Compute files with conflicts in merge dry run

Pushed-by: Rene Pfeuffer<rene.pfeuffer@cloudogu.com>
Co-authored-by: René Pfeuffer<rene.pfeuffer@cloudogu.com>

gradle/changelog/merge_conflict.yaml

@@ -0,0 +1,4 @@
+- type: added
+  description: The result of the merge dry-run now contains the names of the files that have conflicts
+- type: added
+  description: Method to compute anchors in diff views can be used in plugins

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

@@ -26,10 +26,25 @@ package sonia.scm.repository.api;
 
 import lombok.Value;
 
+import java.util.Collection;
+
+import static java.util.Collections.emptyList;
+
 /**
  * @since 3.3.0
  */
 @Value
 public class MergePreventReason {
   MergePreventReasonType type;
+
+  Collection<String> affectedPaths;
+
+  public MergePreventReason(MergePreventReasonType type) {
+    this(type, emptyList());
+  }
+
+  public MergePreventReason(MergePreventReasonType type, Collection<String> affectedPaths) {
+    this.type = type;
+    this.affectedPaths = affectedPaths;
+  }
 }

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

@@ -24,7 +24,6 @@
 
 package sonia.scm.repository.spi;
 
-import com.google.common.collect.ImmutableSet;
 import com.google.inject.assistedinject.Assisted;
 import jakarta.inject.Inject;
 import org.eclipse.jgit.api.Git;
@@ -35,9 +34,9 @@ import org.eclipse.jgit.lib.IndexDiff;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.merge.ResolveMerger;
 import org.eclipse.jgit.treewalk.CanonicalTreeParser;
 import org.eclipse.jgit.treewalk.filter.PathFilter;
-import sonia.scm.NotFoundException;
 import sonia.scm.repository.GitRepositoryHandler;
 import sonia.scm.repository.GitWorkingCopyFactory;
 import sonia.scm.repository.InternalRepositoryException;
@@ -52,8 +51,11 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 
+import static java.util.Optional.empty;
+import static java.util.Optional.of;
 import static org.eclipse.jgit.merge.MergeStrategy.RECURSIVE;
 import static sonia.scm.ContextEntry.ContextBuilder.entity;
 import static sonia.scm.NotFoundException.notFound;
@@ -62,7 +64,7 @@ public class GitMergeCommand extends AbstractGitCommand implements MergeCommand
 
   private final GitWorkingCopyFactory workingCopyFactory;
   private final AttributeAnalyzer attributeAnalyzer;
-  private static final Set<MergeStrategy> STRATEGIES = ImmutableSet.of(
+  private static final Set<MergeStrategy> STRATEGIES = Set.of(
     MergeStrategy.MERGE_COMMIT,
     MergeStrategy.FAST_FORWARD_IF_POSSIBLE,
     MergeStrategy.SQUASH,
@@ -117,9 +119,8 @@ public class GitMergeCommand extends AbstractGitCommand implements MergeCommand
         mergePreventReasons.add(new MergePreventReason(MergePreventReasonType.EXTERNAL_MERGE_TOOL));
       }
 
-      if (!isMergeableWithoutFileConflicts(repository, request.getBranchToMerge(), request.getTargetBranch())) {
-        mergePreventReasons.add(new MergePreventReason(MergePreventReasonType.FILE_CONFLICTS));
-      }
+      checkMergeableWithoutFileConflicts(repository, request.getBranchToMerge(), request.getTargetBranch())
+        .ifPresent(mergePreventReasons::add);
 
       return new MergeDryRunCommandResult(mergePreventReasons.isEmpty(), mergePreventReasons);
     } catch (IOException e) {
@@ -127,11 +128,16 @@ public class GitMergeCommand extends AbstractGitCommand implements MergeCommand
     }
   }
 
-  private boolean isMergeableWithoutFileConflicts(Repository repository, String sourceRevision, String targetRevision) throws IOException {
-    return RECURSIVE.newMerger(repository, true).merge(
-      resolveRevisionOrThrowNotFound(repository,sourceRevision),
+  private Optional<MergePreventReason> checkMergeableWithoutFileConflicts(Repository repository, String sourceRevision, String targetRevision) throws IOException {
+    ResolveMerger merger = (ResolveMerger) RECURSIVE.newMerger(repository, true);
+    if (!merger.merge(
+      resolveRevisionOrThrowNotFound(repository, sourceRevision),
       resolveRevisionOrThrowNotFound(repository, targetRevision)
-    );
+    )) {
+      return of(new MergePreventReason(MergePreventReasonType.FILE_CONFLICTS, merger.getUnmergedPaths()));
+    } else {
+      return empty();
+    }
   }
 
