A Beginner’s Guide to Playwright Testing with JavaScript: 6 - Why Login Testing Isn’t as Boring as You Think

 Login forms seem simple, but they’re deceptively fragile. A tiny typo in a button’s ID, a misplaced error message, or a password field that doesn’t mask input can turn your app into a user-unfriendly nightmare.

With Playwright, I set out to automate three make-or-break login scenarios. Here’s what broke (a lot), what worked (eventually), and why you should care.

🚀 Scenario 1: When Everything Works (Eventually)

The first thing I wanted to test was the happy path—when a user enters valid credentials, clicks login, and lands where they should.

Sounds simple, right? Well, my first attempt failed spectacularly. Turns out, I forgot to wait for the page to load fully before checking the URL. Rookie mistake. 😅

Fixed Code:

What Broke?

• I wasn’t waiting for the navigation properly.

What Worked?

• await expect(page).toHaveURL(...) ensures the redirect actually happened before the test continues.

✅ Lesson Learned: Just because a button is clicked doesn’t mean the page has changed yet.

🚨 Scenario 2: When Login Fails (And Error Messages Matter)

Next, I wanted to test invalid logins. If a user enters the wrong credentials, the app should clearly tell them what went wrong.

I assumed the error message would show up instantly. Turns out, some apps animate them in with a delay, and my test was checking too soon. 🤦♂️

Fixed Code:

What Broke?

• My test checked for the error before it was visible.

What Worked?

• Playwright waits automatically for elements, but adding explicit expectations helped.

✅ Lesson Learned: Always wait for elements to fully load before asserting their text.

🔒 Scenario 3: The Eye Icon that Didn’t Blink

Ever typed your password in a crowded café and felt paranoid? That’s why login forms mask passwords by default.

Many apps let you toggle password visibility using an eye icon 👁️. My test? Verify that:

1. The password is hidden by default.
2. Clicking the eye icon reveals it.

Here’s the Code:

What Broke?

• The eye icon had a tiny delay before changing the field type.

What Worked?

• Adding await expect(passwordField).toHaveAttribute(...) ensures the test doesn’t check too soon.

✅ Lesson Learned: Tiny UI details matter. Don’t assume things update instantly.

💡 Key Takeaways (A.K.A What I Wish I Knew Earlier)

🔹 Clicking a button ≠ instant navigation. Always verify page transitions properly.

🔹 Error messages don’t always appear instantly. Wait before asserting them.

🔹 UI elements can have small delays. Be patient with expectations.

🎯 What’s Next?

I finally got these tests working (after breaking them a few times first 😆), but I’m excited to explore more. Stay tuned! 🚀

Have you ever struggled with login automation? What’s the weirdest login bug you’ve seen? Let’s chat in the comments! 👇