Find branch detached head is on

Author: distantcam

GitVersionCore/ExtensionMethods.cs

@@ -1,6 +1,7 @@
 namespace GitVersion
 {
     using System;
+    using System.Collections.Generic;
     using System.Text;
     using System.Text.RegularExpressions;
     using JetBrains.Annotations;
@@ -11,6 +12,7 @@ public static bool IsOdd(this int number)
         {
             return number % 2 != 0;
         }
+
         public static string TrimToFirstLine(this string s)
         {
             return s.Split(new[]
@@ -37,7 +39,6 @@ public static string TrimStart(this string value, string toTrim)
             return value.Substring(startIndex);
         }
 
-
         public static string JsonEncode(this string value)
         {
             if (value != null)
@@ -59,5 +60,25 @@ public static string RegexReplace(this string input, string pattern, string repl
             return Regex.Replace(input, pattern, replace, options);
         }
 
+        public static T OnlyOrDefault<T>(this IEnumerable<T> source)
+        {
+            if (source == null) throw new ArgumentNullException("source");
+
+            var list = source as IList<T>;
+
+            if (list != null && list.Count == 1)
+            {
+                return list[0];
+            }
+
+            using (var e = source.GetEnumerator())
+            {
+                if (!e.MoveNext()) return default(T);
+                var result = e.Current;
+                if (!e.MoveNext()) return result;
+            }
+
+            return default(T);
+        }
     }
 }

GitVersionCore/GitVersionContext.cs

@@ -1,5 +1,7 @@
 namespace GitVersion
 {
+    using System.Collections.Generic;
+    using System.Linq;
     using LibGit2Sharp;
 
     /// <summary>
@@ -15,16 +17,56 @@ public GitVersionContext(IRepository repository)
         public GitVersionContext(IRepository repository, Branch currentBranch)
         {
             Repository = repository;
-            CurrentBranch = currentBranch;
 
-            if (CurrentBranch != null)
+            if (currentBranch == null)
+                return;
+
+            CurrentCommit = currentBranch.Tip;
+
+            if (repository != null && currentBranch.IsDetachedHead())
             {
-                CurrentCommit = CurrentBranch.Tip;
+                CurrentBranch = GetBranchesContaininingCommit(CurrentCommit.Sha).OnlyOrDefault() ?? currentBranch;
+            }
+            else
+            {
+                CurrentBranch = currentBranch;
             }
         }
 
         public IRepository Repository { get; private set; }
         public Branch CurrentBranch { get; private set; }
         public Commit CurrentCommit { get; private set; }
+
+        private IEnumerable<Branch> GetBranchesContaininingCommit(string commitSha)
+        {
+            var directBranchHasBeenFound = false;
+            foreach (var branch in Repository.Branches)
+            {
+                if (branch.Tip.Sha != commitSha)
+                {
+                    continue;
+                }
+
+                directBranchHasBeenFound = true;
+                yield return branch;
+            }
+
+            if (directBranchHasBeenFound)
+            {
+                yield break;
+            }
+
+            foreach (var branch in Repository.Branches)
+            {
+                var commits = Repository.Commits.QueryBy(new CommitFilter { Since = branch }).Where(c => c.Sha == commitSha);
+
+                if (!commits.Any())
+                {
+                    continue;
+                }
+
+                yield return branch;
+            }
+        }
     }
 }

GitVersionCore/GitVersionFinder.cs

@@ -1,6 +1,5 @@
 namespace GitVersion
 {
-    using System;
     using System.Linq;
     using LibGit2Sharp;
 
@@ -34,7 +33,7 @@ void EnsureMainTopologyConstraints(GitVersionContext context)
 
         void EnsureHeadIsNotDetached(GitVersionContext context)
         {
-            if (!context.CurrentBranch.CanonicalName.Equals("(no branch)", StringComparison.OrdinalIgnoreCase))
+            if (!context.CurrentBranch.IsDetachedHead())
             {
                 return;
             }

GitVersionCore/LibGitExtensions.cs

@@ -7,7 +7,6 @@ namespace GitVersion
 
     static class LibGitExtensions
     {
-
         public static DateTimeOffset When(this Commit commit)
         {
             return commit.Committer.When;
@@ -69,5 +68,10 @@ public static IEnumerable<Commit> CommitsPriorToThan(this Branch branch, DateTim
         {
             return branch.Commits.SkipWhile(c => c.When() > olderThan);
         }
+
+        public static bool IsDetachedHead(this Branch branch)
+        {
+            return branch.CanonicalName.Equals("(no branch)", StringComparison.OrdinalIgnoreCase);
+        }
     }
-}
+}

Tests/UpdateAssemblyInfoTests.cs

@@ -66,7 +66,6 @@ public void StandardExecutionMode_CanDetermineTheVersionFromALocalDevelop()
         task.InnerExecute();
     }
 
-
     [Test]
     public void StandardExecutionMode_CanDetermineTheVersionFromALocalFeature()
     {
@@ -81,27 +80,6 @@ public void StandardExecutionMode_CanDetermineTheVersionFromALocalFeature()
         task.InnerExecute();
     }
 
-    [Test]
-    public void StandardExecutionMode_CannotDetermineTheVersionFromADetachedHead()
-    {
-        var repoPath = Clone(ASBMTestRepoWorkingDirPath);
-
-        using (var repo = new Repository(repoPath))
-        {
-            repo.Checkout("469f851");
-            Assert.IsTrue(repo.Info.IsHeadDetached);
-        }
-
-        var task = new UpdateAssemblyInfo
-        {
-            BuildEngine = new MockBuildEngine(),
-            SolutionDirectory = repoPath,
-        };
-
-        var exception = Assert.Throws<WarningException>(task.InnerExecute);
-        Assert.AreEqual("It looks like the branch being examined is a detached Head pointing to commit '469f851'. Without a proper branch name GitVersion cannot determine the build version.", exception.Message);
-    }
-
     [TestCase("Major")]
     [TestCase("MajorMinor")]
     [TestCase("MajorMinorPatch")]
@@ -138,7 +116,6 @@ public void StandardExecutionMode_ThrowsUponUnexpectedAssemblyVersioningSchemes(
 
         var exception = Assert.Throws<WarningException>(task.InnerExecute);
         Assert.AreEqual("Unexpected assembly versioning scheme 'Boom'.", exception.Message);
-
     }
 
     [SetUp]
@@ -148,12 +125,12 @@ public void SetUp()
         BuildServerList.Selector = arguments => new List<IBuildServer>();
     }
 
-
     [TearDown]
     public void TearDown()
     {
         BuildServerList.ResetSelector();
     }
+
     string CheckoutLocal(string repositoryPath, string monitoredReference)
     {
         var repoPath = Clone(repositoryPath);
@@ -164,5 +141,4 @@ string CheckoutLocal(string repositoryPath, string monitoredReference)
         }
         return repoPath;
     }
-
 }