When a branch is merged in mainline, try to get the increment configuration for the merged branch

Author: JakeGinnivan

src/GitVersionCore.Tests/IntegrationTests/MainlineDevelopmentMode.cs

@@ -6,6 +6,7 @@
 using GitVersionCore.Tests;
 using LibGit2Sharp;
 using NUnit.Framework;
+using System.Collections.Generic;
 
 public class MainlineDevelopmentMode
 {
@@ -206,7 +207,7 @@ public void VerifyMergingMasterToFeatureDoesNotCauseBranchCommitsToIncrementVers
 
             fixture.BranchTo("feature/foo", "foo");
             fixture.MakeACommit("first in foo");
-            
+
             fixture.Checkout("master");
             fixture.MakeACommit("second in master");
 
@@ -303,6 +304,41 @@ public void VerifyMergingMasterIntoAFeatureBranchWorksWithMultipleBranches()
             fixture.AssertFullSemver(config, "1.0.2");
         }
     }
+
+    [Test]
+    public void MergingFeatureBranchThatIncrementsMinorNumberIncrementsMinorVersionOfMaster()
+    {
+        var currentConfig = new Config
+        {
+            VersioningMode = VersioningMode.Mainline,
+            Branches = new Dictionary<string, BranchConfig>
+             {
+                 {
+                    "feature", new BranchConfig
+                     {
+                         VersioningMode = VersioningMode.ContinuousDeployment,
+                         Increment = IncrementStrategy.Minor
+                     }
+                 }
+             }
+        };
+
+        using (var fixture = new EmptyRepositoryFixture())
+        {
+            fixture.MakeACommit("first in master");
+            fixture.MakeATaggedCommit("1.0.0");
+            fixture.AssertFullSemver(currentConfig, "1.0.0");
+
+            fixture.BranchTo("feature/foo", "foo");
+            fixture.MakeACommit("first in foo");
+            fixture.MakeACommit("second in foo");
+            fixture.AssertFullSemver(currentConfig, "1.1.0-foo.2");
+
+            fixture.Checkout("master");
+            fixture.MergeNoFF("feature/foo");
+            fixture.AssertFullSemver(currentConfig, "1.1.0");
+        }
+    }
 }
 
 static class CommitExtensions

src/GitVersionCore/VersionCalculation/MainlineVersionCalculator.cs

@@ -192,12 +192,23 @@ private static VersionField FindMessageIncrement(
                 new[] { mergeCommit }.Union(context.Repository.Commits.QueryBy(filter)).ToList();
             commitLog.RemoveAll(c => commits.Any(c1 => c1.Sha == c.Sha));
             return IncrementStrategyFinder.GetIncrementForCommits(context, commits)
-                ?? TryFindIncrementFromMergeMessage(mergeCommit);
+                ?? TryFindIncrementFromMergeMessage(mergeCommit, context);
         }
 
-        private static VersionField TryFindIncrementFromMergeMessage(Commit mergeCommit)
+        private static VersionField TryFindIncrementFromMergeMessage(Commit mergeCommit, GitVersionContext context)
         {
-
+            if (mergeCommit != null)
+            {
+                var mergeMessage = new MergeMessage(mergeCommit.Message, context.FullConfiguration);
+                if (mergeMessage.MergedBranch != null)
+                {
+                    var config = context.FullConfiguration.GetConfigForBranch(mergeMessage.MergedBranch);
+                    if (config != null && config.Increment.HasValue && config.Increment != IncrementStrategy.Inherit)
+                    {
+                        return config.Increment.Value.ToVersionField();
+                    }
+                }
+            }
 
             // Fallback to patch
             return VersionField.Patch;