Ability to merge release back to develop

This preserves the correct version when merging a release back into develop.
This also changes the semantics of the 0+1 part of the semantic version so that it represents the number of changes since the previous tagged release (e.g. version 1.0.0-beta.1+5 gets reset to 1.0.0-beta.2+0)

Author: dtabuenc

GitVersionCore.Tests/GitFlow/UncycloScenarios.cs

@@ -76,7 +76,7 @@ public void MinorReleaseExample()
 
             // Make a commit after a tag should bump up the beta
             fixture.Repository.MakeACommit();
-            fixture.AssertFullSemver("1.3.0-beta.2+2");
+            fixture.AssertFullSemver("1.3.0-beta.2+0");
 
             // Merge release branch to master
             fixture.Repository.Checkout("master");

GitVersionCore.Tests/GitHubFlow/ReleaseBranchTests.cs

@@ -57,4 +57,40 @@ public void WhenReleaseBranchIsMergedIntoMasterHighestVersionIsTakenWithIt()
             fixture.AssertFullSemver("2.0.0+11");
         }
     }
+
+    [Test]
+    public void WhenMergingReleaseBackToDevShouldNotResetBetaVersion()
+    {
+        using (var fixture = new EmptyRepositoryFixture())
+        {
+            const string TaggedVersion = "1.0.3";
+            fixture.Repository.MakeATaggedCommit(TaggedVersion);
+            fixture.Repository.CreateBranch("develop");
+            fixture.Repository.Checkout("develop");
+
+            fixture.Repository.MakeCommits(1);
+
+            fixture.Repository.CreateBranch("release-2.0.0");
+            fixture.Repository.Checkout("release-2.0.0");
+            fixture.Repository.MakeCommits(1);
+
+            fixture.AssertFullSemver("2.0.0-beta.1+1");
+
+            //tag it to bump to beta 2
+            fixture.Repository.ApplyTag("2.0.0-beta1");
+
+            fixture.Repository.MakeCommits(1);
+
+            fixture.AssertFullSemver("2.0.0-beta.2+0");
+
+            //merge down to develop
+            fixture.Repository.Checkout("develop");
+            fixture.Repository.MergeNoFF("release-2.0.0", Constants.SignatureNow());
+
+            //but keep working on the release
+            fixture.Repository.Checkout("release-2.0.0");
+
+            fixture.AssertFullSemver("2.0.0-beta.2+0");
+        }
+    }
 }

GitVersionCore/GitFlow/BranchFinders/ReleaseVersionFinder.cs

@@ -1,5 +1,6 @@
 namespace GitVersion
 {
+    using System.Collections.Generic;
     using System.Linq;
     using LibGit2Sharp;
 
@@ -11,26 +12,73 @@ public SemanticVersion FindVersion(GitVersionContext context)
             var shortVersion = ShortVersionParser.Parse(versionString);
 
             EnsureVersionIsValid(shortVersion, context.CurrentBranch);
-            var semanticVersionPreReleaseTag = "beta.1";
-
-            var nbHotfixCommits = BranchCommitDifferenceFinder.NumberOfCommitsInBranchNotKnownFromBaseBranch(context.Repository, context.CurrentBranch, BranchType.Release, "develop");
+            SemanticVersionPreReleaseTag semanticVersionPreReleaseTag = "beta.1";
 
