MergeSuperSet: Don't guarantee change is present in output

This sanity check was added I6922b597 to make SubmitStrategyOp able to
fix changes that appeared merged in the repo but not the db. However,
that's not the only case where MergeSuperSet is used: when checking
the ETag of revisions for a merged change, we do want to use the empty
ChangeSet, since once a change is merged we no longer need to consider
dependent changes.

Move the sanity check to MergeOp where it belongs, avoiding an ISE in
GetRevisionActions. Add test coverage for this case.

Change-Id: I2a57553b30eab85355f161914f79b6f30fff4e45

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/revision/RevisionIT.java

@@ -47,8 +47,18 @@ import com.google.gerrit.extensions.common.MergeableInfo;
 import com.google.gerrit.extensions.common.RevisionInfo;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.BinaryResult;
+import com.google.gerrit.extensions.restapi.ETagView;
+import com.google.gerrit.extensions.restapi.IdString;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
 import com.google.gerrit.reviewdb.client.Patch;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gerrit.server.ChangeUtil;
+import com.google.gerrit.server.change.ChangeResource;
+import com.google.gerrit.server.change.GetRevisionActions;
+import com.google.gerrit.server.change.RevisionResource;
+import com.google.gerrit.server.change.Revisions;
+import com.google.gerrit.server.project.ChangeControl;
+import com.google.inject.Inject;
 
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.RefUpdate;
@@ -69,6 +79,15 @@ import java.util.Map;
 @NoHttpd
 public class RevisionIT extends AbstractDaemonTest {
 
+  @Inject
+  private ChangeUtil changeUtil;
+
+  @Inject
+  private GetRevisionActions getRevisionActions;
+
+  @Inject
+  private Revisions revisions;
+
   private TestAccount admin2;
 
   @Before
@@ -618,6 +637,38 @@ public class RevisionIT extends AbstractDaemonTest {
         String.format(PATCH, r.getCommitId().name(), date, r.getChangeId()));
   }
 
+  @Test
+  public void actions() throws Exception {
+    PushOneCommit.Result r = createChange();
+    assertThat(current(r).actions().keySet())
+        .containsExactly("cherrypick", "rebase");
+
+    current(r).review(ReviewInput.approve());
+    assertThat(current(r).actions().keySet())
+        .containsExactly("submit", "cherrypick", "rebase");
+
+    current(r).submit();
+    assertThat(current(r).actions().keySet())
+        .containsExactly("cherrypick");
+  }
+
+  @Test
+  public void actionsETag() throws Exception {
+    PushOneCommit.Result r1 = createChange();
+    PushOneCommit.Result r2 = createChange();
+
+    String oldETag = checkETag(getRevisionActions, r2, null);
+    current(r2).review(ReviewInput.approve());
+    oldETag = checkETag(getRevisionActions, r2, oldETag);
+
+    // Dependent change is included in ETag.
+    current(r1).review(ReviewInput.approve());
+    oldETag = checkETag(getRevisionActions, r2, oldETag);
+
+    current(r2).submit();
+    oldETag = checkETag(getRevisionActions, r2, oldETag);
+  }
+
   private void merge(PushOneCommit.Result r) throws Exception {
     revision(r).review(ReviewInput.approve());
     revision(r).submit();
@@ -634,4 +685,26 @@ public class RevisionIT extends AbstractDaemonTest {
     PushOneCommit push = pushFactory.create(db, admin.getIdent(), testRepo);
     return push.to("refs/drafts/master");
   }
+
+  private RevisionApi current(PushOneCommit.Result r) throws Exception {
+    return gApi.changes().id(r.getChangeId()).current();
+  }
+
+  private RevisionResource parseRevisionResource(PushOneCommit.Result r)
+      throws Exception {
+    PatchSet.Id psId = r.getPatchSetId();
+    List<ChangeControl> ctls = changeUtil.findChanges(
+        Integer.toString(psId.getParentKey().get()), atrScope.get().getUser());
+    assertThat(ctls).hasSize(1);
+    return revisions.parse(
+        new ChangeResource(ctls.get(0)),
+        IdString.fromDecoded(Integer.toString(psId.get())));
+  }
+
+  private String checkETag(ETagView<RevisionResource> view,
+      PushOneCommit.Result r, String oldETag) throws Exception {
+    String eTag = view.getETag(parseRevisionResource(r));
+    assertThat(eTag).isNotEqualTo(oldETag);
+    return eTag;
+  }
 }