add #46 to changelog, and improve API by making optional arguments optional

Author: isaisabel

CHANGELOG.md

@@ -1,3 +1,7 @@
+# Changes staged on develop
+## Improvements
+- Added option to filter mappings by tactic in [technique_mappings_to_csv](technique_mappings_to_csv.py). See pull request [#46](https://github.com/mitre-attack/attack-scripts/pull/46).
+
 # v1.5.2 - 2 September 2020
 ## Improvements
 - Clarified documentation on creation of virtual environments for Windows compatibility.

scripts/technique_mappings_to_csv.py

@@ -23,7 +23,7 @@ def build_taxii_source(collection_name):
     return MemorySource(stix_data=taxii_ds.query())
 
 
-def get_all_techniques(src, source_name, tactic):
+def get_all_techniques(src, source_name, tactic=None):
     """Filters data source by attack-pattern which extracts all ATT&CK Techniques"""
     filters = [
         Filter("type", "=", "attack-pattern"),
@@ -98,7 +98,7 @@ def arg_parse():
     return parser
 
 
-def do_mapping(ds, fieldnames, relationship_type, type_filter, source_name, sorting_keys, tactic):
+def do_mapping(ds, fieldnames, relationship_type, type_filter, source_name, sorting_keys, tactic=None):
     """Main logic to map techniques to mitigations, groups or software"""
     all_attack_patterns = get_all_techniques(ds, source_name, tactic)
     writable_results = []