Find GTest via CONFIG mode to reference gmock

[ThomsonTan]

The default module mode for find_package(GTest CONFIG) doesn't include gmock, so switch to CONFIG mode and append imported target GTest::gmock to GTEST_BOTH_LIBRARIES for linking.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #640 (bcb0db9) into main (a947a6e) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #640   +/-   ##
=======================================
  Coverage   94.49%   94.49%           
=======================================
  Files         197      197           
  Lines        9130     9130           
=======================================
  Hits         8627     8627           
  Misses        503      503           

[maxgolov]

Approved. I trust you on this. But if you can also open this in Windows - Visual Studio 2019 (with vcpkg build), that'd be awesome!

Just to confirm it also works well on Windows:

1. tools/setup-buildtools.cmd (preferably in Elevated shell).
2. Then open the main repo dir as "Open -> Directory.." in Visual Studio 2019 with CMake installed.
3. Right-click on CMakeLists.txt to Generate Cache...
4. Then click Build -> Build All... to build all.

We'd probably need to add the vcpkg builds with OTLP enabled to the CI loop, to add automated validation of these changes.

[ThomsonTan]

Approved. I trust you on this. But if you can also open this in Windows - Visual Studio 2019 (with vcpkg build), that'd be awesome!

Just to confirm it also works well on Windows:

1. tools/setup-buildtools.cmd (preferably in Elevated shell).
2. Then open the main repo dir as "Open -> Directory.." in Visual Studio 2019 with CMake installed.
3. Right-click on CMakeLists.txt to Generate Cache...
4. Then click Build -> Build All... to build all.

We'd probably need to add the vcpkg builds with OTLP enabled to the CI loop, to add automated validation of these changes.

Thanks @maxgolov. I validated the VS 2019 build as well which works.

[maxgolov]

@ThomsonTan - I'm still checking, for some reason I get the build building successfully with this change.... but no tests run, at least not in Visual Studio 2019 , all tests show 0 tests run 🤷 I reverted just your change by:

git revert 3ddda

And I got the tests building and running again. Maybe we should add an extra check for if(MSVC) . Let's discuss tomorrow.