add support for custom merge messages without 'TargetBranch' capture group

docs/configuration.md

@@ -193,9 +193,11 @@ merge-message-formats:
 
 The regular expression should contain the following capture groups:
 + SourceBranch - Identifies the source branch of the merge
-+ TargetBranch - Identifies the target of the merge
++ TargetBranch - Identifies the target of the merge (optional)
 + PullRequestNumber - Captures the pull-request number
 
+If regular expression doesn't contain TargetBranch then for matched messages current branch will be used.
+
 Custom merge message formats are evalauted _before_ any built in formats.
 
 ## Branch configuration

src/GitVersionCore.Tests/MergeMessageTests.cs

@@ -1,9 +1,9 @@
 using GitVersion;
+using GitVersion.Configuration;
 using NUnit.Framework;
 using Shouldly;
 using System;
 using System.Collections.Generic;
-using GitVersion.Configuration;
 
 namespace GitVersionCore.Tests
 {
@@ -149,7 +149,6 @@ public void ParsesBitBucketPullMergeMessage(
             sut.Version.ShouldBe(expectedVersion);
         }
 
-
         private static readonly object[] SmartGitMergeMessages =
         {
             new object[] { "Finish feature/one", "feature/one", null, null },
@@ -336,5 +335,41 @@ public void ReturnsAfterFirstMatchingPattern()
             sut.PullRequestNumber.ShouldBeNull();
             sut.Version.ShouldBeNull();
         }
+
+
+        private static readonly object[] BitBucketCloudCustomPullMergeMessages =
+        {
+            new object[] { "Merged in feature/one (pull request #1234)", "develop", "feature/one", "develop", null, 1234 },
+            new object[] { "Merged in hotfix/0.3.1 (pull request #1234)", "master", "hotfix/0.3.1", "master", new SemanticVersion(0,3,1), 1234 },
+            new object[] { "Merged in master (pull request #1234)", "develop", "master", "develop", null, 1234  }
+        };
+
+        [TestCaseSource(nameof(BitBucketCloudCustomPullMergeMessages))]
+        public void ParsesBitBucketCloudCustomPullMergeMessage(
+            string message,
+            string currentBranch,
+            string expectedMergedBranch,
+            string expectedTargetBranch,
+            SemanticVersion expectedVersion,
+            int? expectedPullRequestNumber)
+        {
+            var format = @"^Merged in (?<SourceBranch>[^']*) \(pull request #(?<PullRequestNumber>\d+)\)*";
+            var definition = "BitBucketCloud";
+            _config.MergeMessageFormats = new Dictionary<string, string>
+            {
+                [definition] = format
+            };
+
+            // Act
+            var sut = new MergeMessage(message, _config, currentBranch);
+
+            // Assert
+            sut.FormatName.ShouldBe("BitBucketCloud");
+            sut.TargetBranch.ShouldBe(expectedTargetBranch);
+            sut.MergedBranch.ShouldBe(expectedMergedBranch);
+            sut.IsMergedPullRequest.ShouldBeTrue();
+            sut.PullRequestNumber.ShouldBe(expectedPullRequestNumber);
+            sut.Version.ShouldBe(expectedVersion);
+        }
     }
 }

src/GitVersionCore/MergeMessage.cs

@@ -17,7 +17,7 @@ public class MergeMessage
             new MergeMessageFormat("RemoteTracking", @"^Merge remote-tracking branch '(?<SourceBranch>[^\s]*)'(?: into (?<TargetBranch>[^\s]*))*")
         };
 
-        public MergeMessage(string mergeMessage, Config config)
+        public MergeMessage(string mergeMessage, Config config, string currentBranch = default)
         {
             if (mergeMessage == null)
                 throw new NullReferenceException();
@@ -36,10 +36,15 @@ public MergeMessage(string mergeMessage, Config config)
                     FormatName = format.Name;
                     MergedBranch = match.Groups["SourceBranch"].Value;
 
-                    if (match.Groups["TargetBranch"].Success)
+                    var containsTargetBranchGroup = format.Pattern.GetGroupNames().Contains("TargetBranch");
+                    if (containsTargetBranchGroup && match.Groups["TargetBranch"].Success)
                     {
                         TargetBranch = match.Groups["TargetBranch"].Value;
                     }
+                    else
+                    {
+                        TargetBranch = currentBranch;
+                    }
 
                     if (int.TryParse(match.Groups["PullRequestNumber"].Value, out var pullNumber))
                     {

src/GitVersionCore/VersionCalculation/BaseVersionCalculators/MergeMessageBaseVersionStrategy.cs

@@ -51,7 +51,7 @@ static MergeMessage Inner(Commit mergeCommit, GitVersionContext context)
                 return null;
             }
 
-            var mergeMessage = new MergeMessage(mergeCommit.Message, context.FullConfiguration);
+            var mergeMessage = new MergeMessage(mergeCommit.Message, context.FullConfiguration, context.CurrentBranch.FriendlyName);
             return mergeMessage;
         }
 

src/GitVersionCore/VersionCalculation/MainlineVersionCalculator.cs

@@ -269,7 +269,7 @@ private static VersionField TryFindIncrementFromMergeMessage(Commit mergeCommit,
         {
             if (mergeCommit != null)
             {
-                var mergeMessage = new MergeMessage(mergeCommit.Message, context.FullConfiguration);
+                var mergeMessage = new MergeMessage(mergeCommit.Message, context.FullConfiguration, context.CurrentBranch.FriendlyName);
                 if (mergeMessage.MergedBranch != null)
                 {
                     var config = context.FullConfiguration.GetConfigForBranch(mergeMessage.MergedBranch);