Add tests for SVG output in glycosylation process

Extended the `test_cglycosylation` function to include assertions for SNFG output validation. Introduced XML parsing to check SVG structure, ensuring specific elements and attributes are present.

package/tests/test_glycosylation.py

@@ -1,4 +1,7 @@
 from pathlib import Path
+from pprint import pprint
+import xml.etree.ElementTree as ET
+
 import gemmi
 import sails
 import pytest
@@ -20,13 +23,16 @@ def cglycan(data_base_path):
 
 
 def test_cglycosylation(cglycan):
-    s, m, l = sails.glycosylate(*cglycan)
+    s, m, l, snfgs = sails.glycosylate(*cglycan)
     assert s
     assert m
     assert l
+    assert snfgs
+
     assert isinstance(s, gemmi.Structure)
     assert isinstance(m, gemmi.Mtz)
 
+    # test log file
     assert 'cycles' in l
     assert 'date' in l
 
@@ -59,5 +65,28 @@ def test_cglycosylation(cglycan):
     assert rsr_score > 0.9
     assert dds_score < 0.75
 
+    # test snfg output
+    assert 1 in snfgs
+    c1 = snfgs[1]
+    expected_trp_key = "C-TRP-16"
+    assert expected_trp_key in c1
+
+    root = ET.fromstring(c1[expected_trp_key])
+    assert root.tag == '{http://www.w3.org/2000/svg}svg'
+    assert root.attrib['width'] == '1200'
+    assert root.attrib['height'] == '800'
+
+    line_count = len(root.findall('{http://www.w3.org/2000/svg}line'))
+    rect_count = len(root.findall('{http://www.w3.org/2000/svg}rect'))
+    circle_count = len(root.findall('{http://www.w3.org/2000/svg}circle'))
+    text_count = len(root.findall('{http://www.w3.org/2000/svg}text'))
+    tspan_count = len(root.findall('.//{http://www.w3.org/2000/svg}tspan'))
+
+    # Assert the expected counts
+    assert line_count == 3, f"Expected 3 <line> elements, but found {line_count}"
+    assert rect_count == 1, f"Expected 1 <rect> element, but found {rect_count}"
+    assert circle_count == 1, f"Expected 1 <circle> element, but found {circle_count}"
+    assert text_count == 3, f"Expected 3 <text> elements, but found {text_count}"
+    assert tspan_count == 1, f"Expected 1 <tspan> element, but found {tspan_count}"