Implement Equals correctly for IdPartPair (#871)

Author: twsouthwick

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Added nullability attributes (#840, #849)
 - Added overload for `OpenXmlPartReader` and `OpenXmlReader.Create(...)` to ignore whitespace (#857)
 - Added `HexBinaryValue.TryGetBytes(...)` and `HexBinaryValue.Create(byte[])` to manage the encoding and decoding of bytes (#867)
+- Implemented `IEquatable<IdPartPair>` on `IdPartPair` to fix equality implementation there and obsoleted setters (#871)
 
 ## Version 2.12.1 - 2021-01-11
 

Directory.Build.props

@@ -7,7 +7,7 @@
 
     <!-- Because of the size of the project, to facilitate  quick development, by default only single
          frameworks will be build. This is customizable with the following possible values:
-         - net35:              .NET Framework 3.5 
+         - net35:              .NET Framework 3.5
          - net40:              .NET Framework 4.0
          - net46:              .NET Framework 4.6
          - netstandard1_3:     .NET Core 2.1 (but running .NET Standard 1.3 build)

src/DocumentFormat.OpenXml/Packaging/IdPartPair.cs

@@ -1,36 +1,37 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-#nullable disable
-
 using System;
 
+#if !NET5_0
+using DocumentFormat.OpenXml.Framework;
+#endif
+
 namespace DocumentFormat.OpenXml.Packaging
 {
     /// <summary>
     /// Represents a (RelationshipId, OpenXmlPart) pair.
     /// </summary>
-    public class IdPartPair
+    public class IdPartPair : IEquatable<IdPartPair>
     {
-        private string _id;
-        private OpenXmlPart _part;
-
         /// <summary>
         /// Gets or sets the relationship ID in the pair.
         /// </summary>
         public string RelationshipId
         {
-            get { return _id; }
-            set { _id = value; }
+            get;
+            [Obsolete("This object will be made immutable in a future release. Please use a new instance.")]
+            set;
         }
 
         /// <summary>
         /// Gets or sets the OpenXmlPart in the pair.
         /// </summary>
         public OpenXmlPart OpenXmlPart
         {
-            get { return _part; }
-            set { _part = value; }
+            get;
+            [Obsolete("This object will be made immutable in a future release. Please use a new instance.")]
+            set;
         }
 
         /// <summary>
@@ -40,24 +41,40 @@ public OpenXmlPart OpenXmlPart
         /// <param name="part">The OpenXmlPart.</param>
         public IdPartPair(string id, OpenXmlPart part)
         {
+#pragma warning disable CS0618 // Type or member is obsolete
             RelationshipId = id;
             OpenXmlPart = part;
+#pragma warning restore CS0618 // Type or member is obsolete
         }
 
-        /// <summary>
-        /// Determines whether this instance and another specified IdPartPair object have the same value.
-        /// </summary>
-        /// <param name="value">An IdPartPair.</param>
-        /// <returns>True if the value of the value parameter is the same as this instance; otherwise, false.</returns>
-        public bool Equals(IdPartPair value)
+        /// <inheritdoc/>
+        public override bool Equals(object? obj) => obj is IdPartPair other && Equals(other);
+
+        /// <inheritdoc/>
+        public override int GetHashCode()
+        {
+            var code = new HashCode();
+
+            code.Add(RelationshipId, StringComparer.Ordinal);
+
+            return code.ToHashCode();
+        }
+
+        /// <inheritdoc/>
+        public bool Equals(IdPartPair? value)
         {
             //Check for null
             if (value is null)
             {
                 return false;
             }
 
-            return string.Equals(_id, value._id, StringComparison.Ordinal) && (_part == value._part);
+            if (ReferenceEquals(this, value))
+            {
+                return true;
+            }
+
+            return string.Equals(RelationshipId, value.RelationshipId, StringComparison.Ordinal) && (OpenXmlPart == value.OpenXmlPart);
         }
     }
 }