   @Override

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

@@ -110,8 +110,10 @@ public class GitMergeCommandTest extends AbstractGitCommandTestBase {
     MergeDryRunCommandResult result = command.dryRun(request);
 
     assertThat(result.isMergeable()).isFalse();
-    assertThat(result.getReasons().size()).isEqualTo(1);
-    assertThat(result.getReasons().stream().toList().get(0).getType()).isEqualTo(MergePreventReasonType.FILE_CONFLICTS);
+    assertThat(result.getReasons()).hasSize(1);
+    MergePreventReason mergePreventReason = result.getReasons().stream().toList().get(0);
+    assertThat(mergePreventReason.getType()).isEqualTo(MergePreventReasonType.FILE_CONFLICTS);
+    assertThat(mergePreventReason.getAffectedPaths()).containsExactly("a.txt");
   }
 
   @Test
@@ -127,7 +129,7 @@ public class GitMergeCommandTest extends AbstractGitCommandTestBase {
     MergeDryRunCommandResult result = command.dryRun(request);
 
     assertThat(result.isMergeable()).isFalse();
-    assertThat(result.getReasons().size()).isEqualTo(1);
+    assertThat(result.getReasons()).hasSize(1);
     assertThat(result.getReasons().stream().toList().get(0).getType()).isEqualTo(MergePreventReasonType.EXTERNAL_MERGE_TOOL);
   }
 
@@ -144,7 +146,7 @@ public class GitMergeCommandTest extends AbstractGitCommandTestBase {
     MergeDryRunCommandResult result = command.dryRun(request);
 
     assertThat(result.isMergeable()).isFalse();
-    assertThat(result.getReasons().size()).isEqualTo(2);
+    assertThat(result.getReasons()).hasSize(2);
     List<MergePreventReason> reasons = result.getReasons().stream().toList();
     assertThat(reasons.get(0).getType()).isEqualTo(MergePreventReasonType.EXTERNAL_MERGE_TOOL);
     assertThat(reasons.get(1).getType()).isEqualTo(MergePreventReasonType.FILE_CONFLICTS);
@@ -379,7 +381,7 @@ public class GitMergeCommandTest extends AbstractGitCommandTestBase {
 
     GitModificationsCommand modificationsCommand = new GitModificationsCommand(createContext());
     List<Added> changes = modificationsCommand.getModifications("master").getAdded();
-    assertThat(changes.size()).isEqualTo(3);
+    assertThat(changes).hasSize(3);
   }
 
 
@@ -468,7 +470,7 @@ public class GitMergeCommandTest extends AbstractGitCommandTestBase {
   }
 
   @Test(expected = NotFoundException.class)
-  public void shouldHandleNotExistingTargetBranchInDryRun() throws IOException {
+  public void shouldHandleNotExistingTargetBranchInDryRun() {
     GitMergeCommand command = createCommand();
     MergeCommandRequest request = new MergeCommandRequest();
     request.setTargetBranch("not_existing");

scm-ui/ui-components/src/index.ts

@@ -143,3 +143,5 @@ export { urls };
 export const getPageFromMatch = urls.getPageFromMatch;
 
 export { default as useGeneratedId } from "./useGeneratedId";
+
+  export { getAnchorId as getDiffAnchorId } from "./repos/diff/helpers";

scm-ui/ui-components/src/repos/JumpToFileButton.tsx

@@ -37,13 +37,17 @@ const Button = styled(Link)`
 type Props = {
   link: string;
   tooltip: string;
+  icon?: string;
+  color?: string;
 };
 
-const JumpToFileButton: FC<Props> = ({ link, tooltip }) => {
+const JumpToFileButton: FC<Props> = ({ link, tooltip, icon, color }) => {
+  const iconToUse = icon ?? "file-code";
+  const colorToUse = color ?? "inherit";
   return (
     <Tooltip message={tooltip} side="top">
       <Button aria-label={tooltip} className="button is-clickable" to={link}>
-        <Icon name="file-code" color="inherit" alt="" />
+        <Icon name={iconToUse} color={colorToUse} alt="" />
       </Button>
     </Tooltip>
   );