Fix for grouping Merge2 + added corresponding test (#237)

Author: b0bi79

ClosedXML.Report/Excel/Subtotal.cs

@@ -308,21 +308,29 @@ public SubtotalGroup[] ScanForGroups(int groupBy)
 
                 var groupRng = Sheet.Range(moveData.SourceAddress);
 
-                var cuttingGroups = _groups.Where(g => moveData.SourceAddress.Contains(g.Range.RangeAddress.LastAddress)).ToArray();
+                var cuttingGroups = _groups.Select(g => g.Range.RangeAddress.LastAddress)
+                    .Distinct()
+                    .Where(address => moveData.SourceAddress.Contains(address))
+                    .OrderBy(address => address.RowNumber)
+                    .ToArray();
                 if (cuttingGroups.Any())
                 {
                     var startAddress = moveData.SourceAddress.FirstAddress;
                     foreach (var g in cuttingGroups)
                     {
-                        groupRng = Sheet.Range(startAddress, g.Range.RangeAddress.LastAddress);
+                        groupRng = Sheet.Range(startAddress, g);
                         result.Add(new SubtotalGroup(level, groupBy, moveData.GroupTitle, groupRng, null, false));
-                        startAddress = g.Range.LastCell().WorksheetRow().RowBelow()
+                        startAddress = Sheet.Cell(g).WorksheetRow().RowBelow()
                             .Cell(startAddress.ColumnNumber).Address;
                     }
-                    groupRng = Sheet.Range(startAddress, moveData.SourceAddress.LastAddress);
+
+                    groupRng = startAddress.RowNumber <= moveData.SourceAddress.LastAddress.RowNumber
+                        ? Sheet.Range(startAddress, moveData.SourceAddress.LastAddress)
+                        : null;
                 }
 
-                result.Add(new SubtotalGroup(level, groupBy, moveData.GroupTitle, groupRng, null, false));
+                if (groupRng != null)
+                    result.Add(new SubtotalGroup(level, groupBy, moveData.GroupTitle, groupRng, null, false));
             }
 
             _groups.AddRange(result);

tests/ClosedXML.Report.Tests/SubtotalTests.cs

@@ -57,22 +57,59 @@ public void SummaryAbove()
         [Fact]
         public void ScanForGroupsTest()
         {
-            LoadTemplate("9_plaindata.xlsx");
+            void AssertGroup(SubtotalGroup group, string expectedAddress, string expectedTitle)
+            {
+                group.Range.RangeAddress.ToString().Should().Be(expectedAddress);
+                group.Level.Should().Be(1);
+                group.GroupTitle.Should().Be(expectedTitle);
+            }
+
+            _workbook = new XLWorkbook();
+            var sheet = _workbook.AddWorksheet("test");
+            sheet.Range("A2:A5").Value = "val1";
+            sheet.Range("A6:A9").Value = "val2";
+            sheet.Range("A10:A13").Value = "val3";
+
+            sheet.Range("B2:B4").Value = "val4";
+            sheet.Range("B5:B11").Value = "val5";
+            sheet.Range("B12:B13").Value = "val6";
+
+            sheet.Range("C2:C3").Value = "val7";
+            sheet.Range("C4:C6").Value = "val8";
+            sheet.Range("C7:C8").Value = "val9";
+            sheet.Range("C9:C12").Value = "val7";
+            sheet.Range("C13:C13").Value = "val8";
+
+            _rng = sheet.Range("A2:C13");
 
-            SubtotalGroup[] groups;
             using (var subtotal = new Subtotal(_rng))
+            {
+                var groups = subtotal.ScanForGroups(1);
+                groups.Length.Should().Be(3);
+                AssertGroup(groups[0], "A2:C5", "val1");
+                AssertGroup(groups[1], "A6:C9", "val2");
+                AssertGroup(groups[2], "A10:C13", "val3");
+
                 groups = subtotal.ScanForGroups(2);
+                groups.Length.Should().Be(5);
+                AssertGroup(groups[0], "A2:C4", "val4");
+                AssertGroup(groups[1], "A5:C5", "val5");
+                AssertGroup(groups[2], "A6:C9", "val5");
+                AssertGroup(groups[3], "A10:C11", "val5");
+                AssertGroup(groups[4], "A12:C13", "val6");
 
-            groups.Length.Should().Be(3);
-            groups[0].Range.RangeAddress.ToString().Should().Be("C3:I26");
-            groups[0].Level.Should().Be(1);
-            groups[0].GroupTitle.Should().Be("Central");
-            groups[1].Range.RangeAddress.ToString().Should().Be("C27:I38");
-            groups[1].Level.Should().Be(1);
-            groups[1].GroupTitle.Should().Be("East");
-            groups[2].Range.RangeAddress.ToString().Should().Be("C39:I44");
-            groups[2].Level.Should().Be(1);
-            groups[2].GroupTitle.Should().Be("West");
+                groups = subtotal.ScanForGroups(3);
+                groups.Length.Should().Be(9);
+                AssertGroup(groups[0], "A2:C3", "val7");
+                AssertGroup(groups[1], "A4:C4", "val8");
+                AssertGroup(groups[2], "A5:C5", "val8");
+                AssertGroup(groups[3], "A6:C6", "val8");
+                AssertGroup(groups[4], "A7:C8", "val9");
+                AssertGroup(groups[5], "A9:C9", "val7");
+                AssertGroup(groups[6], "A10:C11", "val7");
+                AssertGroup(groups[7], "A12:C12", "val7");
+                AssertGroup(groups[8], "A13:C13", "val8");
+            }
         }
 
         [Fact]