Add test coverage for decoding pending reviewers

Pending reviewers are a stored field in the change index. This test
helps ensure that change index implementations properly support decoding
data stored with the pendingreviewers and pendingreviewersbyemail fields.

This new test revealed an error in ElasticChangeIndex, which is now
fixed.

Bug: Issue 6832
Change-Id: Iefa81e4a7c7eab029196d27e38e03ff8488286c1

gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java

@@ -357,7 +357,8 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
       if (source.get(ChangeField.PENDING_REVIEWER.getName()) != null) {
         cd.setPendingReviewers(
             ChangeField.parseReviewerFieldValues(
-                FluentIterable.from(source.get(ChangeField.REVIEWER.getName()).getAsJsonArray())
+                FluentIterable.from(
+                        source.get(ChangeField.PENDING_REVIEWER.getName()).getAsJsonArray())
                     .transform(JsonElement::getAsString)));
       } else if (fields.contains(ChangeField.PENDING_REVIEWER.getName())) {
         cd.setPendingReviewers(ReviewerSet.empty());

gerrit-server/src/test/java/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java

@@ -16,6 +16,7 @@ package com.google.gerrit.server.query.change;
 
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.TruthJUnit.assume;
+import static com.google.gerrit.extensions.client.ListChangesOption.DETAILED_LABELS;
 import static com.google.gerrit.extensions.client.ListChangesOption.REVIEWED;
 import static java.util.concurrent.TimeUnit.HOURS;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
@@ -48,6 +49,7 @@ import com.google.gerrit.extensions.api.groups.GroupInput;
 import com.google.gerrit.extensions.api.projects.ConfigInput;
 import com.google.gerrit.extensions.client.InheritableBoolean;
 import com.google.gerrit.extensions.client.ReviewerState;
+import com.google.gerrit.extensions.common.AccountInfo;
 import com.google.gerrit.extensions.common.ChangeInfo;
 import com.google.gerrit.extensions.common.ChangeMessageInfo;
 import com.google.gerrit.extensions.common.CommentInfo;
@@ -516,6 +518,90 @@ public abstract class AbstractQueryChangesTest extends GerritServerTests {
     assertQuery("is:started", change1);
   }
 
+  private void assertReviewers(Collection<AccountInfo> reviewers, Object... expected)
+      throws Exception {
+    if (expected.length == 0) {
+      assertThat(reviewers).isNull();
+      return;
+    }
+
+    // Convert AccountInfos to strings, either account ID or email.
+    List<String> reviewerIds =
+        reviewers
+            .stream()
+            .map(
+                ai -> {
+                  if (ai._accountId != null) {
+                    return ai._accountId.toString();
+                  }
+                  return ai.email;
+                })
+            .collect(toList());
+    assertThat(reviewerIds).containsExactly(expected);
+  }
+
+  @Test
+  public void restorePendingReviewers() throws Exception {
+    assume().that(getSchemaVersion()).isAtLeast(44);
+    assume().that(notesMigration.readChanges()).isTrue();
+
+    Project.NameKey project = new Project.NameKey("repo");
+    TestRepository<Repo> repo = createProject(project.get());
+    ConfigInput conf = new ConfigInput();
+    conf.enableReviewerByEmail = InheritableBoolean.TRUE;
+    gApi.projects().name(project.get()).config(conf);
+    Change change1 = insert(repo, newChangeWorkInProgress(repo));
+    Account.Id user1 = createAccount("user1");
+    Account.Id user2 = createAccount("user2");
+    String email1 = "email1@example.com";
+    String email2 = "email2@example.com";
+
+    ReviewInput in =
+        ReviewInput.noScore()
+            .reviewer(user1.toString())
+            .reviewer(user2.toString(), ReviewerState.CC, false)
+            .reviewer(email1)
+            .reviewer(email2, ReviewerState.CC, false);
+    gApi.changes().id(change1.getId().get()).revision("current").review(in);
+
+    List<ChangeInfo> changeInfos =
+        assertQuery(newQuery("is:wip").withOption(DETAILED_LABELS), change1);
+    assertThat(changeInfos).isNotEmpty();
+
+    Map<ReviewerState, Collection<AccountInfo>> pendingReviewers =
+        changeInfos.get(0).pendingReviewers;
+    assertThat(pendingReviewers).isNotNull();
+
+    assertReviewers(
+        pendingReviewers.get(ReviewerState.REVIEWER), userId.toString(), user1.toString(), email1);
+    assertReviewers(pendingReviewers.get(ReviewerState.CC), user2.toString(), email2);
+    assertReviewers(pendingReviewers.get(ReviewerState.REMOVED));
+
+    // Pending reviewers may also be presented in the REMOVED state. Toggle the
+    // change to ready and then back to WIP and remove reviewers to produce.
+    assertThat(pendingReviewers.get(ReviewerState.REMOVED)).isNull();
+    gApi.changes().id(change1.getId().get()).setReadyForReview();
+    gApi.changes().id(change1.getId().get()).setWorkInProgress();
+    gApi.changes().id(change1.getId().get()).reviewer(user1.toString()).remove();
+    gApi.changes().id(change1.getId().get()).reviewer(user2.toString()).remove();
+    gApi.changes().id(change1.getId().get()).reviewer(email1).remove();
+    gApi.changes().id(change1.getId().get()).reviewer(email2).remove();
+
+    changeInfos = assertQuery(newQuery("is:wip").withOption(DETAILED_LABELS), change1);
+    assertThat(changeInfos).isNotEmpty();
+
+    pendingReviewers = changeInfos.get(0).pendingReviewers;
+    assertThat(pendingReviewers).isNotNull();
+    assertReviewers(pendingReviewers.get(ReviewerState.REVIEWER));
+    assertReviewers(pendingReviewers.get(ReviewerState.CC));
+    assertReviewers(
+        pendingReviewers.get(ReviewerState.REMOVED),
+        user1.toString(),
+        user2.toString(),
+        email1,
+        email2);
+  }
+
   @Test
   public void byCommit() throws Exception {
     TestRepository<Repo> repo = createProject("repo");