Fix #3606: Avoid allocations in ODataPath equality

src/Microsoft.OData.Core/UriParser/SemanticAst/ODataPath.cs

@@ -216,7 +216,16 @@ internal bool Equals(ODataPath other)
                 return false;
             }
 
-            return !this.segments.Where((t, i) => !t.Equals(other.segments[i])).Any();
+            int segmentsCount = this.segments.Count;
+            for (int index = 0; index < segmentsCount; index++)
+            {
+                if (!this.segments[index].Equals(other.segments[index]))
+                {
+                    return false;
+                }
+            }
+
+            return true;
         }
     }
 }

test/UnitTests/Microsoft.OData.Core.Tests/UriParser/SemanticAst/ODataPathTests.cs

@@ -67,6 +67,58 @@ public void PathsWithEqualivalentSegmentsAreEqual()
             Assert.True(new ODataPath(new DynamicPathSegment("foo")).Equals(new ODataPath(new DynamicPathSegment("foo"))));
         }
 
+        [Fact]
+        public void EmptyPathsAreEqual()
+        {
+            Assert.True(new ODataPath().Equals(new ODataPath()));
+        }
+
+        [Fact]
+        public void EqualsThrowsForNullPath()
+        {
+            ODataPath path = new ODataPath(MetadataSegment.Instance);
+
+            Assert.Throws<ArgumentNullException>("other", () => path.Equals((ODataPath)null));
+        }
+
+        [Fact]
+        public void PathsWithMultipleEquivalentSegmentsAreEqual()
+        {
+            ODataPath first = new ODataPath(
+                new DynamicPathSegment("first"),
+                new DynamicPathSegment("middle"),
+                new DynamicPathSegment("last"));
+            ODataPath second = new ODataPath(
+                new DynamicPathSegment("first"),
+                new DynamicPathSegment("middle"),
+                new DynamicPathSegment("last"));
+
+            Assert.True(first.Equals(second));
+        }
+
+        [Theory]
+        [InlineData(0)]
+        [InlineData(1)]
+        [InlineData(2)]
+        public void PathsWithMismatchAtAnyPositionAreNotEqual(int mismatchIndex)
+        {
+            ODataPathSegment[] firstSegments =
+            {
+                new DynamicPathSegment("first"),
+                new DynamicPathSegment("middle"),
+                new DynamicPathSegment("last")
+            };
+            ODataPathSegment[] secondSegments =
+            {
+                new DynamicPathSegment("first"),
+                new DynamicPathSegment("middle"),
+                new DynamicPathSegment("last")
+            };
+            secondSegments[mismatchIndex] = new DynamicPathSegment("different");
+
+            Assert.False(new ODataPath(firstSegments).Equals(new ODataPath(secondSegments)));
+        }
+
         [Fact]
         public void PathsShouldNotAllowSegmentsToBeNull()
         {