feat: Add toString methods to classes comprising WriteBatch (#1281)

* feat: Add toString methods to classes comprising WriteBatch

* feat: Add toString methods to classes comprising WriteBatch
take2: use dynamic class names

* feat: Add toString methods to classes comprising WriteBatch
take3:
- fix formatting
- add unit tests

* feat: Add toString methods to classes comprising WriteBatch
take4: address review comments

* feat: Add toString methods to classes comprising WriteBatch
take5: address review comment

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

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

@@ -448,4 +448,11 @@ public boolean equals(Object obj) {
   public int hashCode() {
     return Objects.hash(rpcContext, docRef, fields);
   }
+
+  @Override
+  public String toString() {
+    return String.format(
+        "%s{doc=%s, fields=%s, readTime=%s, updateTime=%s, createTime=%s}",
+        getClass().getSimpleName(), docRef, fields, readTime, updateTime, createTime);
+  }
 }

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

@@ -53,6 +53,11 @@ static class WriteOperation {
       this.documentReference = documentReference;
       this.write = write;
     }
+
+    @Override
+    public String toString() {
+      return String.format("WriteOperation{write=%s, doc=%s}", write, documentReference);
+    }
   }
 
   final FirestoreImpl firestore;
@@ -646,4 +651,10 @@ List<WriteOperation> getWrites() {
   public int getMutationsSize() {
     return writes.size();
   }
+
+  @Override
+  public String toString() {
+    return String.format(
+        "%s{writes=%s, committed=%s}", getClass().getSimpleName(), writes, committed);
+  }
 }

google-cloud-firestore/src/test/java/com/google/cloud/firestore/ToStringTest.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.cloud.firestore;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.cloud.Timestamp;
+import com.google.cloud.firestore.spi.v1.FirestoreRpc;
+import com.google.firestore.v1.Value;
+import java.util.Collections;
+import java.util.Map;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mockito;
+import org.mockito.Spy;
+import org.mockito.runners.MockitoJUnitRunner;
+
+/** @author Eran Leshem */
+@RunWith(MockitoJUnitRunner.class)
+public class ToStringTest {
+
+  @Spy
+  private final FirestoreImpl firestoreMock =
+      new FirestoreImpl(
+          FirestoreOptions.newBuilder().setProjectId("test-project").build(),
+          Mockito.mock(FirestoreRpc.class));
+
+  private WriteBatch batch;
+  private DocumentReference documentReference;
+
+  @Before
+  public void before() {
+    batch = firestoreMock.batch();
+    documentReference = firestoreMock.document("coll/doc");
+  }
+
+  @Test
+  public void testDocumentSnapshot() {
+    Map<String, Value> fields =
+        Collections.singletonMap(
+            "key123",
+            UserDataConverter.encodeValue(
+                FieldPath.of("key456"),
+                CustomClassMapper.convertToPlainJavaTypes("value789"),
+                UserDataConverter.NO_DELETES));
+    String toStringResult =
+        new DocumentSnapshot(
+                null,
+                documentReference,
+                fields,
+                Timestamp.ofTimeMicroseconds(1),
+                Timestamp.ofTimeMicroseconds(2),
+                Timestamp.ofTimeMicroseconds(3))
+            .toString();
+    assertThat(toStringResult).startsWith("DocumentSnapshot{");
+    assertThat(toStringResult).containsMatch("doc=DocumentReference\\{path=.*/documents/coll/doc}");
+    assertThat(toStringResult).containsMatch("(?s)fields=\\{key123=string_value:.*value789.*}");
+    assertThat(toStringResult).contains("readTime=1970-01-01T00:00:00.000001000Z");
+    assertThat(toStringResult).contains("updateTime=1970-01-01T00:00:00.000002000Z");
+    assertThat(toStringResult).contains("createTime=1970-01-01T00:00:00.000003000Z");
+    assertThat(toStringResult).endsWith("}");
+  }
+
+  @Test
+  public void testWriteOperation() {
+    String toStringResult =
+        new UpdateBuilder.WriteOperation(
+                documentReference,
+                DocumentSnapshot.fromObject(
+                        null,
+                        documentReference,
+                        Collections.singletonMap("key", "value"),
+                        UserDataConverter.NO_DELETES)
+                    .toPb())
+            .toString();
+    assertThat(toStringResult).startsWith("WriteOperation{");
+    assertThat(toStringResult)
+        .containsMatch("(?s)write=update\\s*\\{\\s*name:.*/documents/coll/doc.*}");
+    assertThat(toStringResult).containsMatch("doc=DocumentReference\\{path=.*/documents/coll/doc}");
+    assertThat(toStringResult).endsWith("}");
+  }
+
+  @Test
+  public void testWriteBatch() {
+    batch.update(documentReference, Collections.singletonMap("key", "value"));
+    String toStringResult = batch.toString();
+    assertThat(toStringResult).startsWith("WriteBatch{");
+    assertThat(toStringResult)
+        .containsMatch("(?s)writes=\\[WriteOperation\\{write=update.*/documents/coll/doc.*}]");
+    assertThat(toStringResult).contains("committed=false");
+    assertThat(toStringResult).endsWith("}");
+  }
+}