fix: Fix limitToLast queries with cursors (#1072)

Author: dconeybe

google-cloud-firestore/src/main/java/com/google/cloud/firestore/Query.java

@@ -1289,10 +1289,12 @@ public Query endAt(@Nonnull DocumentSnapshot snapshot) {
  StructuredQuery.Builder buildQuery() {
  StructuredQuery.Builder structuredQuery = buildWithoutClientTranslation();
  if (options.getLimitType().equals(LimitType.Last)) {
- // Apply client translation for limitToLast.
+ structuredQuery.clearOrderBy();
+ structuredQuery.clearStartAt();
+ structuredQuery.clearEndAt();
 
+ // Apply client translation for limitToLast.
  if (!options.getFieldOrders().isEmpty()) {
- structuredQuery.clearOrderBy();
  for (FieldOrder order : options.getFieldOrders()) {
  // Flip the orderBy directions since we want the last results
  order =
@@ -1306,7 +1308,6 @@ StructuredQuery.Builder buildQuery() {
  }
 
  if (options.getStartCursor() != null) {
- structuredQuery.clearEndAt();
  // Swap the cursors to match the flipped query ordering.
  Cursor cursor =
  options
@@ -1318,7 +1319,6 @@ StructuredQuery.Builder buildQuery() {
  }
 
  if (options.getEndCursor() != null) {
- structuredQuery.clearStartAt();
  // Swap the cursors to match the flipped query ordering.
  Cursor cursor =
  options

google-cloud-firestore/src/test/java/com/google/cloud/firestore/it/ITQueryWatchTest.java

@@ -17,6 +17,7 @@
 package com.google.cloud.firestore.it;
 
 import static com.google.cloud.firestore.LocalFirestoreHelper.map;
+import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.Truth.assertWithMessage;
 import static java.util.Arrays.asList;
@@ -26,6 +27,7 @@
 import com.google.cloud.firestore.CollectionReference;
 import com.google.cloud.firestore.DocumentChange;
 import com.google.cloud.firestore.DocumentReference;
+import com.google.cloud.firestore.DocumentSnapshot;
 import com.google.cloud.firestore.EventListener;
 import com.google.cloud.firestore.Firestore;
 import com.google.cloud.firestore.FirestoreException;
@@ -39,6 +41,7 @@
 import com.google.common.base.Joiner;
 import com.google.common.base.Joiner.MapJoiner;
 import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Range;
 import com.google.common.truth.Truth;
 import java.util.ArrayList;
@@ -381,6 +384,112 @@ public void limitToLast() throws Exception {
  listenerAssertions.addedIdsIsAnyOf(emptyList(), asList("doc2", "doc3"));
  }
 
+ /**
+ * Verifies that QuerySnapshot for limitToLast() queries work with startAt when the full limit is
+ * used in the result set.
+ */
+ @Test
+ public void limitToLastWithStartAtFullLimit() throws Exception {
+ for (int i = 0; i < 10; i++) {
+ setDocument("doc" + i, Collections.singletonMap("counter", i));
+ }
+ Query query = randomColl.orderBy("counter").startAt(5).limitToLast(3);
+ assertQueryResultContainsDocsInOrder(query, "doc7", "doc8", "doc9");
+ }
+
+ /**
+ * Verifies that QuerySnapshot for limitToLast() queries work with startAt when the partial limit
+ * is used in the result set.
+ */
+ @Test
+ public void limitToLastWithStartAtPartialLimit() throws Exception {
+ for (int i = 0; i < 10; i++) {
+ setDocument("doc" + i, Collections.singletonMap("counter", i));
+ }
+ Query query = randomColl.orderBy("counter").startAt(8).limitToLast(3);
+ assertQueryResultContainsDocsInOrder(query, "doc8", "doc9");
+ }
+
+ /**
+ * Verifies that QuerySnapshot for limitToLast() queries work with startAfter when the full limit
+ * is used in the result set.
+ */
+ @Test
+ public void limitToLastWithStartAfterFullLimit() throws Exception {
+ for (int i = 0; i < 10; i++) {
+ setDocument("doc" + i, Collections.singletonMap("counter", i));
+ }
+ Query query = randomColl.orderBy("counter").startAfter(5).limitToLast(3);
+ assertQueryResultContainsDocsInOrder(query, "doc7", "doc8", "doc9");
+ }
+
+ /**
+ * Verifies that QuerySnapshot for limitToLast() queries work with startAfter when the partial
+ * limit is used in the result set.
+ */
+ @Test
+ public void limitToLastWithStartAfterPartialLimit() throws Exception {
+ for (int i = 0; i < 10; i++) {
+ setDocument("doc" + i, Collections.singletonMap("counter", i));
+ }
+ Query query = randomColl.orderBy("counter").startAfter(7).limitToLast(3);
+ assertQueryResultContainsDocsInOrder(query, "doc8", "doc9");
+ }
+
+ /** Verifies that QuerySnapshot for limitToLast() queries work with endAt. */
+ @Test
+ public void limitToLastWithEndAt() throws Exception {
+ for (int i = 0; i < 10; i++) {
+ setDocument("doc" + i, Collections.singletonMap("counter", i));
+ }
+ Query query = randomColl.orderBy("counter").endAt(5).limitToLast(3);
+ assertQueryResultContainsDocsInOrder(query, "doc3", "doc4", "doc5");
+ }
+
+ /** Verifies that QuerySnapshot for limitToLast() queries work with endBefore. */
+ @Test
+ public void limitToLastWithEndBefore() throws Exception {
+ for (int i = 0; i < 10; i++) {
+ setDocument("doc" + i, Collections.singletonMap("counter", i));
+ }
+ Query query = randomColl.orderBy("counter").endBefore(5).limitToLast(3);
+ assertQueryResultContainsDocsInOrder(query, "doc2", "doc3", "doc4");
+ }
+
+ /**
+ * Verifies that QuerySnapshot for limitToLast() queries work with both startAt and endAt when the
+ * full limit is used in the result set.
+ */
+ @Test
+ public void limitToLastWithStartAtAndEndAtFullLimit() throws Exception {
+ for (int i = 0; i < 10; i++) {
+ setDocument("doc" + i, Collections.singletonMap("counter", i));
+ }
+ Query query = randomColl.orderBy("counter").startAt(3).endAt(6).limitToLast(3);
+ assertQueryResultContainsDocsInOrder(query, "doc4", "doc5", "doc6");
+ }
+
+ /**
+ * Verifies that QuerySnapshot for limitToLast() queries work with both startAt and endAt when the
+ * partial limit is used in the result set.
+ */
+ @Test
+ public void limitToLastWithStartAtAndEndAtPartialLimit() throws Exception {
+ for (int i = 0; i < 10; i++) {
+ setDocument("doc" + i, Collections.singletonMap("counter", i));
+ }
+ Query query = randomColl.orderBy("counter").startAt(5).endAt(6).limitToLast(3);
+ assertQueryResultContainsDocsInOrder(query, "doc5", "doc6");
+ }
+
+ private static void assertQueryResultContainsDocsInOrder(Query query, String... docIds)
+ throws ExecutionException, InterruptedException {
+ QuerySnapshot snapshot = query.get().get();
+ ImmutableList<String> actualDocIds =
+ snapshot.getDocuments().stream().map(DocumentSnapshot::getId).collect(toImmutableList());
+ assertThat(actualDocIds).containsExactlyElementsIn(docIds).inOrder();
+ }
+
  @Test
  public void shutdownNowTerminatesActiveListener() throws Exception {
  Query query = randomColl.whereEqualTo("foo", "bar");