Improved version calculation for feature branches in mainline mode - fixes #1154

In short when calculating the direct commits to master we need to remove any commits which are not on master. Otherwise we bump the mainline version on feature branches way too much. We also need to increment feature branches at the end of feature calculation unless the HEAD is a merge commit into the mainline branch (to cater for pull requests).

Author: JakeGinnivan

src/GitVersionCore.Tests/IntegrationTests/MainlineDevelopmentMode.cs

@@ -96,6 +96,7 @@ public void VerifyPullRequestsActLikeContinuousDelivery()
             fixture.AssertFullSemver(config, "1.0.1");
 
             fixture.BranchTo("feature/foo", "foo");
+            fixture.AssertFullSemver(config, "1.0.2-foo.0");
             fixture.MakeACommit();
             fixture.MakeACommit();
             fixture.Repository.CreatePullRequestRef("feature/foo", "master", normalise: true, prNumber: 8);
@@ -149,15 +150,20 @@ public void VerifyForwardMerge()
 
             fixture.BranchTo("feature/foo", "foo");
             fixture.MakeACommit();
+            fixture.AssertFullSemver(config, "1.0.2-foo.1");
             fixture.MakeACommit();
             fixture.AssertFullSemver(config, "1.0.2-foo.2");
 
             fixture.Checkout("master");
             fixture.MakeACommit();
             fixture.AssertFullSemver(config, "1.0.2");
             fixture.Checkout("feature/foo");
+            // This may seem surprising, but this happens because we branched off mainline
+            // and incremented. Mainline has then moved on. We do not follow mainline
+            // in feature branches, you need to merge mainline in to get the mainline version
+            fixture.AssertFullSemver(config, "1.0.2-foo.2");
             fixture.MergeNoFF("master");
-            fixture.AssertFullSemver(config, "1.0.4-foo.3");
+            fixture.AssertFullSemver(config, "1.0.3-foo.3");
         }
     }
 
@@ -240,6 +246,31 @@ public void VerifyMergingMasterToFeatureDoesNotStopMasterCommitsIncrementingVers
         }
     }
 
+    [Test]
+    public void VerifyIssue1154_CanForwardMergeMasterToFeatureBranch()
+    {
+        using (var fixture = new EmptyRepositoryFixture())
+        {
+            fixture.MakeACommit();
+            fixture.BranchTo("feature/branch2");
+            fixture.BranchTo("feature/branch1");
+            fixture.MakeACommit();
+            fixture.MakeACommit();
+
+            fixture.Checkout("master");
+            fixture.MergeNoFF("feature/branch1");
+            fixture.AssertFullSemver(config, "0.1.1");
+
+            fixture.Checkout("feature/branch2");
+            fixture.MakeACommit();
+            fixture.MakeACommit();
+            fixture.MakeACommit();
+            fixture.MergeNoFF("master");
+
+            fixture.AssertFullSemver(config, "0.1.2-branch2.4");
+        }
+    }
+
     [Test]
     public void VerifyMergingMasterIntoAFeatureBranchWorksWithMultipleBranches()
     {

src/GitVersionCore.Tests/IntegrationTests/RemoteRepositoryScenarios.cs

@@ -65,7 +65,6 @@ public void GivenARemoteGitRepositoryAheadOfLocalRepository_ThenChangesShouldPul
     [Test]
     public void GivenARemoteGitRepositoryWhenCheckingOutDetachedhead_UsingExistingImplementationThrowsException()
     {
-
         using (var fixture = new RemoteRepositoryFixture())
         {
             Commands.Checkout(

src/GitVersionCore/BranchConfigurationCalculator.cs

@@ -49,12 +49,12 @@ static IEnumerable<BranchConfig> LookupBranchConfiguration([NotNull] Config conf
         {
             if (config == null)
             {
-                throw new ArgumentNullException("config");
+                throw new ArgumentNullException(nameof(config));
             }
 
             if (currentBranch == null)
             {
-                throw new ArgumentNullException("currentBranch");
+                throw new ArgumentNullException(nameof(currentBranch));
             }
 
             return config.Branches.Where(b => Regex.IsMatch(currentBranch.FriendlyName, "^" + b.Value.Regex, RegexOptions.IgnoreCase)).Select(kvp => kvp.Value);

src/GitVersionCore/VersionCalculation/NextVersionCalculator.cs

@@ -95,13 +95,25 @@ SemanticVersion FindMainlineModeVersion(BaseVersion baseVersion, GitVersionConte
                 //         / |
                 // master *  *
                 // 
+
+                var mainlineTip = GetMainlineTip(context);
+                var commitsNotOnMainline = context.Repository.Commits.QueryBy(new CommitFilter
+                {
+                    IncludeReachableFrom = context.CurrentBranch,
+                    ExcludeReachableFrom = mainlineTip,
+                    SortBy = CommitSortStrategies.Reverse,
+                    FirstParentOnly = true
+                }).Where(c => c.Sha != baseVersion.BaseVersionSource.Sha && c.Parents.Count() == 1).ToList();
                 var commitLog = context.Repository.Commits.QueryBy(new CommitFilter
                 {
                     IncludeReachableFrom = context.CurrentBranch,
                     ExcludeReachableFrom = baseVersion.BaseVersionSource,
                     SortBy = CommitSortStrategies.Reverse,
                     FirstParentOnly = true
-                }).Where(c => c.Sha != baseVersion.BaseVersionSource.Sha).ToList();
+                })
+                .Where(c => c.Sha != baseVersion.BaseVersionSource.Sha)
+                .Except(commitsNotOnMainline)
+                .ToList();
 
                 var directCommits = new List<Commit>();
 
@@ -118,16 +130,16 @@ SemanticVersion FindMainlineModeVersion(BaseVersion baseVersion, GitVersionConte
                 if (context.CurrentBranch.FriendlyName != "master")
                 {
                     var mergedHead = context.CurrentCommit;
-                    var mainlineTip = GetMainlineTip(context);
                     var findMergeBase = context.Repository.ObjectDatabase.FindMergeBase(context.CurrentCommit, mainlineTip);
                     Logger.WriteInfo(string.Format("Current branch ({0}) was branch from {1}", context.CurrentBranch.FriendlyName, findMergeBase));
 
                     var branchIncrement = FindMessageIncrement(context, null, mergedHead, findMergeBase, directCommits);
                     // This will increment for any direct commits on master
                     mainlineVersion = IncrementForEachCommit(context, directCommits, mainlineVersion);
                     mainlineVersion.BuildMetaData = metaDataCalculator.Create(findMergeBase, context);
-                    // Only increment if head is not a merge commit, ensures PR's and forward merges end up correct.
-                    if (mergedHead.Parents.Count() == 1)
+                    // Don't increment if the merge commit is a merge into mainline
+                    // this ensures PR's and forward merges end up correct.
+                    if (mergedHead.Parents.Count() == 1 || mergedHead.Parents.First() != mainlineTip)
                     {
                         Logger.WriteInfo(string.Format("Performing {0} increment for current branch ", branchIncrement));
                         mainlineVersion = mainlineVersion.IncrementVersion(branchIncrement);