Add patch implementation for Increment decimal

src/Marten/Patching/IPatchExpression.cs

@@ -81,6 +81,15 @@ public interface IPatchExpression<T>
     /// <returns></returns>
     IPatchExpression<T> Increment(Expression<Func<T, float>> expression, float increment = 1);
 
+    /// <summary>
+    /// Increment a single field or property by adding the increment value
+    /// to the persisted value
+    /// </summary>
+    /// <param name="expression"></param>
+    /// <param name="increment"></param>
+    /// <returns></returns>
+    IPatchExpression<T> Increment(Expression<Func<T, decimal>> expression, decimal increment = 1);
+
     /// <summary>
     /// Append an element to the end of a child collection on the persisted
     /// document

src/Marten/Patching/PatchExpression.cs

@@ -122,6 +122,17 @@ public IPatchExpression<T> Increment(Expression<Func<T, float>> expression, floa
         _patchSet.Add(new PatchData(Items: patch, false));
         return this;
     }
+
+    public IPatchExpression<T> Increment(Expression<Func<T, decimal>> expression, decimal increment = 1)
+    {
+        var patch = new Dictionary<string, object>();
+        patch.Add("type", "increment_float");
+        patch.Add("increment", increment);
+        patch.Add("path", toPath(expression));
+        _patchSet.Add(new PatchData(Items: patch, false));
+        return this;
+    }
+
     //TODO NRT - Annotations are currently inaccurate here due to lack of null guards. Replace with guards in .NET 6+
     public IPatchExpression<T> Append<TElement>(Expression<Func<T, IEnumerable<TElement>>> expression, TElement element)
     {

src/PatchingTests/Patching/PatchExpressionTests.cs

@@ -224,6 +224,36 @@ public void increment_float_with_explicit_interval()
         _expression.Patch["increment"].ShouldBe(5);
     }
 
+    [Fact]
+    public void increment_decimal_with_default()
+    {
+        _expression.Increment(x => x.Decimal);
+
+        _expression.Patch["path"].ShouldBe("Decimal");
+        _expression.Patch["type"].ShouldBe("increment_float");
+        _expression.Patch["increment"].ShouldBe(1);
+    }
+
+    [Fact]
+    public void increment_decimal_with_default_deep()
+    {
+        _expression.Increment(x => x.Inner.Inner.Decimal);
+
+        _expression.Patch["path"].ShouldBe("Inner.Inner.Decimal");
+        _expression.Patch["type"].ShouldBe("increment_float");
+        _expression.Patch["increment"].ShouldBe(1);
+    }
+
+    [Fact]
+    public void increment_decimal_with_explicit_interval()
+    {
+        _expression.Increment(x => x.Decimal, 5);
+
+        _expression.Patch["path"].ShouldBe("Decimal");
+        _expression.Patch["type"].ShouldBe("increment_float");
+        _expression.Patch["increment"].ShouldBe(5);
+    }
+
     [Fact]
     public void append_shallow()
     {

src/PatchingTests/Patching/patching_api.cs

@@ -14,6 +14,7 @@
 using Weasel.Core;
 using Weasel.Postgresql.SqlGeneration;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace PatchingTests.Patching;
 
@@ -264,6 +265,23 @@ public void increment_for_float()
         }
     }
 
+    [Fact]
+    public void increment_for_decimal()
+    {
+        var target = Target.Random();
+        target.Decimal = 11.2m;
+
+        theSession.Store(target);
+        theSession.Patch<Target>(target.Id).Increment(x => x.Decimal, 2.4m);
+        theSession.SaveChanges();
+        theSession.SaveChanges();
+
+        using (var query = theStore.QuerySession())
+        {
+            query.Load<Target>(target.Id).Decimal.ShouldBe(13.6m);
+        }
+    }
+
     [Fact]
     public void append_to_a_primitive_array()
     {