I'm trying to move this project from the web config interface to using .readthedocs.yaml, I've added the config file and configured it to do a pip install .[build] before running Sphinx.
I've had this work great with new projects of mine and really like it, but testfixtures is one of my oldest projects and seems to ignore the .readthedocs.yaml that I added in https://github.com/Simplistix/testfixtures/commit/5b0857f125d15a5f4b5b120bede6e0e1934f7ebc. Looking at the build log, I don't see the pip install .[build] I've configured.
I'm going to investigate a little more here, at first sight seems like you have a valid config file.
I think there is a syntax error here
The indentation is wrong.
But instead of showing that error to the user, we are defaulting to create our own config file, I think showing the error should be the way to go, instead of trying to fix it magically.
Ah, nice spot! Yes, showing the error would definitely save lots of work all round :-)
I'm going to fix the bug around not showing the correct message to the user, but fixing the indentation should make your project pass.
yaml fix worked, thanks: https://readthedocs.org/projects/testfixtures/builds/8786855/