implement squash to mergeCommand

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

@@ -16,6 +16,7 @@ import sonia.scm.repository.InternalRepositoryException;
 import sonia.scm.repository.Person;
 import sonia.scm.repository.api.MergeCommandResult;
 import sonia.scm.repository.api.MergeDryRunCommandResult;
+import sonia.scm.repository.api.ScmMergeStrategy;
 
 import java.io.IOException;
 import java.text.MessageFormat;
@@ -61,6 +62,7 @@ public class GitMergeCommand extends AbstractGitCommand implements MergeCommand
     private final String toMerge;
     private final Person author;
     private final String messageTemplate;
+    private final ScmMergeStrategy scmMergeStrategy;
 
     private MergeWorker(Git clone, MergeCommandRequest request) {
       super(clone);
@@ -68,6 +70,7 @@ public class GitMergeCommand extends AbstractGitCommand implements MergeCommand
       this.toMerge = request.getBranchToMerge();
       this.author = request.getAuthor();
       this.messageTemplate = request.getMessageTemplate();
+      this.scmMergeStrategy = request.getScmMergeStrategy();
     }
 
     @Override
@@ -86,11 +89,18 @@ public class GitMergeCommand extends AbstractGitCommand implements MergeCommand
       MergeResult result;
       try {
         ObjectId sourceRevision = resolveRevision(toMerge);
-        result = getClone().merge()
-          .setFastForward(FastForwardMode.NO_FF)
+        org.eclipse.jgit.api.MergeCommand mergeCommand = getClone().merge();
+        mergeCommand
           .setCommit(false) // we want to set the author manually
-          .include(toMerge, sourceRevision)
-          .call();
+          .include(toMerge, sourceRevision);
+
+        if (scmMergeStrategy == ScmMergeStrategy.SQUASH) {
+          mergeCommand.setSquash(true);
+        } else {
+          mergeCommand.setFastForward(FastForwardMode.NO_FF);
+        }
+
+        result = mergeCommand.call();
       } catch (GitAPIException e) {
         throw new InternalRepositoryException(context.getRepository(), "could not merge branch " + toMerge + " into " + target, e);
       }

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

@@ -15,10 +15,12 @@ import org.junit.Test;
 import sonia.scm.NotFoundException;
 import sonia.scm.repository.Person;
 import sonia.scm.repository.api.MergeCommandResult;
+import sonia.scm.repository.api.ScmMergeStrategy;
 import sonia.scm.repository.util.WorkdirProvider;
 import sonia.scm.user.User;
 
 import java.io.IOException;
+import java.util.List;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -211,6 +213,55 @@ public class GitMergeCommandTest extends AbstractGitCommandTestBase {
     assertThat(new String(contentOfFileB)).isEqualTo("b\ncontent from branch\n");
   }
 
+  @Test
+  public void shouldSquashCommitsIfSquashIsEnabled() throws IOException, GitAPIException {
+    GitMergeCommand command = createCommand();
+    MergeCommandRequest request = new MergeCommandRequest();
+    request.setAuthor(new Person("Dirk Gently", "dirk@holistic.det"));
+    request.setBranchToMerge("squash");
+    request.setTargetBranch("master");
+    request.setMessageTemplate("this is a squash");
+    request.setScmMergeStrategy(ScmMergeStrategy.SQUASH);
+
+    MergeCommandResult mergeCommandResult = command.merge(request);
+
+    Repository repository = createContext().open();
+    assertThat(mergeCommandResult.isSuccess()).isTrue();
+
+    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(message).isEqualTo("this is a squash");
+  }
+
+  @Test
+  public void shouldSquashThreeCommitsIntoOne() throws IOException, GitAPIException {
+    GitMergeCommand command = createCommand();
+    MergeCommandRequest request = new MergeCommandRequest();
+    request.setAuthor(new Person("Dirk Gently", "dirk@holistic.det"));
+    request.setBranchToMerge("squash");
+    request.setTargetBranch("master");
+    request.setMessageTemplate("squash three commits");
+    request.setScmMergeStrategy(ScmMergeStrategy.SQUASH);
+    Repository gitRepository = createContext().open();
+    MergeCommandResult mergeCommandResult = command.merge(request);
+
+    assertThat(mergeCommandResult.isSuccess()).isTrue();
+
+    Iterable<RevCommit> commits = new Git(gitRepository).log().add(gitRepository.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(message).isEqualTo("squash three commits");
+
+    GitModificationsCommand modificationsCommand = new GitModificationsCommand(createContext(), repository);
+    List<String> changes = modificationsCommand.getModifications("master").getAdded();
+    assertThat(changes.size()).isEqualTo(3);
+  }
+
   @Test(expected = NotFoundException.class)
   public void shouldHandleNotExistingSourceBranchInMerge() {
     GitMergeCommand command = createCommand();