Added comment in test files

Author: sujata-m

tests/unit_tests/test_roundtrip/test_roundtrip.py

@@ -4,12 +4,13 @@
 import xml.etree.ElementTree as ET
 from src.osm_osw_reformatter import Formatter
 
+# Paths to test files and output directory
 ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 OUTPUT_DIR = os.path.join(os.path.dirname(os.path.dirname(ROOT_DIR)), 'output')
 TEST_ZIP_FILE = os.path.join(ROOT_DIR, 'test_files/test_roundtrip.zip')
 TEST_XML_FILE = os.path.join(ROOT_DIR, 'test_files/test_roundtrip.xml')
 
-
+### Helper to parse OSM XML and return all node and way elements ###
 def parse_osm_file(xml_path):
     tree = ET.parse(xml_path)
     root = tree.getroot()
@@ -22,8 +23,8 @@ def parse_osm_file(xml_path):
             ways.append(elem)
     return nodes, ways
 
+### Extract all ext:* tags (as (k,v) pairs) from a list of OSM XML elements ###
 def extract_ext_tags(elems):
-    """Extract all ext:* tags from a list of XML elements."""
     ext_tags = set()
     for elem in elems:
         for tag in elem.findall("tag"):
@@ -33,6 +34,7 @@ def extract_ext_tags(elems):
                 ext_tags.add((k, v))
     return ext_tags
 
+### Utility: Given filepaths, bundle them into a zip for input to the formatter ###
 def generate_zip(filepaths):
     zip_path = f'{OUTPUT_DIR}/first_roundtrip_geojson.zip'
     with zipfile.ZipFile(zip_path, 'w', zipfile.ZIP_DEFLATED) as zipf:
@@ -41,9 +43,16 @@ def generate_zip(filepaths):
             zipf.write(filepath, arcname)
     return zip_path
 
+################################################################################
+# Test 1: Full roundtrip starting from an OSW zip file
+# This checks that all ext:* tags in the original OSM XML are preserved after:
+# OSW zip → OSM XML → OSW (GeoJSON) → OSM XML
+################################################################################
+
 class TestRoundTrip(unittest.IsolatedAsyncioTestCase):
 
     def setUp(self):
+        # Start with a zipped OSW input, convert to OSM XML
         self.formatter = Formatter(workdir=OUTPUT_DIR, file_path=TEST_ZIP_FILE, prefix='test_roundtrip')
         convert = self.formatter.osw2osm()
         self.generated_osm_file = convert.generated_files
@@ -52,15 +61,12 @@ def setUp(self):
     def tearDown(self):
         self.formatter.cleanup()
 
+    ### Compares ext:* tags in two OSM XML files ###
     def compare_osm_files(self, file1, file2):
         nodes1, ways1 = parse_osm_file(file1)
         nodes2, ways2 = parse_osm_file(file2)
-
-        # Get all ext:* tags from both files
         ext_tags1 = extract_ext_tags(nodes1) | extract_ext_tags(ways1)
         ext_tags2 = extract_ext_tags(nodes2) | extract_ext_tags(ways2)
-
-        # Check all tags in file1 are present in file2
         missing_ext_tags = ext_tags1 - ext_tags2
 
         if missing_ext_tags:
@@ -72,7 +78,7 @@ def compare_osm_files(self, file1, file2):
         )
 
     async def test_roundtrip(self):
-        # First roundtrip: OSW -> OSM XML -> OSW (GeoJSON) -> OSM XML
+        # OSM XML → OSW (GeoJSON) → zip → OSM XML
         formatter = Formatter(workdir=OUTPUT_DIR, file_path=self.generated_osm_file, prefix='first_roundtrip_geojson')
         result = await formatter.osm2osw()
         generated_files = result.generated_files
@@ -83,20 +89,20 @@ async def test_roundtrip(self):
         generated_osm_file = convert.generated_files
 
         self.compare_osm_files(self.generated_osm_file, generated_osm_file)
-
         formatter.cleanup()
 
+################################################################################
+# Test 2: Full roundtrip starting from a plain OSM XML file (not zipped OSW)
+# This is useful to ensure ext:* tags are preserved in a slightly different flow
+################################################################################
+
 class TestXMLRoundTrip(unittest.IsolatedAsyncioTestCase):
 
     def compare_osm_files(self, file1, file2):
         nodes1, ways1 = parse_osm_file(file1)
         nodes2, ways2 = parse_osm_file(file2)
-
-        # Get all ext:* tags from both files
         ext_tags1 = extract_ext_tags(nodes1) | extract_ext_tags(ways1)
         ext_tags2 = extract_ext_tags(nodes2) | extract_ext_tags(ways2)
-
-        # Check all tags in file1 are present in file2
         missing_ext_tags = ext_tags1 - ext_tags2
 
         if missing_ext_tags:
@@ -108,6 +114,7 @@ def compare_osm_files(self, file1, file2):
         )
 
     async def test_xml_roundtrip(self):
+        # Start from OSM XML → OSW (GeoJSON) → zip → OSM XML
         formatter = Formatter(workdir=OUTPUT_DIR, file_path=TEST_XML_FILE, prefix='first_roundtrip_geojson')
         result = await formatter.osm2osw()
         generated_files = result.generated_files
@@ -120,3 +127,5 @@ async def test_xml_roundtrip(self):
         self.compare_osm_files(TEST_XML_FILE, generated_osm_file)
         formatter.cleanup()
 
+################################################################################
+