Better signature for merge_conflicts

umap/tests/test_merge_conflicts.py

@@ -1,3 +1,5 @@
+import pytest
+
 from umap.utils import merge_conflicts
 
 
@@ -48,14 +50,18 @@ def test_removing_same_element():
 
 
 def test_removing_changed_element():
-    assert merge_conflicts(["A", "B"], ["A", "C"], ["A"]) is False
+    with pytest.raises(ValueError):
+        merge_conflicts(["A", "B"], ["A", "C"], ["A"])
 
 
 def test_changing_removed_element():
-    assert merge_conflicts(["A", "B"], ["A"], ["A", "C"]) is False
+    with pytest.raises(ValueError):
+        merge_conflicts(["A", "B"], ["A"], ["A", "C"])
 
 
 def test_changing_same_element():
-    assert merge_conflicts(["A", "B"], ["A", "D"], ["A", "C"]) is False
+    with pytest.raises(ValueError):
+        merge_conflicts(["A", "B"], ["A", "D"], ["A", "C"])
     # Order does not count
-    assert merge_conflicts(["A", "B", "C"], ["B", "D", "A"], ["A", "E", "B"]) is False
+    with pytest.raises(ValueError):
+        merge_conflicts(["A", "B", "C"], ["B", "D", "A"], ["A", "E", "B"])

umap/utils.py

@@ -135,16 +135,14 @@ def merge_conflicts(reference, latest, entrant):
 
     # Now make sure remaining features are still in latest version
     for feature in reference:
-        found = False
         for other in latest:
             if other == feature:
-                found = True
                 break
-        if not found:
+        else:
             # We cannot distinguish the case where both deleted the same
             # element and added others, or where both modified the same
             # element, so let's raise a conflict by caution.
-            return False
+            raise ValueError
 
     # We can merge.
     for feature in reference:

umap/views.py

@@ -804,12 +804,12 @@ def merge(self):
         with open(self.path) as f:
             latest = json.loads(f.read())
 
-        merge = merge_conflicts(
-            reference["features"], latest["features"], entrant["features"]
-        )
-        if merge is False:
-            return merge
-        latest["features"] = merge
+        try:
+            merge_conflicts(
+                reference["features"], latest["features"], entrant["features"]
+            )
+        except ValueError:
+            return False
 
         # Update request data.
         self.request.FILES["geojson"].file = BytesIO(json.dumps(latest).encode("utf-8"))