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You can create an environment variable if you are maintainer of the project by accessing project Settings → CI / CD → Variables
You should restrict DATA_THEOREM_UPLOAD_API_KEY access to protected branch only or at least mask the environment variable
The following gitlab Gitlab CI step can then be used as the upload step:
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You can download a complete example here: https://gitlab.com/marcTranzerdatatheorem/testci-app-upload/-/jobsexample.
This example runs tests on a simple android project, then build builds an apk and finally deploy APK, and then uploads it to Data Theorem Mobile.
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