The Green Illusion
There is a specific kind of arrogance that comes from a green CI pipeline. When you see 10,482 tests pass, you feel invincible. "The system is logical," you think. "It is proven."
Last Tuesday, we shipped unsafe code. It wasn't a syntax error. It wasn't a logic error in a function. It was a state error that our tests were specifically designed to ignore.
The Mocking Trap
To make our tests fast, we mocked everything. We mocked the database. We mocked the payment gateway. We mocked the user session service.
Our tests proved one thing: That our code works perfectly with our mocks.
The bug happened in the seam between the services. The real User Service returned a 403 Forbidden in a specific edge case. Our mock, written 2 years ago, assumed it would return 401 Unauthorized.
Our code handled the 401 perfectly. It choked on the 403. Our 10,000 tests were verifying a fantasy world that no longer existed.
The Cost of "Flaky" Tests
We had "flaky" E2E tests. You know the ones. They fail 10% of the time because of a timing issue. So we put retries: 3 in our Playwright config.
Retries are a lie. A test that fails once and passes twice is a failing test that got lucky. We normalized failure. We taught the team that "Red" doesn't mean "Stop," it means "Roll the dice again."
The bug that hit production had actually failed the test suite once. But the retry logic hid it. The silence of the logs was deafening.
Quantity vs. Quality
We had optimized for Code Coverage. We should have optimized for Use Case Coverage.
We had 500 tests checking if a React button rendered the correct shade of blue. We had 0 tests checking what happened if the user clicked that button while the internet connection was flaky.
We had built a test suite for the compiler, not for the customer.
The "Delete Tests" Day
After the incident, we did something radical. We evaluated every test suite based on "Value Provided."
If a test hadn't caught a bug in 2 years, we deleted it. If a test mocked more than 2 layers of dependencies, we deleted it.
We deleted 4,000 tests. Our build time went from 4 hours to 45 minutes.
And strangely, our confidence went up. Because now, when a test fails, we know it's real. We stopped ignoring the noise because we removed the noise.
Conclusion
A test suite is not a security blanket. It's a tool. If your tool is dull, heavy, and lies to you, throw it away. 100 meaningful tests are worth more than 10,000 green checkboxes.
Written by XQA Team
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