Abort if test definitions exist but no tests were actually
constructed from the configuration.

This can happen if the regex does not match any of the files
in the reference solutions directory.

Lars Bilke authored 4 years ago and Dmitri Naumov committed 4 years ago

Can be used inside a project file similar to the glob expression
in AddTest() (CMake). If the regex-parameter is present, the `file`-
parameter is ignored and can be omitted.

The fmt library happily accepts std::string without
any conversions.

Pass the value directly instead and only check if the string
convertible to a double if not empty.

This avoids possible losses due to conversion.

Add --reference PATH option to ogs, which when present
will execute tests (vtkdiff) constructed from the
<test_definiton> section in the project file.
This section contains the tester (vtkdiff for now)
the file, field, and absolute and relative tolerances.

This allows the user to run tests w/o cmake and includes
the previously separated test description into the
project file.