Sleeping Better at Night: Automating Trust in Your SaaS
TL;DR
Manual regression testing is a nightmare. We implemented Playwright E2E tests to act as a 'Robot User' that verifies our critical billing and authentication flows 24/7.
As developers, we often fear the "Friday Deploy." You push a small CSS fix, and suddenly, your billing page stops working. No one notices until Monday, and you've lost a weekend's worth of revenue.
This week, I decided to stop crossing my fingers and start automating trust. I added End-to-End (E2E) Testing to my application. Here is what I learned.
What is E2E Testing? (The "Robot User")
Unit tests check if a function works (2 + 2 = 4). E2E tests check if the application works.
Think of an E2E test as a Robot User. It opens a real browser, clicks real buttons, and expects real things to happen. If the Robot can't log in, neither can your users.
The Tool: Playwright
I chose Playwright because it's fast, modern, and handles the "flakiness" of the web (like waiting for pages to load) automatically.
The Challenge: "Login" isn't simple
My first test seemed simple: Go to Login -> See 'Welcome'.
But it failed. Why? Because I told the robot to look for "a header" (<h2>).
My page had two headers. The robot got confused and crashed.
Lesson: Be specific. I changed the instruction to: "Look for a Heading with the name 'Welcome back'." It worked instantly. Tests need to be as precise as they are dumb.
The "Security Guard" Test
One of the most valuable tests I wrote wasn't about logging in it was about keeping people out.
I told the robot: "Try to go to the Billing Page directly." Since the robot didn't have a password, the app correctly kicked it back to the Login page.
This is a simple test, but it guarantees that my protection logic is active. If I ever accidentally break my authentication code, this test will scream at me before a single user exposes their data.
Why This Matters
It took me about an hour to set this up. In exchange, I now have a command: "npm run test:e2e"
Every time I run it, I know:
- My site is up.
- My login page works.
- My security redirects are active.
That assurance is worth more than any new feature I could have built in that hour.