Add helper DictionaryExtensions.SequenceEqual

tracer/src/Datadog.Trace/ExtensionMethods/DictionaryExtensions.cs

@@ -7,6 +7,7 @@
 using System.Collections;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using Datadog.Trace.Util;
 
 namespace Datadog.Trace.ExtensionMethods
@@ -128,5 +129,42 @@ public static TV Get<TK, TV>(this Dictionary<TK, TV> map, TK key, Func<TK, TV> c
             map[key] = newVal;
             return newVal;
         }
+
+        /// <summary>
+        /// Checks if two dictionaries contain the same keys and values.
+        /// Note that this method assumes the two dictionaries use the same
+        /// <see cref="IEqualityComparer"/>; using different comparers in each
+        /// dictionary is not supported.
+        /// </summary>
+        public static bool SequenceEqual(
+            this ReadOnlyDictionary<string, string> dict1,
+            ReadOnlyDictionary<string, string> dict2,
+            StringComparison valueComparison = StringComparison.Ordinal)
+        {
+            if (dict1 is null && dict2 is null)
+            {
+                return true;
+            }
+
+            if (dict1 is null || dict2 is null || dict1.Count != dict2.Count)
+            {
+                return false;
+            }
+
+            if (dict1.Count == 0 && dict2.Count == 0)
+            {
+                return true;
+            }
+
+            foreach (var kvp1 in dict1)
+            {
+                if (!dict2.TryGetValue(kvp1.Key, out var val2) || !string.Equals(kvp1.Value, val2, valueComparison))
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
     }
 }

tracer/test/Datadog.Trace.Tests/ExtensionMethods/DictionaryExtensionsTests.cs

@@ -0,0 +1,109 @@
+// <copyright file="DictionaryExtensionsTests.cs" company="Datadog">
+// Unless explicitly stated otherwise all files in this repository are licensed under the Apache 2 License.
+// This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2017 Datadog, Inc.
+// </copyright>
+
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using Datadog.Trace.ExtensionMethods;
+using Datadog.Trace.Util;
+using FluentAssertions;
+using Xunit;
+
+namespace Datadog.Trace.Tests.ExtensionMethods;
+
+public class DictionaryExtensionsTests
+{
+    [Fact]
+    public void SequenceEqual_HandlesBothNull()
+    {
+        ReadOnlyDictionary<string, string> dict1 = null;
+        dict1!.SequenceEqual(null).Should().BeTrue();
+    }
+
+    [Fact]
+    public void SequenceEqual_HandlesOneNull()
+    {
+        ReadOnlyDictionary<string, string> dict1 = null;
+        ReadOnlyDictionary<string, string> dict2 = ReadOnlyDictionary.Empty;
+        dict1!.SequenceEqual(dict2).Should().BeFalse();
+        dict2!.SequenceEqual(dict1).Should().BeFalse();
+    }
+
+    [Fact]
+    public void SequenceEqual_HandlesEmpty()
+    {
+        ReadOnlyDictionary<string, string> dict1 = ReadOnlyDictionary.Empty;
+        ReadOnlyDictionary<string, string> dict2 = ReadOnlyDictionary.Empty;
+        dict1.SequenceEqual(dict2).Should().BeTrue();
+        dict2.SequenceEqual(dict1).Should().BeTrue();
+    }
+
+    [Fact]
+    public void SequenceEqual_HandlesDifferentSizes()
+    {
+        ReadOnlyDictionary<string, string> dict1 = new(new Dictionary<string, string> { { "key", "value" } });
+        ReadOnlyDictionary<string, string> dict2 = ReadOnlyDictionary.Empty;
+        dict1.SequenceEqual(dict2).Should().BeFalse();
+        dict2.SequenceEqual(dict1).Should().BeFalse();
+    }
+
+    [Fact]
+    public void SequenceEqual_HandlesDifferentKeys()
+    {
+        ReadOnlyDictionary<string, string> dict1 = new(new Dictionary<string, string> { { "key1", "value" } });
+        ReadOnlyDictionary<string, string> dict2 = new(new Dictionary<string, string> { { "key2", "value" } });
+        dict1.SequenceEqual(dict2).Should().BeFalse();
+        dict2.SequenceEqual(dict1).Should().BeFalse();
+    }
+
+    [Theory]
+    [InlineData("value2")]
+    [InlineData("VALUE1")]
+    [InlineData("value1 ")]
+    [InlineData(" value1 ")]
+    [InlineData("")]
+    [InlineData(null)]
+    public void SequenceEqual_HandlesDifferentValues(string value)
+    {
+        ReadOnlyDictionary<string, string> dict1 = new(new Dictionary<string, string> { { "key", "value1" } });
+        ReadOnlyDictionary<string, string> dict2 = new(new Dictionary<string, string> { { "key", value } });
+        dict1.SequenceEqual(dict2).Should().BeFalse();
+        dict2.SequenceEqual(dict1).Should().BeFalse();
+    }
+
+    [Fact]
+    public void SequenceEqual_UsesDictionaryKeyComparer()
+    {
+        ReadOnlyDictionary<string, string> dict1 = new(new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase) { { "key", "value" } });
+        ReadOnlyDictionary<string, string> dict2 = new(new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase) { { "KEY", "value" } });
+        dict1.SequenceEqual(dict2).Should().BeTrue();
+        dict2.SequenceEqual(dict1).Should().BeTrue();
+    }
+
+    [Fact]
+    public void SequenceEqual_UsesDictionaryWithDifferentComparersIsNotSupported()
+    {
+        ReadOnlyDictionary<string, string> dict1 = new(new Dictionary<string, string>(StringComparer.Ordinal) { { "key", "value" } });
+        ReadOnlyDictionary<string, string> dict2 = new(new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase) { { "KEY", "value" } });
+
+        // reversing the order changes the result
+        dict1.SequenceEqual(dict2).Should().BeTrue();
+        dict2.SequenceEqual(dict1).Should().BeFalse();
+    }
+
+    [Theory]
+    [InlineData(StringComparison.Ordinal, "value", true)]
+    [InlineData(StringComparison.Ordinal, "VALUE", false)]
+    [InlineData(StringComparison.OrdinalIgnoreCase, "VALUE", true)]
+    public void SequenceEqual_UsesComparer(StringComparison comparison, string value, bool expected)
+    {
+        ReadOnlyDictionary<string, string> dict1 = new(new Dictionary<string, string> { { "key", "value" } });
+        ReadOnlyDictionary<string, string> dict2 = new(new Dictionary<string, string> { { "key", value } });
+
+        // reversing the order changes the result
+        dict1.SequenceEqual(dict2, comparison).Should().Be(expected);
+        dict2.SequenceEqual(dict1, comparison).Should().Be(expected);
+    }
+}