The behavior differs by platform and if the variable is already set.
Encode existing behavior in tests to preserve it until intentionally
changed.
Issue: #27285
Add the support of CACHE{variable} syntax to enable:
* better consistency with other commands which use this syntax
* more flexibility regarding cache variable options
For policy-specific tests, use the version before the policy was
introduced. Otherwise, use 3.5 where possible.
Also, remove `cmake_minimum_required()` and `project()` calls from
individual cases where they are handled by `CMakeLists.txt`.
* parent-scope-tests:
test: add a test for PARENT_SCOPE with multiple scopes
test: add test for PARENT_SCOPE behavior
Conflicts:
Tests/RunCMake/set/RunCMakeTest.cmake
This will allow decoupling the name of the test from the name and
location of the source file under test, which means one source
file can be used for multiple tests.
Rename the PARENT_SCOPE test in RunCMake.set to not use a keyword
of the if() command as a file name. As the filename is now used
with an if condition, this causes a conflict.
