Use Ordinal string comparison for TargetAlias (#7224)

Author: SimonCropp

src/NuGet.Core/NuGet.ProjectModel/LockFile/LockFile.cs

@@ -41,7 +41,7 @@ public LockFileTarget GetTarget(NuGetFramework framework, string runtimeIdentifi
         public LockFileTarget GetTarget(string frameworkAlias, string runtimeIdentifier)
         {
             return Targets.FirstOrDefault(t =>
-                t.TargetAlias.Equals(frameworkAlias) &&
+                string.Equals(t.TargetAlias, frameworkAlias, StringComparison.Ordinal) &&
                 (string.IsNullOrEmpty(runtimeIdentifier) && string.IsNullOrEmpty(t.RuntimeIdentifier) ||
                  string.Equals(runtimeIdentifier, t.RuntimeIdentifier, StringComparison.OrdinalIgnoreCase)));
         }

test/NuGet.Core.Tests/NuGet.ProjectModel.Test/LockFileTests.cs

@@ -920,6 +920,28 @@ public void LockFile_GetTarget_WithAliasAndSameFramework_ReturnsCorrectLockFileT
             targetWithRid.TargetAlias.Should().Be("net5.0");
         }
 
+        [Fact]
+        public void LockFile_GetTarget_WithAlias_WhenTargetAliasIsNull_ReturnsNull()
+        {
+            // Arrange
+            LockFile lockFile = new LockFile()
+            {
+                Targets = new List<LockFileTarget>()
+                {
+                    new() {
+                        TargetFramework = FrameworkConstants.CommonFrameworks.Net50,
+                        TargetAlias = null
+                    },
+                }
+            };
+
+            // Act
+            LockFileTarget target = lockFile.GetTarget("net5.0", runtimeIdentifier: null);
+
+            // Assert
+            target.Should().BeNull();
+        }
+
         private LockFile Parse(string lockFileContent, string path)
         {
             var reader = new LockFileFormat();