client: fix assertion triggered on data decoding failure

After decoding response data we check if the decoder advanced the
iterator to the end of the raw data. However, that's not true when
someone tries to decode data with non-matching format. The commit fixes
the assertion - we should check iterator only if data was successfully
decoded.

Closes #99

Author: drewdzzz

src/Client/ResponseReader.hpp

@@ -106,7 +106,7 @@ struct Data {
 	{
 		it_t itr = iters.first;
 		bool ok = mpp::decode(itr, tuples);
-		assert(itr == iters.second);
+		assert(!ok || itr == iters.second);
 		return ok;
 	}
 

test/ClientTest.cpp

@@ -1093,6 +1093,42 @@ test_dead_connection_wait(Connector<BUFFER, NetProvider> &client)
 #endif
 }
 
+/**
+ * Test for miscellaneous issues related to response decoding.
+ */
+template <class BUFFER, class NetProvider>
+void
+response_decoding(Connector<BUFFER, NetProvider> &client)
+{
+	TEST_INIT(0);
+
+	Connection<Buf_t, NetProvider> conn(client);
+	int rc = test_connect(client, conn, localhost, port);
+	fail_unless(rc == 0);
+
+	TEST_CASE("decode data with non-matching format");
+	rid_t f = conn.call("remote_uint", std::make_tuple());
+	client.wait(conn, f, WAIT_TIMEOUT);
+	fail_unless(conn.futureIsReady(f));
+	std::optional<Response<Buf_t>> response = conn.getResponse(f);
+
+	fail_unless(response.has_value());
+	fail_unless(response->body.data.has_value());
+
+	std::string str;
+	unsigned num;
+	std::tuple<std::string> arr_of_str;
+	std::tuple<unsigned> arr_of_num;
+	/* Try to decode data with non-matching format. */
+	fail_if(response->body.data->decode(str));
+	fail_if(response->body.data->decode(num));
+	fail_if(response->body.data->decode(arr_of_str));
+	/* We should successfully decode data after all. */
+	fail_unless(response->body.data->decode(arr_of_num));
+
+	client.close(conn);
+}
+
 int main()
 {
 #ifdef TNTCXX_ENABLE_SSL
@@ -1141,5 +1177,6 @@ int main()
 	::test_sigpipe(client);
 #endif
 	::test_dead_connection_wait(client);
+	response_decoding(client);
 	return 0;
 }