Firebase Device Test lab: Failed to create a test matrix

Go here https://console.developers.google.com/apis/api/testing.googleapis.com/overview

select the project that you are using to run tests with Test Lab, and click "Enable".

I had exactly the same problem and I check all the suggested solutions, like give admin rights, enable the testing API and it didn't work.

Lastly, I tried creating the tests from Android Studio. From Android Studio, go to Tools menu, then Firebase. I just followed the assistant and voilà, tests are running now!.

Ahmed here from the Firebase Test Lab team.

The issue happens when you exceed the quota for the day. There have been two issues on the Test Lab side contributing to the confusion here:

1. The message shown is confusing and it's hard to understand what's going on
2. To enforce this daily quota on usage, we require to have the API enabled on your project. We needed to have the API enabled on all Firebase projects. When we launched, we had the following in place (i) All new projects have the API enabled by default and (ii) All existing Firebase Test Lab users had the API backfilled. The issue happens when you have created a Firebase project in the past (before October 1st 2016) and never used Test Lab then went back to use it afterwards.

Issue (1) is still ongoing and we're currently working on making our error messages more informative. Stay tuned!

Issue (2) is now resolved completely. We've backfilled all the Firebase projects that were ever created with the Test Lab APIs.

You should now expect seeing this issue only in cases where you exceed the daily quota till we provide a better error message.

Thanks so much and apologies for the confusion!

Sorry for the confusion. We are improving this error message moving forward.

The problem is that you don't have the Google Cloud Testing API enabled for your project. Please can you do that?

Or just create a new project for which it will be automatically enabled.