a specification in plain English that happens to be executable. If the Three Amigos can't agree on the Gherkin wording, you have found an ambiguity before it becomes a defect.

3 The Analogy — Think Of It Like...

4 Watch Me Do It — Step by Step

Here is a complete Gherkin feature file for a NZ e-commerce login, followed by the Playwright + Cucumber step definitions that wire the scenarios to real browser automation.

Feature: Customer Login
  As a returning NZ customer
  I want to log in with my email and password
  So that I can view my order history

  Scenario: Successful login redirects to dashboard
    Given I am on the Resync Store login page
    And I have a registered account with email "kiri@example.co.nz"
    When I enter my email "kiri@example.co.nz" and password "ValidPass123!"
    And I click the "Log in" button
    Then I should be redirected to the dashboard
    And I should see the message "Welcome back, Kiri"

  Scenario: Invalid password shows error
    Given I am on the Resync Store login page
    When I enter my email "kiri@example.co.nz" and password "WrongPass!"
    And I click the "Log in" button
    Then I should see an error message "Invalid email or password"
    And I should remain on the login page

import { Given, When, Then } from '@cucumber/cucumber';
import { expect } from '@playwright/test';

Given('I am on the Resync Store login page', async function () {
  await this.page.goto('/login');
});

When('I enter my email {string} and password {string}',
  async function (email: string, password: string) {
    await this.page.getByLabel('Email address').fill(email);
    await this.page.getByLabel('Password').fill(password);
  }
);

When('I click the {string} button', async function (buttonName: string) {
  await this.page.getByRole('button', { name: buttonName }).click();
});

Then('I should be redirected to the dashboard', async function () {
  await expect(this.page).toHaveURL(/.*dashboard/);
});

Then('I should see the message {string}', async function (msg: string) {
  await expect(this.page.getByText(msg)).toBeVisible();
});

Then('I should see an error message {string}', async function (msg: string) {
  await expect(this.page.getByRole('alert')).toContainText(msg);
});

Then('I should remain on the login page', async function () {
  await expect(this.page).toHaveURL(/.*login/);
});

5 When to Use It / When NOT to Use It

6 Common Mistakes — Don't Do This

7 Now You Try — Prompt Lab

Write your Gherkin feature file below, then send it to the AI coach for review.

8 Self-Check — Can You Actually Do This?

Click each question to reveal the answer. Three from three means you're ready for the interview round.

9 Interview Prep — What They'll Ask

10 Next Step

You can now write Gherkin scenarios and wire them to Playwright with Cucumber. The next module covers catching visual regressions automatically — layout shifts, colour changes, and rendering bugs that functional tests miss entirely.