Make commit message configurable

scm-core/src/main/java/sonia/scm/repository/api/MergeCommandBuilder.java

@@ -10,8 +10,8 @@ import sonia.scm.repository.spi.MergeCommandRequest;
  * the branches could be merged without conflicts ({@link #dryRun()}). To do so, you have to specify the name of
  * the target branch ({@link #setTargetBranch(String)}) and the name of the branch that should be merged
  * ({@link #setBranchToMerge(String)}). Additionally you can specify an author that should be used for the commit
- * ({@link #setAuthor(Person)}) if you are not doing a dry run only. If no author is specified, the logged in user
- * will be used instead.
+ * ({@link #setAuthor(Person)}) and a message template ({@link #setMessageTemplate(String)}) if you are not doing a dry
+ * run only. If no author is specified, the logged in user and a default message will be used instead.
  *
  * To actually merge <code>feature_branch</code> into <code>integration_branch</code> do this:
  * <pre><code>
@@ -91,6 +91,25 @@ public class MergeCommandBuilder {
     return this;
   }
 
+  /**
+   * Use this to set a template for the commit message. If no message is set, a default message will be used.
+   *
+   * You can use the placeholder <code>{0}</code> for the branch to be merged and <code>{1}</code> for the target
+   * branch, eg.:
+   *
+   * <pre><code>
+   * ...setMessageTemplate("Merge of {0} into {1}")...
+   * </code></pre>
+   *
+   * This is optional and for {@link #executeMerge()} only.
+   *
+   * @return This builder instance.
+   */
+  public MergeCommandBuilder setMessageTemplate(String messageTemplate) {
+    request.setMessageTemplate(messageTemplate);
+    return this;
+  }
+
   /**
    * Use this to reset the command.
    * @return This builder instance.

scm-core/src/main/java/sonia/scm/repository/spi/MergeCommandRequest.java

@@ -16,6 +16,7 @@ public class MergeCommandRequest implements Validateable, Resetable, Serializabl
   private String branchToMerge;
   private String targetBranch;
   private Person author;
+  private String messageTemplate;
 
   public String getBranchToMerge() {
     return branchToMerge;
@@ -41,6 +42,14 @@ public class MergeCommandRequest implements Validateable, Resetable, Serializabl
     this.author = author;
   }
 
+  public String getMessageTemplate() {
+    return messageTemplate;
+  }
+
+  public void setMessageTemplate(String messageTemplate) {
+    this.messageTemplate = messageTemplate;
+  }
+
   public boolean isValid() {
     return !Strings.isNullOrEmpty(getBranchToMerge())
       && !Strings.isNullOrEmpty(getTargetBranch());

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitMergeCommand.java

@@ -1,5 +1,6 @@
 package sonia.scm.repository.spi;
 
+import com.google.common.base.Strings;
 import org.apache.shiro.SecurityUtils;
 import org.apache.shiro.subject.Subject;
 import org.eclipse.jgit.api.Git;
@@ -19,15 +20,16 @@ import sonia.scm.repository.api.MergeDryRunCommandResult;
 import sonia.scm.user.User;
 
 import java.io.IOException;
+import java.text.MessageFormat;
 
 public class GitMergeCommand extends AbstractGitCommand implements MergeCommand {
 
   private static final Logger logger = LoggerFactory.getLogger(GitMergeCommand.class);
 
-  private static final String MERGE_COMMIT_MESSAGE_TEMPLATE =
-    "Merge of branch %s into %s\n" +
-    "\n" +
-    "Automatic merge by SCM-Manager.";
+  private static final String MERGE_COMMIT_MESSAGE_TEMPLATE = String.join("\n",
+    "Merge of branch {0} into {1}",
+    "",
+    "Automatic merge by SCM-Manager.");
 
   private final GitWorkdirFactory workdirFactory;
 
@@ -64,11 +66,13 @@ public class GitMergeCommand extends AbstractGitCommand implements MergeCommand
     private final String toMerge;
     private final Person author;
     private final Git clone;
+    private final String messageTemplate;
 
     private MergeWorker(Repository clone, MergeCommandRequest request) {
       this.target = request.getTargetBranch();
       this.toMerge = request.getBranchToMerge();
       this.author = request.getAuthor();
+      this.messageTemplate = request.getMessageTemplate();
       this.clone = new Git(clone);
     }
 
@@ -111,13 +115,21 @@ public class GitMergeCommand extends AbstractGitCommand implements MergeCommand
       try {
         clone.commit()
           .setAuthor(authorToUse.getName(), authorToUse.getMail())
-          .setMessage(String.format(MERGE_COMMIT_MESSAGE_TEMPLATE, toMerge, target))
+          .setMessage(MessageFormat.format(determineMessageTemplate(), toMerge, target))
           .call();
       } catch (GitAPIException e) {
         throw new InternalRepositoryException("could not commit merge between branch " + toMerge + " and " + target, e);
       }
     }
 
+    private String determineMessageTemplate() {
+      if (Strings.isNullOrEmpty(messageTemplate)) {
+        return MERGE_COMMIT_MESSAGE_TEMPLATE;
+      } else {
+        return messageTemplate;
+      }
+    }
+
     private Person determineAuthor() {
       if (author == null) {
         Subject subject = SecurityUtils.getSubject();

scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitMergeCommandTest.java

@@ -67,14 +67,36 @@ public class GitMergeCommandTest extends AbstractGitCommandTestBase {
     Iterable<RevCommit> commits = new Git(repository).log().add(repository.resolve("master")).setMaxCount(1).call();
     RevCommit mergeCommit = commits.iterator().next();
     PersonIdent mergeAuthor = mergeCommit.getAuthorIdent();
+    String message = mergeCommit.getFullMessage();
     assertThat(mergeAuthor.getName()).isEqualTo("Dirk Gently");
     assertThat(mergeAuthor.getEmailAddress()).isEqualTo("dirk@holistic.det");
+    assertThat(message).contains("master", "mergeable");
     // We expect the merge result of file b.txt here by looking up the sha hash of its content.
     // If the file is missing (aka not merged correctly) this will throw a MissingObjectException:
     byte[] contentOfFileB = repository.open(repository.resolve("9513e9c76e73f3e562fd8e4c909d0607113c77c6")).getBytes();
     assertThat(new String(contentOfFileB)).isEqualTo("b\ncontent from branch\n");
   }
 
+  @Test
+  public void shouldUseConfiguredCommitMessageTemplate() throws IOException, GitAPIException {
+    GitMergeCommand command = createCommand();
+    MergeCommandRequest request = new MergeCommandRequest();
+    request.setTargetBranch("master");
+    request.setBranchToMerge("mergeable");
+    request.setAuthor(new Person("Dirk Gently", "dirk@holistic.det"));
+    request.setMessageTemplate("simple");
+
+    MergeCommandResult mergeCommandResult = command.merge(request);
+
+    assertThat(mergeCommandResult.isSuccess()).isTrue();
+
+    Repository repository = createContext().open();
+    Iterable<RevCommit> commits = new Git(repository).log().add(repository.resolve("master")).setMaxCount(1).call();
+    RevCommit mergeCommit = commits.iterator().next();
+    String message = mergeCommit.getFullMessage();
+    assertThat(message).isEqualTo("simple");
+  }
+
   @Test
   public void shouldNotMergeConflictingBranches() {
     GitMergeCommand command = createCommand();