impl(bigquery): Fixed jobs and tables response for empty use case (#14938)

Author: jsrinnn

google/cloud/bigquery/v2/minimal/internal/job_response.cc

@@ -37,7 +37,7 @@ bool valid_list_format_job(nlohmann::json const& j) {
 }
 
 bool valid_jobs_list(nlohmann::json const& j) {
-  return (j.contains("kind") && j.contains("etag") && j.contains("jobs"));
+  return (j.contains("kind") && j.contains("etag"));
 }
 
 StatusOr<nlohmann::json> parse_json(std::string const& payload) {
@@ -95,9 +95,16 @@ StatusOr<ListJobsResponse> ListJobsResponse::BuildFromHttpResponse(
 
   ListJobsResponse result;
   result.http_response = http_response;
-
   result.kind = json->value("kind", "");
   result.etag = json->value("etag", "");
+
+  if (!(*json).contains("jobs")) {
+    // For accounts with no jobs, "jobs" json key will not be returned.
+    // Only "kind" and "etag" keys are returned. Since the server returns
+    // a 200 in this case, we need to do the same.
+    return result;
+  }
+
   result.next_page_token = json->value("nextPageToken", "");
 
   for (auto const& kv : json->at("jobs").items()) {

google/cloud/bigquery/v2/minimal/internal/job_response_test.cc

@@ -126,6 +126,20 @@ TEST(GetJobResponseTest, InvalidJob) {
                                      HasSubstr("Not a valid Json Job object")));
 }
 
+TEST(ListJobsResponseTest, NoJobs) {
+  BigQueryHttpResponse http_response;
+  http_response.payload =
+      R"({"kind": "kind-1",
+          "etag": "tag-1"})";
+  auto const list_jobs_response =
+      ListJobsResponse::BuildFromHttpResponse(http_response);
+
+  ASSERT_STATUS_OK(list_jobs_response);
+  EXPECT_FALSE(list_jobs_response->http_response.payload.empty());
+  EXPECT_EQ(list_jobs_response->kind, "kind-1");
+  EXPECT_EQ(list_jobs_response->etag, "tag-1");
+}
+
 TEST(ListJobsResponseTest, SuccessMultiplePages) {
   BigQueryHttpResponse http_response;
   http_response.payload =
@@ -225,16 +239,6 @@ TEST(ListJobsResponseTest, InvalidJson) {
                        HasSubstr("Error parsing Json from response payload")));
 }
 
-TEST(ListJobsResponseTest, InvalidJobList) {
-  BigQueryHttpResponse http_response;
-  http_response.payload =
-      R"({"kind": "jkind",
-          "etag": "jtag"})";
-  auto const response = ListJobsResponse::BuildFromHttpResponse(http_response);
-  EXPECT_THAT(response, StatusIs(StatusCode::kInternal,
-                                 HasSubstr("Not a valid Json JobList object")));
-}
-
 TEST(ListJobsResponseTest, InvalidListFormatJob) {
   BigQueryHttpResponse http_response;
   http_response.payload =

google/cloud/bigquery/v2/minimal/internal/table_response.cc

@@ -36,7 +36,7 @@ bool valid_list_format_table(nlohmann::json const& j) {
 }
 
 bool valid_tables_list(nlohmann::json const& j) {
-  return (j.contains("kind") && j.contains("etag") && j.contains("tables"));
+  return (j.contains("kind") && j.contains("etag"));
 }
 
 StatusOr<nlohmann::json> parse_json(std::string const& payload) {
@@ -88,6 +88,11 @@ StatusOr<ListTablesResponse> ListTablesResponse::BuildFromHttpResponse(
   result.next_page_token = json->value("nextPageToken", "");
   result.total_items = json->value("totalItems", 0);
 
+  if (result.total_items == 0) {
+    // If the dataset is empty, server does not return the "tables" key.
+    return result;
+  }
+
   for (auto const& kv : json->at("tables").items()) {
     auto const& json_list_format_table_obj = kv.value();
     if (!valid_list_format_table(json_list_format_table_obj)) {

google/cloud/bigquery/v2/minimal/internal/table_response_test.cc

@@ -64,6 +64,20 @@ TEST(GetTableResponseTest, InvalidTable) {
                                  HasSubstr("Not a valid Json Table object")));
 }
 
+TEST(ListTablesResponseTest, EmptyDatasetNoTables) {
+  BigQueryHttpResponse http_response;
+  http_response.payload =
+      R"({"kind":"kind-1", "etag":"tag-1", "totalItems":0})";
+  auto const list_tables_response =
+      ListTablesResponse::BuildFromHttpResponse(http_response);
+  ASSERT_STATUS_OK(list_tables_response);
+  EXPECT_FALSE(list_tables_response->http_response.payload.empty());
+  EXPECT_EQ(list_tables_response->kind, "kind-1");
+  EXPECT_EQ(list_tables_response->etag, "tag-1");
+  EXPECT_EQ(list_tables_response->total_items, 0);
+  EXPECT_THAT(list_tables_response->next_page_token, "");
+}
+
 TEST(ListTablesResponseTest, SuccessMultiplePages) {
   BigQueryHttpResponse http_response;
   auto tables_json_txt =
@@ -133,18 +147,6 @@ TEST(ListTablesResponseTest, InvalidJson) {
                        HasSubstr("Error parsing Json from response payload")));
 }
 
-TEST(ListTablesResponseTest, InvalidTableList) {
-  BigQueryHttpResponse http_response;
-  http_response.payload =
-      R"({"kind": "dkind",
-          "etag": "dtag"})";
-  auto const response =
-      ListTablesResponse::BuildFromHttpResponse(http_response);
-  EXPECT_THAT(response,
-              StatusIs(StatusCode::kInternal,
-                       HasSubstr("Not a valid Json TableList object")));
-}
-
 TEST(ListTablesResponseTest, InvalidListFormatTable) {
   BigQueryHttpResponse http_response;
   http_response.payload =