How does the CI know what board it is compiling against? That is usually selected in the Arduino IDE but the CI doesn't know how to do this unless you provide it some information.

The Adafruit Learning System uses a zero length file to test and see which microcontroller board it should run the tests on. This takes the form .xxxxx.test.only where xxxxx is a code for the board to test against.

The most current list of test boards is found in the file below on line 10:

If a microcontroller is not listed, then you should contact your Adafruit Learning System facilitator for assistance


If you have an Adafruit Circuit Playground Express, you look in the file and there is a listing for "cpx_ada". Use that one.

Using your editor, make a file (contents irrelevant, zero length or just a space are fine). Name the file .cpx_ada.text.only and include it in the directory with the .ino file for the project.

If you have examples for multiple microcontroller boards, put each example in it's own subdirectory with an appropriate .test.only file.

What if I don't do this?

The CI will look at the files and not know what board to use in the Arduino IDE run and will give errors as it tries everything. Your submission will not pass and your facilitator will ask you to include the correct .test.only file. You may ask the facilitator to do it for you but you know your project, it's expected you do this yourself.

This guide was first published on Oct 19, 2021. It was last updated on Oct 19, 2021.

This page (Adding a .test.only file) was last updated on Dec 01, 2021.

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