pickle-depickle tfidf test now represents different executions (#223)

WordAnalyser reset between calls to main() - will catch if stopwords
etc not populated

tests/test_pygrams.py

@@ -8,6 +8,7 @@
 
 import pygrams
 from scripts import FilePaths
+from scripts.text_processing import WordAnalyzer
 from scripts.utils.pygrams_exception import PygramsException
 
 
@@ -227,6 +228,13 @@ def test_simple_output_tfidf_pickle_and_unpickle(self, mock_path_isfile, mock_ou
         args = ['-ds', self.data_source_name, '--date_header', 'publication_date', '--max_document_frequency', '1.0']
         pygrams.main(args)
 
+        # reset static object
+        WordAnalyzer.tokenizer = None
+        WordAnalyzer.preprocess = None
+        WordAnalyzer.ngram_range = None
+        WordAnalyzer.stemmed_stop_word_set_n = None
+        WordAnalyzer.stemmed_stop_word_set_uni = None
+
         # Fail if original data frame is requested from disc
         def factory_read_pickle_fake(pickle_file_name):
             self.fail(f'Should not be reading {pickle_file_name} via a factory if TFIDF was requested from pickle')