port xmlunit/#235 to XMLUnit.NET

Author: bodewig

RELEASE_NOTES.md

@@ -2,6 +2,12 @@
 
 ## XMLUnit.NET 2.9.1 - /not released, yet/
 
+* added a new `FullDescription` method to `Diff` that provides a
+  string-representation of all differences - not just the first one
+  like `ToString` does.
+  Based on Java PR [xmlunit/#235](https://github.com/xmlunit/xmlunit/issues/235) by
+  [@Boiarshinov](https://github.com/Boiarshinov)
+
 ## XMLUnit.NET 2.9.0 - /Released 2020-10-30/
 
 * `ISource` now extends `IDisposable` to allow releasing unmanaged

src/main/net-core/Diff/Diff.cs

@@ -14,6 +14,7 @@ limitations under the License.
 
 using System.Collections.Generic;
 using System.Linq;
+using System.Text;
 
 namespace Org.XmlUnit.Diff {
 
@@ -106,5 +107,35 @@ public string ToString(IComparisonFormatter formatter) {
             }
             return differences.First().Comparison.ToString(formatter);
         }
+
+        /// <summary>
+        /// Returns a string representation of this diff using
+        /// internal IComparisonFormatter or DefaultComparisonFormatter
+        /// if formatter wasn't set.
+        /// </summary>
+        /// <remarks>
+        /// Each comparison result separated by the end of the line.
+        /// </remarks>
+        /// <returns>a string representation of this diff</returns>
+        public string FullDescription() {
+            return FullDescription(formatter);
+        }
+
+        /// <summary>
+        /// Returns a string representation of this diff using the
+        /// given IComparisonFormatter}
+        /// </summary>
+        /// <param name="formatter">the formatter to use</param>
+        /// <returns>a string representation of this diff</returns>
+        public string FullDescription(IComparisonFormatter formatter) {
+            if (!HasDifferences()) {
+                return "[identical]";
+            }
+            StringBuilder result = new StringBuilder();
+            foreach (Difference d in Differences) {
+                result.AppendLine(d.Comparison.ToString(formatter));
+            }
+            return result.ToString().TrimEnd();
+        }
     }
 }