iceoryx_posh_testing cannot find iceoryx_hoofs_testing in CMake

[dkroenke]

Required information

Operating system:
Ubuntu 20.04 LTS
CMake version 3.16.3

Observed result or behaviour:
the following warning comes up when building iceoryx with tests enabled:

CMake Warning at iceoryx/iceoryx_posh/CMakeLists.txt:306 (find_package):
  By not providing "Findiceroyx_hoofs_testing.cmake" in CMAKE_MODULE_PATH
  this project has asked CMake to find a package configuration file provided
  by "iceroyx_hoofs_testing", but CMake did not find one.

  Could not find a package configuration file provided by
  "iceroyx_hoofs_testing" with any of the following names:

    iceroyx_hoofs_testingConfig.cmake
    iceroyx_hoofs_testing-config.cmake

  Add the installation prefix of "iceroyx_hoofs_testing" to CMAKE_PREFIX_PATH
  or set "iceroyx_hoofs_testing_DIR" to a directory containing one of the
  above files.  If "iceroyx_hoofs_testing" provides a separate development
  package or SDK, be sure it has been installed.


-- The package 'iceoryx_posh_testing' is used in source code version.
-- The package 'iceoryx_posh' is used in source code version.

With that, the iceoryx_posh_testing lib cannot find the hoofs testing lib properly and becomes unusable without it.

This can be mitigated by setting the following:

set(iceroyx_hoofs_testing_DIR path/to/installed/iceoryx/lib/cmake)
find_package(iceoryx_hoofs_testing REQUIRED)

In the CMake file where you want to use iceoryx_posh_testing before the find_package call for it.

Expected result or behaviour:
iceoryx_hoofs_testing needs to be a required dependency to iceoryx_posh_testing to ensure correct linking between both libraries.

Conditions where it occurred / Performed steps:
Cmake build with tests enabled.