Add some basic unit tests for the file_helper module

Test the 'happy' path of the file_helper.py module
parse_word_list_argument and get_combined_word_lists functions.

Author: diogoosorio

tests/__init__.py

@@ -0,0 +1,42 @@
+import itertools
+import pytest
+import sys
+
+from collections import namedtuple
+from lib.helpers.file_helper import parse_word_list_argument, get_combined_word_lists
+
+WORDLIST_FILES = {
+    'simpsons': ['marge', 'bart', 'homer', 'lisa', 'maggie'],
+    'family_guy': ['stewie', 'lois', 'peter', 'brian', 'maggie', 'chris'],
+    'flinstones': ['fred', 'bambam', 'wilma', 'barney', 'betty'],
+    'duplicates': ['marge', 'bart'],
+}
+
+WordlistFiles = namedtuple('WordlistFiles', 'files words')
+
+@pytest.fixture(scope='session')
+def wordlist(tmpdir_factory):
+    tmpdir = tmpdir_factory.mktemp('wordlists')
+
+    def create_file(filename):
+        file = tmpdir.join(filename)
+        file.write('\n'.join(WORDLIST_FILES[filename]))
+        return str(file)
+
+    words = list(itertools.chain.from_iterable(WORDLIST_FILES.values()))
+    files = [create_file(file) for file in WORDLIST_FILES.keys()]
+
+    return WordlistFiles(files=files, words=words)
+
+def test_parse_word_list_argument(wordlist):
+    argument = ','.join(wordlist.files + ['/non-existing-file'])
+    result = parse_word_list_argument(argument)
+
+    assert wordlist.files == result # non-existing files should be discarded
+
+def test_get_combined_word_lists(wordlist):
+    result = get_combined_word_lists(','.join(wordlist.files))
+
+    assert wordlist.files == result['file_paths']
+    assert wordlist.words == result['words']
+