Merge pull request #16 from gisce/improve-max-min-zero

Return 0 for max/min when an empty sequence

Author: ecarreras

Diff for: ooui/graph/fields.py

@@ -84,8 +84,12 @@ def get_value_for_operator(operator, values):
         avg = total_sum / len(values)
         return round_number(avg)
     elif operator == "min":
+        if not values:
+            return 0
         return min(values)
     elif operator == "max":
+        if not values:
+            return 0
         return max(values)
     else:
         raise ValueError("Unsupported operator: {}".format(operator))

Diff for: spec/graph/fields_spec.py

@@ -122,12 +122,22 @@
             values = [10, 3, 45, 7]
             result = get_value_for_operator('min', values)
             expect(result).to(equal(3))
+        with context('if sequence is empty'):
+            with it('should return 0'):
+                values = []
+                result = get_value_for_operator('min', values)
+                expect(result).to(equal(0))
 
     with context('when operator is "max"'):
         with it('should return the maximum value'):
             values = [10, 3, 45, 7]
             result = get_value_for_operator('max', values)
             expect(result).to(equal(45))
+        with context('if sequence is empty'):
+            with it('should return 0'):
+                values = []
+                result = get_value_for_operator('max', values)
+                expect(result).to(equal(0))
 
     with context('when an unsupported operator is provided'):
         with it('should raise a ValueError'):