Don't fail on empty bundles (#9140)

Author: schmidt-sebastian

Firestore/Example/Firestore.xcodeproj/project.pbxproj

@@ -109,7 +109,8 @@ NS_SWIFT_NAME(DocumentReference)
  * to be written.
  * @param mergeFields An `NSArray` that contains a list of `NSString` or `FIRFieldPath` elements
  * specifying which fields to merge. Fields can contain dots to reference nested fields within
- * the document. If your input sets any field to an empty dictionary, any nested field is overwritten.
+ * the document. If your input sets any field to an empty dictionary, any nested field is
+ * overwritten.
  */
 - (void)setData:(NSDictionary<NSString *, id> *)documentData mergeFields:(NSArray<id> *)mergeFields;
 

Firestore/Source/Public/FirebaseFirestore/FIRDocumentReference.h

@@ -80,7 +80,8 @@ NS_SWIFT_NAME(Transaction)
  * @param document A reference to the document whose data should be overwritten.
  * @param mergeFields An `NSArray` that contains a list of `NSString` or `FIRFieldPath` elements
  * specifying which fields to merge. Fields can contain dots to reference nested fields within
- * the document. If your input sets any field to an empty dictionary, any nested field is overwritten.
+ * the document. If your input sets any field to an empty dictionary, any nested field is
+ * overwritten.
  * @return This `FIRTransaction` instance. Used for chaining method calls.
  */
 // clang-format off

Firestore/Source/Public/FirebaseFirestore/FIRTransaction.h

@@ -82,7 +82,8 @@ NS_SWIFT_NAME(WriteBatch)
  * @param document A reference to the document whose data should be overwritten.
  * @param mergeFields An `NSArray` that contains a list of `NSString` or `FIRFieldPath` elements
  * specifying which fields to merge. Fields can contain dots to reference nested fields within
- * the document. If your input sets any field to an empty dictionary, any nested field is overwritten.
+ * the document. If your input sets any field to an empty dictionary, any nested field is
+ * overwritten.
  * @return This `FIRWriteBatch` instance. Used for chaining method calls.
  */
 // clang-format off

Firestore/Source/Public/FirebaseFirestore/FIRWriteBatch.h

@@ -95,8 +95,8 @@ Timestamp DecodeTimestamp(JsonReader& reader, const json& version) {
     }
   } else {
     decoded = TimestampInternal::FromUntrustedSecondsAndNanos(
-        reader.RequiredInt<int64_t>("seconds", version),
-        reader.RequiredInt<int32_t>("nanos", version));
+        reader.OptionalInt<int64_t>("seconds", version, 0),
+        reader.OptionalInt<int32_t>("nanos", version, 0));
   }
 
   if (!decoded.ok()) {

Firestore/core/src/bundle/bundle_serializer.cc

@@ -326,6 +326,24 @@ class BundleReaderTest : public ::testing::Test {
   std::vector<std::string> elements_;
 };
 
+TEST_F(BundleReaderTest, ReadsEmptyBundle) {
+  ProtoBundleMetadata metadata;
+  metadata.set_id("bundle-1");
+  metadata.set_version(1);
+  metadata.set_total_documents(0);
+  metadata.mutable_create_time();  // No seconds/nanos
+  metadata.set_total_bytes(0);
+  ProtoBundleElement element;
+  *element.mutable_metadata() = metadata;
+
+  std::string metadata_str;
+  MessageToJsonString(element, &metadata_str);
+  std::string bundle = std::to_string(metadata_str.size()) + metadata_str;
+
+  BundleReader reader(bundle_serializer, ToByteStream(bundle));
+  VerifyFullBundleParsed(reader, "bundle-1", testutil::Version(0));
+}
+
 TEST_F(BundleReaderTest, ReadsQueryAndDocument) {
   AddNamedQuery(LimitQuery());
   AddNamedQuery(LimitToLastQuery());