Fix for issue 2138

src/EPPlus/ExcelRangeBase.cs

@@ -2404,7 +2404,6 @@ private void DeleteThreadedComments(ExcelAddressBase Range)
         /// </summary>
         public void Dispose()
         {
-            //_worksheet = null;            
         }
 
         #endregion

src/EPPlus/ExcelWorksheet.cs

@@ -3617,7 +3617,11 @@ internal void SetValueInner(int row, int col, object value)
             var styleId = -1;
 
             styleId = GetStyleId(row, col);
-
+            if(_flags.GetFlagValue(row, col, CellFlags.RichText))
+            {
+                var rtc = _values.GetValue(row, col)._value as ExcelRichTextCollection;
+                rtc?.Dispose();
+            }   
             if (FullPrecision)
             {
                 _values.SetValue(row, col, value, styleId);

src/EPPlus/Style/RichText/ExcelRichTextCollection.cs

@@ -29,12 +29,13 @@ namespace OfficeOpenXml.Style
     /// <summary>
     /// Collection of Richtext objects
     /// </summary>
-    public class ExcelRichTextCollection : IEnumerable<ExcelRichText>
+    public class ExcelRichTextCollection : IEnumerable<ExcelRichText>, IDisposable
     {
         List<ExcelRichText> _list = new List<ExcelRichText>();
         internal ExcelRangeBase _cells = null;
         internal ExcelWorkbook _wb;
         internal bool _isComment=false;
+        private bool _isDisposed=false;
         internal ExcelRichTextCollection(ExcelWorkbook wb, ExcelRangeBase cells)
         {
             _wb = wb;
@@ -51,7 +52,6 @@ internal ExcelRichTextCollection(string s, ExcelRangeBase cells)
                 Add(s);
             }
         }
-
         internal ExcelRichTextCollection(ExcelRichTextCollection rtc, ExcelRangeBase cells)
         {
             _wb = cells._workbook;
@@ -115,10 +115,20 @@ public ExcelRichText this[int Index]
         {
             get
             {
+                CheckDeleted();
                 var item = _list[Index];
                 return item;
             }
         }
+
+        private void CheckDeleted()
+        {
+            if(_isDisposed)
+            {
+                throw (new ObjectDisposedException(@"This RichText object has been overwritten by another value and has been disposed. Please use the .RichText object to initiaze a new object, if you want to set the cell/object to a rich text value."));
+            }
+        }
+
         /// <summary>
         /// Items in the list
         /// </summary>
@@ -137,6 +147,7 @@ public int Count
         /// <returns></returns>
         public ExcelRichText Add(string Text, bool NewParagraph = false)
         {
+            CheckDeleted();
             if (NewParagraph) Text += "\n";
             return Insert(_list.Count, Text);
         }
@@ -149,6 +160,7 @@ public ExcelRichText Add(string Text, bool NewParagraph = false)
         /// <returns></returns>
         public ExcelRichText Insert(int index, string text)
         {
+            CheckDeleted();
             if (text == null) throw new ArgumentException("Text can't be null", "text");
             var rt = new ExcelRichText(text, this);
             rt.PreserveSpace = true;
@@ -195,7 +207,6 @@ public ExcelRichText Insert(int index, string text)
                 if (_isComment == false)
                 {
                     _cells._worksheet._flags.SetFlagValue(_cells._fromRow, _cells._fromCol, true, CellFlags.RichText);
-                    //_cells.SetIsRichTextFlag(true);
                 }
             }
             _list.Insert(index, rt);
@@ -207,19 +218,16 @@ public ExcelRichText Insert(int index, string text)
         /// </summary>
         public void Clear()
         {
+            CheckDeleted();
             _list.Clear();
-            if (_cells != null && _isComment == false)
-            {
-				_cells.DeleteMe(_cells, false, true, true, true, false, true, false, false, false);
-                _cells.SetIsRichTextFlag(false);
-            }
         }
         /// <summary>
         /// Removes an item at the specific index
         /// </summary>
         /// <param name="Index"></param>
         public void RemoveAt(int Index)
         {
+            CheckDeleted();
             _list.RemoveAt(Index);
             if (_cells != null && _list.Count == 0 && _isComment == false) _cells.SetIsRichTextFlag(false);
         }
@@ -229,6 +237,7 @@ public void RemoveAt(int Index)
         /// <param name="Item"></param>
         public void Remove(ExcelRichText Item)
         {
+            CheckDeleted();
             _list.Remove(Item);
             if (_cells != null && _list.Count == 0 && _isComment == false) _cells.SetIsRichTextFlag(false);
         }
@@ -248,6 +257,7 @@ public string Text
             }
             set
             {
+                CheckDeleted();
                 if (string.IsNullOrEmpty(value))
                 {
                     Clear();
@@ -312,6 +322,12 @@ System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
             return _list.GetEnumerator();
         }
 
