Improve ExecuteCore.ExecuteInternal when HEAD is not pointing at the desired branch

src/GitVersionCore.Tests/GitToolsTestingExtensions.cs

@@ -15,14 +15,14 @@ public static Config ApplyDefaults(this Config config)
             return config;
         }
 
-        public static VersionVariables GetVersion(this RepositoryFixtureBase fixture, Config configuration = null, IRepository repository = null, string commitId = null, bool isForTrackedBranchOnly = true)
+        public static VersionVariables GetVersion(this RepositoryFixtureBase fixture, Config configuration = null, IRepository repository = null, string commitId = null, bool isForTrackedBranchOnly = true, string targetBranch = null)
         {
             if (configuration == null)
             {
                 configuration = new Config();
                 ConfigurationProvider.ApplyDefaultsTo(configuration);
             }
-            var gitVersionContext = new GitVersionContext(repository ?? fixture.Repository, configuration, isForTrackedBranchOnly, commitId);
+            var gitVersionContext = new GitVersionContext(repository ?? fixture.Repository, targetBranch, configuration, isForTrackedBranchOnly, commitId);
             var executeGitVersion = ExecuteGitVersion(gitVersionContext);
             var variables = VariableProvider.GetVariablesFor(executeGitVersion, gitVersionContext.Configuration, gitVersionContext.IsCurrentCommitTagged);
             try
@@ -37,19 +37,19 @@ public static VersionVariables GetVersion(this RepositoryFixtureBase fixture, Co
             }
         }
 
-        public static void AssertFullSemver(this RepositoryFixtureBase fixture, string fullSemver, IRepository repository = null, string commitId = null, bool isForTrackedBranchOnly = true)
+        public static void AssertFullSemver(this RepositoryFixtureBase fixture, string fullSemver, IRepository repository = null, string commitId = null, bool isForTrackedBranchOnly = true, string targetBranch = null)
         {
-            fixture.AssertFullSemver(new Config(), fullSemver, repository, commitId, isForTrackedBranchOnly);
+            fixture.AssertFullSemver(new Config(), fullSemver, repository, commitId, isForTrackedBranchOnly, targetBranch);
         }
 
-        public static void AssertFullSemver(this RepositoryFixtureBase fixture, Config configuration, string fullSemver, IRepository repository = null, string commitId = null, bool isForTrackedBranchOnly = true)
+        public static void AssertFullSemver(this RepositoryFixtureBase fixture, Config configuration, string fullSemver, IRepository repository = null, string commitId = null, bool isForTrackedBranchOnly = true, string targetBranch = null)
         {
             ConfigurationProvider.ApplyDefaultsTo(configuration);
             Console.WriteLine("---------");
 
             try
             {
-                var variables = fixture.GetVersion(configuration, repository, commitId, isForTrackedBranchOnly);
+                var variables = fixture.GetVersion(configuration, repository, commitId, isForTrackedBranchOnly, targetBranch);
                 variables.FullSemVer.ShouldBe(fullSemver);
             }
             catch (Exception)

src/GitVersionCore.Tests/GitVersionContextBuilder.cs

@@ -61,7 +61,8 @@ public GitVersionContext Build()
         {
             var configuration = config ?? new Config();
             ConfigurationProvider.ApplyDefaultsTo(configuration);
-            return new GitVersionContext(repository ?? CreateRepository(), configuration);
+            var repo = repository ?? CreateRepository();
+            return new GitVersionContext(repo, repo.Head, configuration);
         }
 
         IRepository CreateRepository()

src/GitVersionCore.Tests/GitVersionContextTests.cs

@@ -144,7 +144,7 @@ public void CanFindParentBranchForInheritingIncrementStrategy()
                 Commands.Checkout(repo.Repository, featureBranch);
                 repo.Repository.MakeACommit();
 
-                var context = new GitVersionContext(repo.Repository, config);
+                var context = new GitVersionContext(repo.Repository, repo.Repository.Head, config);
                 context.Configuration.Increment.ShouldBe(IncrementStrategy.Major);
             }
         }

src/GitVersionCore.Tests/IntegrationTests/BranchWithoutCommitScenario.cs

@@ -0,0 +1,22 @@
+using GitTools.Testing;
+using GitVersionCore.Tests;
+using LibGit2Sharp;
+using NUnit.Framework;
+
+[TestFixture]
+public class BranchWithoutCommitScenario
+{
+    [Test]
+    public void CanTakeVersionFromReleaseBranch()
+    {
+        using (var fixture = new EmptyRepositoryFixture())
+        {
+            fixture.Repository.MakeATaggedCommit("1.0.3");
+            var commit = fixture.Repository.MakeACommit();
+            fixture.Repository.CreateBranch("release-4.0.123");
+            fixture.Checkout(commit.Sha);
+
+            fixture.AssertFullSemver("4.0.123-beta.1+0", fixture.Repository, commit.Sha, false, "release-4.0.123");
+        }
+    }
+}

src/GitVersionCore/ExecuteCore.cs

@@ -108,7 +108,7 @@ VersionVariables ExecuteInternal(string targetBranch, string commitId, GitPrepar
 
             return gitPreparer.WithRepository(repo =>
             {
-                var gitVersionContext = new GitVersionContext(repo, configuration, commitId: commitId);
+                var gitVersionContext = new GitVersionContext(repo, targetBranch, configuration, commitId: commitId);
                 var semanticVersion = versionFinder.FindVersion(gitVersionContext);
 
                 return VariableProvider.GetVariablesFor(semanticVersion, gitVersionContext.Configuration, gitVersionContext.IsCurrentCommitTagged);

src/GitVersionCore/GitVersionContext.cs

@@ -9,8 +9,8 @@
     /// </summary>
     public class GitVersionContext
     {
-        public GitVersionContext(IRepository repository, Config configuration, bool isForTrackingBranchOnly = true, string commitId = null)
-            : this(repository, repository.Head, configuration, isForTrackingBranchOnly, commitId)
+        public GitVersionContext(IRepository repository, string targetBranch, Config configuration, bool onlyEvaluateTrackedBranches = true, string commitId = null)
+             : this(repository, GitVersionContext.GetTargetBranch(repository, targetBranch), configuration, onlyEvaluateTrackedBranches, commitId)
         {
         }
 
@@ -146,5 +146,31 @@ void CalculateEffectiveConfiguration()
                 currentBranchConfig.TracksReleaseBranches.Value,
                 currentBranchConfig.IsReleaseBranch.Value);
         }
+
+        private static Branch GetTargetBranch(IRepository repository, string targetBranch)
+        {
+            // By default, we assume HEAD is pointing to the desired branch
+            var desiredBranch = repository.Head;
+
+            // Make sure the desired branch has been specified
+            if (!string.IsNullOrEmpty(targetBranch))
+            {
+                // There are some edge cases where HEAD is not pointing to the desired branch.
+                // Therefore it's important to verify if 'currentBranch' is indeed the desired branch.
+                if (desiredBranch.CanonicalName != targetBranch)
+                {
+                    // In the case where HEAD is not the desired branch, try to find the branch with matching name
+                    desiredBranch = repository?.Branches?
+                        .SingleOrDefault(b =>
+                            b.CanonicalName == targetBranch ||
+                            b.FriendlyName == targetBranch);
+
+                    // Failsafe in case the specified branch is invalid
+                    desiredBranch = desiredBranch ?? repository.Head;
+                }
+            }
+
+            return desiredBranch;
+        }
     }
 }