Start with a big jump.

Qowaiv · Mar 10, 2024 · cc3e25a · cc3e25a
1 parent 1cfaf58
commit cc3e25a
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Showing 2 changed files with 6 additions and 4 deletions.
diff --git a/specs/Qowaiv.Specs/Month_span_specs.cs b/specs/Qowaiv.Specs/Month_span_specs.cs
@@ -92,6 +92,7 @@ public void decrement()
 
 public class Can_subtract
 {
+    [TestCase("2020-04-30", "1710-02-01", "310Y+2M")]
     [TestCase("2020-04-30", "2020-04-01", 00)]
     [TestCase("2020-04-30", "2020-03-31", 01)]
     [TestCase("2020-01-01", "2019-01-02", 11)]
@@ -102,6 +103,7 @@ public void two_dates(Date d1, Date d2, MonthSpan expected)
         => MonthSpan.Subtract(d1, d2).Should().Be(expected);
 
 #if NET6_0_OR_GREATER
+    [TestCase("2020-04-30", "1710-02-01", "310Y+2M")]
     [TestCase("2020-04-30", "2020-04-01", 00)]
     [TestCase("2020-04-30", "2020-03-31", 01)]
     [TestCase("2020-01-01", "2019-01-02", 11)]

diff --git a/src/Qowaiv/MonthSpan.cs b/src/Qowaiv/MonthSpan.cs
@@ -332,13 +332,13 @@ public static MonthSpan Subtract(Date d1, Date d2)
 
         if (negative)
         {
-            max = d2;
-            min = d1;
+            (min, max) = (max, min);
         }
 
-        var test = min;
+        var years = Math.Max(0, max.Year - min.Year - 1);
+        var months = years * 12;
 
-        var months = 0;
+        var test = min.AddYears(years);
 
         while (test < max)
         {