+        public void Dispose()
+        {
+            _cells.Dispose();
+            _isDisposed = true;
+        }
+
         #endregion
     }
 }

src/EPPlusTest/Core/Range/RangeRichTextTests.cs

@@ -211,5 +211,53 @@ public void ValidateRichText_TextIsReflectedOnRemove()
             Assert.AreEqual(1, range.RichText.Count);
             Assert.AreEqual("1", range.Text);  // FAILS as "12"
         }
+        [TestMethod]
+        public void ValidateRichText_ClearShould()
+        {
+            var package = new ExcelPackage();
+            var ws = package.Workbook.Worksheets.Add("Test");
+            var rtc = ws.Cells[1, 1].RichText;
+            var rt1 = rtc.Add("A");
+            var rt2 = rtc.Add("B");
+
+            Assert.IsTrue(ws.Cells[1, 1].IsRichText);
+
+            Assert.AreEqual("AB", rtc.Text);
+            Assert.AreEqual("AB", ws.Cells[1, 1].Text);
+            Assert.AreEqual("AB", ws.Cells[1, 1].RichText.Text);
+
+            rtc.Clear();
+            Assert.AreEqual("", rtc.Text);
+            Assert.AreEqual("", ws.Cells[1, 1].Text);
+            Assert.AreEqual("", ws.Cells[1, 1].RichText.Text);
+            Assert.IsFalse(ws.Cells[1, 1].IsRichText);
+        }
+        [TestMethod]
+        public void ValidateRichText_ShouldThrowWhenCellHasBeenOverwritten()
+        {
+            var package = new ExcelPackage();
+            var ws = package.Workbook.Worksheets.Add("Test");
+            var rtc = ws.Cells[1, 1].RichText;
+            var rt1 = rtc.Add("A");
+            var rt2 = rtc.Add("B");
+
+            ws.Cells[1, 1].Value = "SomeValue";
+
+            Assert.ThrowsExactly<ObjectDisposedException>(() =>{
+                rtc.Add("c");
+            });
+
+            Assert.ThrowsExactly<ObjectDisposedException>(() => {
+                rtc.Insert(0, "d");
+            });
+
+            Assert.ThrowsExactly<ObjectDisposedException>(() => {
+                rtc.Clear();
+            });
+
+            Assert.ThrowsExactly<ObjectDisposedException>(() => {
+                rtc.Text = "ABCD";
+            });
+        }
     }
 }

src/EPPlusTest/Issues/LegacyTests/Issues.cs

@@ -4293,10 +4293,15 @@ public void s431()
                     .Select(p => p as ExcelPicture).ToList();
 
                 var pic = pics.First(p => p.Name == "Image_ExistingInventoryImg");
-                var image = File.ReadAllBytes("c:\\temp\\img1.png");
-                pic.Image.SetImage(image, ePictureType.Png);
-                image = File.ReadAllBytes("c:\\temp\\img2.png");
-                pics[1].Image.SetImage(image, ePictureType.Png);
+                var img1 = "c:\\temp\\img1.png";
+                if (File.Exists(img1))
+                {
+                    var image = File.ReadAllBytes("c:\\temp\\img1.png");
+                    pic.Image.SetImage(image, ePictureType.Png);
+
+                    image = File.ReadAllBytes("c:\\temp\\img2.png");
+                    pics[1].Image.SetImage(image, ePictureType.Png);
+                }
 
                 SaveAndCleanup(package);
             }