Allow configurable exceptions to empty-commit staging restrictionsv3.10-based

In the case of [ChangeLog] tagged commits, it can be appropriate
to stage/merge an empty commit which acts as an update to
Changelog generators, but does not modify code.

Fixes: QTQAINFRA-7343
Change-Id: I173e050866e58c357db4020dc80590d5cc1166bc
Reviewed-by: Jukka Jokiniva <[email protected]>

2 files changed, 56 insertions, 1 deletions

diff --git a/src/main/java/com/googlesource/gerrit/plugins/qtcodereview/QtCherryPickPatch.java b/src/main/java/com/googlesource/gerrit/plugins/qtcodereview/QtCherryPickPatch.java
index 23ec133..ef9c1e5 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/qtcodereview/QtCherryPickPatch.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/qtcodereview/QtCherryPickPatch.java
@@ -26,16 +26,22 @@ import com.google.gerrit.server.update.context.RefUpdateContext;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.Singleton;
+import java.io.IOException;
 import java.sql.Timestamp;
 import java.util.Arrays;
 import java.util.Date;
 import java.util.List;
+import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectInserter;
 import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.PersonIdent;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.storage.file.FileBasedConfig;
+import org.eclipse.jgit.util.FS;
+import org.eclipse.jgit.util.SystemReader;
 
 @Singleton
 public class QtCherryPickPatch {
@@ -145,7 +151,30 @@ public class QtCherryPickPatch {
                 false); // allowConflicts
 
         if (cherryPickCommit.getTree().equals(baseCommit.getTree())) {
-          throw new IntegrationConflictException("Cannot stage change: The patch set is empty.");
+          Config cfg;
+          try {
+            FileBasedConfig userConfig = SystemReader.getInstance().openUserConfig(null, FS.DETECTED);
+            userConfig.load();
+            cfg = userConfig;
+          } catch (IOException | ConfigInvalidException e) {
+            logger.atWarning().withCause(e).log("Could not load user gitconfig");
+            cfg = new Config();
+          }
+          String exceptions = cfg.getString("qtcodereview", null, "emptyCommitExceptions");
+          logger.atInfo().log(
+              "Found empty commit exceptions: %s", exceptions);
+          boolean allowed = false;
+          if (exceptions != null && !exceptions.isEmpty()) {
+            String originalCommitMessage = commitToCherryPick.getFullMessage();
+            allowed =
+                Arrays.stream(exceptions.split(","))
+                    .map(String::trim)
+                    .filter(s -> !s.isEmpty())
+                    .anyMatch(originalCommitMessage::contains);
+          }
+          if (!allowed) {
+            throw new IntegrationConflictException("Cannot stage change: The patch set is empty.");
+          }
         }
 
         boolean patchSetNotChanged = cherryPickCommit.equals(commitToCherryPick);
diff --git a/src/test/java/com/googlesource/gerrit/plugins/qtcodereview/QtStageIT.java b/src/test/java/com/googlesource/gerrit/plugins/qtcodereview/QtStageIT.java
index 5c9b616..dee9a1d 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/qtcodereview/QtStageIT.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/qtcodereview/QtStageIT.java
@@ -23,8 +23,11 @@ import com.google.gerrit.extensions.client.ChangeStatus;
 import java.util.ArrayList;
 import org.apache.http.HttpStatus;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.storage.file.FileBasedConfig;
 import org.eclipse.jgit.transport.PushResult;
 import org.eclipse.jgit.transport.RemoteRefUpdate;
+import org.eclipse.jgit.util.FS;
+import org.eclipse.jgit.util.SystemReader;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -147,6 +150,29 @@ public class QtStageIT extends QtCodeReviewIT {
   }
 
   @Test
+  public void emptyChange_Stage_AllowException() throws Exception {
+
+    // Store exception string
+    FileBasedConfig gitConfig = SystemReader.getInstance().openUserConfig(null, FS.DETECTED);
+    gitConfig.load();
+    gitConfig.setString("qtcodereview", null, "emptyCommitExceptions", "[ChangeLog]");
+    gitConfig.save();
+
+    RevCommit initialHead = getRemoteHead();
+    PushOneCommit.Result c = pushCommit("master", "1st commit]", "afile", "");
+    approve(c.getChangeId());
+    RevCommit stagingHead = qtStage(c);
+    assertApproval(c.getChangeId(), admin);
+
+    // no changes in this commit, but an exception string in commit message
+    c = pushCommit("master", "2nd commit:no content\n[ChangeLog]", "afile", "");
+    approve(c.getChangeId());
+
+    stagingHead = qtStage(c);
+    assertApproval(c.getChangeId(), admin);
+  }
+
+  @Test
   public void emptyChange_Stage_expectFail() throws Exception {
     RevCommit initialHead = getRemoteHead();
     PushOneCommit.Result c = pushCommit("master", "1st commit", "afile", "");