-            var tagVersion = RecentTagVersionExtractor.RetrieveMostRecentOptionalTagVersion(context.Repository, shortVersion, context.CurrentBranch.Commits.Take(nbHotfixCommits + 1));
+            var tagsApplicableToBranchVersion = context.Repository.SemVerTagsRelatedToVersion(shortVersion).OrderByDescending(tag => SemanticVersion.Parse(tag.Name)).ToList();
+            var latestTaggedCommit = tagsApplicableToBranchVersion.Select(tag => tag.Target).FirstOrDefault();
+
+            var numberOfCommitsSinceLastTagOrBranchPoint = NumberOfCommitsSinceLastTagOrBranchPoint(context, tagsApplicableToBranchVersion, "develop");
+
+            var tagVersion = RetrieveMostRecentOptionalTagVersion(tagsApplicableToBranchVersion);
+
             if (tagVersion != null)
             {
-                semanticVersionPreReleaseTag = tagVersion;
+                semanticVersionPreReleaseTag = tagVersion.PreReleaseTag;
+                if (latestTaggedCommit != context.CurrentCommit)
+                {
+                    semanticVersionPreReleaseTag.Number++;
+                }
             }
+
             return new SemanticVersion
             {
                 Major = shortVersion.Major,
                 Minor = shortVersion.Minor,
                 Patch = shortVersion.Patch,
                 PreReleaseTag = semanticVersionPreReleaseTag,
-                BuildMetaData = new SemanticVersionBuildMetaData(nbHotfixCommits, context.CurrentBranch.Name, context.CurrentCommit.Sha, context.CurrentCommit.When())
+                BuildMetaData = new SemanticVersionBuildMetaData(numberOfCommitsSinceLastTagOrBranchPoint, context.CurrentBranch.Name, context.CurrentCommit.Sha, context.CurrentCommit.When())
             };
         }
 
-        void EnsureVersionIsValid(ShortVersion version, Branch branch)
+        static SemanticVersion RetrieveMostRecentOptionalTagVersion(List<Tag> tagsInDescendingOrder)
+        {
+            return tagsInDescendingOrder.Select(tag => SemanticVersion.Parse(tag.Name)).FirstOrDefault();
+        }
+
+        static int NumberOfCommitsSinceLastTagOrBranchPoint(GitVersionContext context, List<Tag> tagsInDescendingOrder,  string baseBranchName)
+        {
+            if (!tagsInDescendingOrder.Any())
+            {
+                return BranchCommitDifferenceFinder.NumberOfCommitsInBranchNotKnownFromBaseBranch(context.Repository, context.CurrentBranch, BranchType.Release, baseBranchName);
+            }
+
+            var mostRecentTag = tagsInDescendingOrder.First();
+            var ancestor = mostRecentTag;
+            if (mostRecentTag.Target == context.CurrentCommit)
+            {
+                var previousTag = tagsInDescendingOrder.Skip(1).FirstOrDefault();
+                if (previousTag != null)
+                {
+                    ancestor = previousTag;
+                }
+                else
+                {
+                    return BranchCommitDifferenceFinder.NumberOfCommitsInBranchNotKnownFromBaseBranch(context.Repository, context.CurrentBranch, BranchType.Release, baseBranchName);
+                }
+
+            }
+
+            var filter = new CommitFilter
+            {
+                Since = context.CurrentCommit,
+                Until = ancestor.Target,
+                SortBy = CommitSortStrategies.Topological | CommitSortStrategies.Time
+            };
+
+            return context.Repository.Commits.QueryBy(filter).Count() - 1;
+        }
+
+        static void EnsureVersionIsValid(ShortVersion version, Branch branch)
         {
             if (version.Patch != 0)
             {

GitVersionCore/LibGitExtensions.cs

@@ -39,6 +39,23 @@ public static IEnumerable<Tag> TagsByDate(this IRepository repository, Commit co
                 });
         }
 
+        public static IEnumerable<Tag> SemVerTagsRelatedToVersion(this IRepository repository, ShortVersion version)
+        {
+            foreach (var tag in repository.Tags)
+            {
+                SemanticVersion tagVersion;
+                if (SemanticVersion.TryParse(tag.Name, out tagVersion))
+                {
+                    if (version.Major == tagVersion.Major &&
+                        version.Minor == tagVersion.Minor &&
+                        version.Patch == tagVersion.Patch)
+                    {
+                        yield return tag;
+                    }
+                }
+            }
+        }
+
         public static GitObject PeeledTarget(this Tag tag)
         {
             var target = tag.Target;