
currently an invalid collection will error out on docs sanity, but this is misleading since the problem is that the collection name itself is invalid, a previous test verifying this should be introduced to avoid confusion.

example currently:
```
Running sanity test 'ansible-doc' with Python 3.7
ERROR: Command "ansible-doc -t module cyberark.ansible-security-automation-collection.cyberark_account cyberark.ansible-security-automation-collection.cyberark_authentication cyberark.ansible-security-automation-collection.cyberark_credential cyberark.ansible-security-automation-collection.cyberark_user" returned exit status 250.
>>> Standard Error
[WARNING]: module cyberark.ansible-security-automation-collection.cyberark_account not found in: /dev/null:/home/abehl/work/src/anshul_ansible/ansible/lib/ansible/modules
ERROR! Unexpected Exception, this is probably a bug: cannot unpack non-iterable NoneType object
```
##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
ansible-test

"""Return the provided dictionary with any None values excluded."""
    return dict((key, value) for key, value in data.items() if value is not None)
def find_executable(executable, cwd=None, path=None, required=True):  
    """
    Find the specified executable and return the full path, or None if it could not be found.
    If required is True an exception will be raised if the executable is not found.
    If required is set to 'warning' then a warning will be shown if the executable is not found.
    """
    match = None
    real_cwd = os.getcwd()
    if not cwd:
        cwd = real_cwd
    if os.path.dirname(executable):
        target = os.path.join(cwd, executable)
        if os.path.exists(target) and os.access(target, os.F_OK | os.X_OK):
            match = executable
    else:
        if path is None:
            path = os.environ.get('PATH', os.path.defpath)
        if path:
            path_dirs = path.split(os.path.pathsep)
            seen_dirs = set()