Error on no tests in CTest

[awvwgk]

We are currently pinning CMake to version 3.16 in our CI, which doesn't allow to raise an error in case CTest doesn't find any tests. Unless there is a particular reason to test with CMake 3.16, we can use this PR to use the preinstalled CMake 3.22 version.

Closes #587

[jvdp1]

LGTM.
I believe @certik wrote the install_cmake.sh, but I can't remember the reason. @certik, what was the aim of this (if it is actually you who did this)?

[awvwgk]

I thought it was used to test the oldest supported CMake version, but the minimum required CMake version is 3.14. Maybe the original Ubuntu image 16.04 or 18.04 did not have a sufficiently new CMake version preinstalled?

[jvdp1]

I thought it was used to test the oldest supported CMake version, but the minimum required CMake version is 3.14. Maybe the original Ubuntu image 16.04 or 18.04 did not have a sufficiently new CMake version preinstalled?

Yes, it could be that.

[LKedward]

I assume the CMake version was pinned to ensure that there were no breaking changes for the minimum required version, but I can't be sure. The changes to the CI all look fine to me. What is the motivation here? i.e. what situation would cause CMake to not find any tests?

[jvdp1]

i.e. what situation would cause CMake to not find any tests?

I have no idea why CMake didn't find the tests. I observed it for several actions, and then seemed to work fine again...

[jvdp1]

Two approvals... I'll merge this PR. Thank you @awvwgk