# Copyright 2011-2018 Kwant authors.

 #
 # This file is part of Kwant.  It is subject to the license terms in the file
 # LICENSE.rst found in the top-level directory of this distribution and at
 # http://kwant-project.org/license.  A list of Kwant authors can be found in
 # the file AUTHORS.rst at the top-level directory of this distribution and at
 # http://kwant-project.org/authors.
 """Pytest plugin to ignore packages that have uninstalled dependencies.
 
 This ignores packages on test collection, which is required when the
 tests reside in a package that itself requires the dependency to be
 installed.
 """
 
 import importlib
 
 
 # map from subpackage to sequence of dependency module names
 subpackage_dependencies = {

     'kwant/continuum': ['sympy'],
     'kwant/tests/test_qsymm': ['qsymm', 'sympy'],

 }
 
 
 # map from subpackage to sequence of dependency modules that are not installed
 dependencies_not_installed = {}
 for package, dependencies in subpackage_dependencies.items():
     not_installed = []
     for dep in dependencies:
         try:
             importlib.import_module(dep)
         except ImportError:
             not_installed.append(dep)
     if len(not_installed) != 0:
         dependencies_not_installed[package] = not_installed
 
 
 def pytest_ignore_collect(path, config):
     for subpackage, not_installed in dependencies_not_installed.items():
         if subpackage in path.strpath:
             print('ignoring {} because the following dependencies are not '
                   'installed: {}'.format(subpackage, ', '.join(not_installed)))
             return True