tools/compile_and_test_for_board: assert resultdir is valid

[cladmi]

Contribution description

Currently giving an absolute result or outside of RIOT application breaks the
result directory evaluation which can lead to deleting the application.

Add an assertion to detect it.

Testing procedure

tox inside the compile_and_test_for_board directory runs without error.

RIOT/dist/tools/compile_and_test_for_board $ tox

test installed: atomicwrites==1.3.0,attrs==19.1.0,more-itertools==7.0.0,pluggy==0.11.0,py==1.8.0,pytest==4.5.0,six==1.12.0,wcwidth==0.1.7
test run-test-pre: PYTHONHASHSEED='3511953664'
test runtests: commands[0] | pytest -v --doctest-modules
================================================================================================================================== test session starts ===================================================================================================================================
platform linux -- Python 3.6.7, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- /home/harter/work/git/RIOT/dist/tools/compile_and_test_for_board/.tox/test/bin/python
cachedir: .tox/test/.pytest_cache
rootdir: /home/harter/work/git/RIOT/dist/tools/compile_and_test_for_board
collected 3 items                                                                                                                                                                                                                                                                        

compile_and_test_for_board.py::compile_and_test_for_board.is_in_directory PASSED                                                                                                                                                                                                   [ 33%]
compile_and_test_for_board.py::compile_and_test_for_board.list_from_string PASSED                                                                                                                                                                                                  [ 66%]
tests/test_compile_and_test_for_board.py::test_help_message PASSED                                                                                                                                                                                                                 [100%]

================================================================================================================================ 3 passed in 0.08 seconds ================================================================================================================================
lint installed: astroid==2.2.5,isort==4.3.19,lazy-object-proxy==1.4.1,mccabe==0.6.1,pylint==2.3.1,six==1.12.0,typed-ast==1.3.5,wrapt==1.11.1
lint run-test-pre: PYTHONHASHSEED='3511953664'
lint runtests: commands[0] | pylint compile_and_test_for_board.py tests

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

flake8 installed: entrypoints==0.3,flake8==3.7.7,mccabe==0.6.1,pycodestyle==2.5.0,pyflakes==2.1.1
flake8 run-test-pre: PYTHONHASHSEED='3511953664'
flake8 runtests: commands[0] | flake8 compile_and_test_for_board.py tests
________________________________________________________________________________________________________________________________________ summary _________________________________________________________________________________________________________________________________________
  test: commands succeeded
  lint: commands succeeded
  flake8: commands succeeded
  congratulations :)

The error is detected even if the directories do not exist:

./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py . --applications=../relative native

./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py . --applications=../relative native
INFO:native:Saving toolchain
Traceback (most recent call last):
  File "./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py", line 669, in <module>
    main()
  File "./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py", line 646, in main
    for app_dir in app_dirs]
  File "./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py", line 646, in <listcomp>
    for app_dir in app_dirs]
  File "./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py", line 237, in __init__
    "Application result directory is outside main result directory"
AssertionError: Application result directory is outside main result directory

./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py . --applications=/tmp/absolute native

./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py . --applications=/tmp/absolute native
INFO:native:Saving toolchain
Traceback (most recent call last):
  File "./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py", line 669, in <module>
    main()
  File "./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py", line 646, in main
    for app_dir in app_dirs]
  File "./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py", line 646, in <listcomp>
    for app_dir in app_dirs]
  File "./dist/tools/compile_and_test_for_board/compile_and_test_for_board.py", line 237, in __init__
    "Application result directory is outside main result directory"
AssertionError: Application result directory is outside main result directory

Running it with an application outside of RIOT would delete the application as it was deleting the directory content with master.

Issues/PRs references

This was found while working on #10838

[cladmi]

Thank for the review.