Fix IndexOutOfRangeException in CreateFromGit when parsing malformed Git external links

src/MigrationTools.Clients.TfsObjectModel.Tests/Tools/TfsGitRepositoryInfoTests.cs

@@ -0,0 +1,117 @@
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+using Microsoft.TeamFoundation.SourceControl.WebApi;
+using Microsoft.TeamFoundation.WorkItemTracking.Client;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MigrationTools.Tools;
+
+namespace MigrationTools.Tests.Tools
+{
+    [TestClass()]
+    public class TfsGitRepositoryInfoTests
+    {
+        /// <summary>
+        /// Helper method to create a mock ExternalLink using reflection to avoid complex TFS object model setup
+        /// </summary>
+        private ExternalLink CreateMockExternalLink(string uri)
+        {
+            // Create a mock RegisteredLinkType using reflection
+            var linkTypeConstructor = typeof(RegisteredLinkType).GetConstructor(
+                BindingFlags.NonPublic | BindingFlags.Instance,
+                null,
+                new Type[] { typeof(string), typeof(string) },
+                null);
+
+            var linkType = (RegisteredLinkType)linkTypeConstructor.Invoke(new object[] { "MockLinkType", "Mock Link Type" });
+
+            // Create ExternalLink using the mock link type
+            return new ExternalLink(linkType, uri);
+        }
+
+        [TestMethod(), TestCategory("L0")]
+        public void CreateFromGit_ValidLinkWithThreeParts_ShouldSucceed()
+        {
+            // Arrange
+            var validLink = "vstfs:///Git/Commit/25f94570-e3e7-4b79-ad19-4b434787fd5a%2f50477259-3058-4dff-ba4c-e8c179ec5327%2f41dd2754058348d72a6417c0615c2543b9b55535";
+            var externalLink = CreateMockExternalLink(validLink);
+            var possibleRepos = new List<GitRepository>
+            {
+                new GitRepository { Id = Guid.Parse("50477259-3058-4dff-ba4c-e8c179ec5327") }
+            };
+
+            // Act
+            var result = TfsGitRepositoryInfo.CreateFromGit(externalLink, possibleRepos);
+
+            // Assert
+            Assert.IsNotNull(result);
+            Assert.AreEqual("50477259-3058-4dff-ba4c-e8c179ec5327", result.RepoID);
+            Assert.AreEqual("41dd2754058348d72a6417c0615c2543b9b55535", result.CommitID);
+        }
+
+        [TestMethod(), TestCategory("L0")]
+        public void CreateFromGit_ValidLinkWithMultipleCommitParts_ShouldSucceed()
+        {
+            // Arrange
+            var validLink = "vstfs:///Git/Commit/25f94570-e3e7-4b79-ad19-4b434787fd5a%2f50477259-3058-4dff-ba4c-e8c179ec5327%2f41dd2754058348d72a6417c0615c2543b9b55535%2fextra%2fparts";
+            var externalLink = CreateMockExternalLink(validLink);
+            var possibleRepos = new List<GitRepository>
+            {
+                new GitRepository { Id = Guid.Parse("50477259-3058-4dff-ba4c-e8c179ec5327") }
+            };
+
+            // Act
+            var result = TfsGitRepositoryInfo.CreateFromGit(externalLink, possibleRepos);
+
+            // Assert
+            Assert.IsNotNull(result);
+            Assert.AreEqual("50477259-3058-4dff-ba4c-e8c179ec5327", result.RepoID);
+            Assert.AreEqual("41dd2754058348d72a6417c0615c2543b9b55535%2fextra%2fparts", result.CommitID);
+        }
+
+        [TestMethod(), TestCategory("L0")]
+        public void CreateFromGit_InvalidLinkWithOnePart_ShouldReturnNull()
+        {
+            // Arrange
+            var invalidLink = "vstfs:///Git/Commit/25f94570-e3e7-4b79-ad19-4b434787fd5a";
+            var externalLink = CreateMockExternalLink(invalidLink);
+            var possibleRepos = new List<GitRepository>();
+
+            // Act
+            var result = TfsGitRepositoryInfo.CreateFromGit(externalLink, possibleRepos);
+
+            // Assert
+            Assert.IsNull(result);
+        }
+
+        [TestMethod(), TestCategory("L0")]
+        public void CreateFromGit_InvalidLinkWithTwoParts_ShouldReturnNull()
+        {
+            // Arrange
+            var invalidLink = "vstfs:///Git/Commit/25f94570-e3e7-4b79-ad19-4b434787fd5a%2f50477259-3058-4dff-ba4c-e8c179ec5327";
+            var externalLink = CreateMockExternalLink(invalidLink);
+            var possibleRepos = new List<GitRepository>();
+
+            // Act
+            var result = TfsGitRepositoryInfo.CreateFromGit(externalLink, possibleRepos);
+
+            // Assert
+            Assert.IsNull(result);
+        }
+
+        [TestMethod(), TestCategory("L0")]
+        public void CreateFromGit_EmptyLink_ShouldReturnNull()
+        {
+            // Arrange
+            var emptyLink = "vstfs:///Git/Commit/";
+            var externalLink = CreateMockExternalLink(emptyLink);
+            var possibleRepos = new List<GitRepository>();
+
+            // Act
+            var result = TfsGitRepositoryInfo.CreateFromGit(externalLink, possibleRepos);
+
+            // Assert
+            Assert.IsNull(result);
+        }
+    }
+}

src/MigrationTools.Clients.TfsObjectModel/Tools/TfsGitRepositoryInfo.cs

@@ -94,18 +94,20 @@ public static TfsGitRepositoryInfo CreateFromGit(ExternalLink gitExternalLink, I
             //vstfs:///Git/Commit/25f94570-e3e7-4b79-ad19-4b434787fd5a%2f50477259-3058-4dff-ba4c-e8c179ec5327%2f41dd2754058348d72a6417c0615c2543b9b55535
             string guidbits = gitExternalLink.LinkedArtifactUri.Substring(gitExternalLink.LinkedArtifactUri.LastIndexOf('/') + 1);
             string[] bits = Regex.Split(guidbits, "%2f", RegexOptions.IgnoreCase);
-            repoID = bits[1];
-            if (bits.Count() >= 3)
+
+            // Validate that we have at least 3 parts (projectId, repoId, commitId)
+            // This ensures bits[0], bits[1], and bits[2] are all accessible
+            if (bits.Length < 3)
             {
-                commitID = $"{bits[2]}";
-                for (int i = 3; i < bits.Count(); i++)
-                {
-                    commitID += $"%2f{bits[i]}";
-                }
+                Log.Warning("GitRepositoryInfo: Invalid Git external link format. Expected at least 3 parts separated by %2f, but got {count} parts. Link: {link}", bits.Length, gitExternalLink.LinkedArtifactUri);
+                return null;
             }
-            else
+
+            repoID = bits[1]; // Safe to access after length validation
+            commitID = $"{bits[2]}"; // Safe to access after length validation
+            for (int i = 3; i < bits.Count(); i++)
             {
-                commitID = bits[2];
+                commitID += $"%2f{bits[i]}";
             }
             gitRepo =
                 (from g in possibleRepos where string.Equals(g.Id.ToString(), repoID, StringComparison.OrdinalIgnoreCase) select g)