biopython
diff --git a/‎Bio/SeqIO/SnapGeneIO.py‎
Lines changed: 2 additions & 2 deletions b/‎Bio/SeqIO/SnapGeneIO.py‎
Lines changed: 2 additions & 2 deletions
diff --git a/‎Tests/SnapGene/looped_feature.dna‎
10.5 KB b/‎Tests/SnapGene/looped_feature.dna‎
10.5 KB
diff --git a/‎Tests/SnapGene/looped_feature_origin.dna‎
12.5 KB b/‎Tests/SnapGene/looped_feature_origin.dna‎
12.5 KB
diff --git a/‎Tests/test_SeqIO_SnapGene.py‎
Lines changed: 15 additions & 0 deletions b/‎Tests/test_SeqIO_SnapGene.py‎
Lines changed: 15 additions & 0 deletions
@@ -119,7 +119,7 @@ def _parse_location(rangespec, strand, record, is_primer=False):
         # for some reasons
         start += 1
         end += 1
-    if start > end:
+    if start >= end:
         # Range wrapping the end of the sequence
         l1 = SimpleLocation(start, len(record), strand=strand)
         l2 = SimpleLocation(0, end, strand=strand)
@@ -158,7 +158,7 @@ def _parse_features_packet(length, data, record):
             rng = _get_attribute_value(segment, "range")
             n_parts += 1
             next_location = _parse_location(rng, strand, record)
-            if not location:
+            if location is None:
                 location = next_location
             elif strand == -1:
                 # Reverse segments order for reverse-strand features
 
@@ -284,6 +284,21 @@ def test_remove_linebreaks_from_qualifier_values(self):
                     self.assertFalse("\n" in value)
                     self.assertFalse("\r" in value)
 
+    def test_looped_feature(self):
+        """Read a file that has a circular sequence with a feature that spans the entire sequence"""
+
+        # If the feature spans the sequence from start to end
+        record = SeqIO.read("SnapGene/looped_feature_origin.dna", "snapgene")
+        self.assertEqual(record.annotations["topology"], "circular")
+        self.assertEqual(len(record.features), 1)
+        self.assertEqual(str(record.features[0].location), "[0:10](+)")
+
+        # If the feature spans the entire sequence, but starts somewhere in the middle
+        record = SeqIO.read("SnapGene/looped_feature.dna", "snapgene")
+        self.assertEqual(record.annotations["topology"], "circular")
+        self.assertEqual(len(record.features), 1)
+        self.assertEqual(str(record.features[0].location), "join{[2:10](+), [0:2](+)}")
+
 
 class TestCorruptedSnapGene(unittest.TestCase):
     def setUp(self):