From 46f0a3b2f6594cc9a56bfb6a3d92cb20134bdde7 Mon Sep 17 00:00:00 2001
From: Pieter De Baets <pieterdb@fb.com>
Date: Tue, 29 Aug 2017 03:03:10 -0700
Subject: [PATCH] Disambiguate error messages in MethodCall

Reviewed By: fromcelticpark

Differential Revision: D5706581

fbshipit-source-id: 06343e2a41d08a1594eb35bb96cc6dc7bf9e29c6
---
 ReactCommon/cxxreact/MethodCall.cpp | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/ReactCommon/cxxreact/MethodCall.cpp b/ReactCommon/cxxreact/MethodCall.cpp
index 19ed0138886..c125c4bd959 100644
--- a/ReactCommon/cxxreact/MethodCall.cpp
+++ b/ReactCommon/cxxreact/MethodCall.cpp
@@ -13,6 +13,8 @@ namespace react {
 #define REQUEST_PARAMSS 2
 #define REQUEST_CALLID 3
 
+static const char *errorPrefix = "Malformed calls from JS: ";
+
 std::vector<MethodCall> parseMethodCalls(folly::dynamic&& jsonData) throw(std::invalid_argument) {
   if (jsonData.isNull()) {
     return {};
@@ -20,12 +22,12 @@ std::vector<MethodCall> parseMethodCalls(folly::dynamic&& jsonData) throw(std::i
 
   if (!jsonData.isArray()) {
     throw std::invalid_argument(
-      folly::to<std::string>("Did not get valid calls back from JS: ", jsonData.typeName()));
+      folly::to<std::string>(errorPrefix, "input isn't array but ", jsonData.typeName()));
   }
 
   if (jsonData.size() < REQUEST_PARAMSS + 1) {
     throw std::invalid_argument(
-      folly::to<std::string>("Did not get valid calls back from JS: size == ", jsonData.size()));
+      folly::to<std::string>(errorPrefix, "size == ", jsonData.size()));
   }
 
   auto& moduleIds = jsonData[REQUEST_MODULE_IDS];
@@ -35,18 +37,18 @@ std::vector<MethodCall> parseMethodCalls(folly::dynamic&& jsonData) throw(std::i
 
   if (!moduleIds.isArray() || !methodIds.isArray() || !params.isArray()) {
     throw std::invalid_argument(
-      folly::to<std::string>("Did not get valid calls back from JS: ", folly::toJson(jsonData)));
+      folly::to<std::string>(errorPrefix, "not all fields are arrays.\n\n", folly::toJson(jsonData)));
   }
 
   if (moduleIds.size() != methodIds.size() || moduleIds.size() != params.size()) {
     throw std::invalid_argument(
-      folly::to<std::string>("Did not get valid calls back from JS: ", folly::toJson(jsonData)));
+      folly::to<std::string>(errorPrefix, "field sizes are different.\n\n", folly::toJson(jsonData)));
   }
 
   if (jsonData.size() > REQUEST_CALLID) {
     if (!jsonData[REQUEST_CALLID].isNumber()) {
       throw std::invalid_argument(
-        folly::to<std::string>("Did not get valid calls back from JS: %s", folly::toJson(jsonData)));
+        folly::to<std::string>(errorPrefix, "invalid callId", jsonData[REQUEST_CALLID].typeName()));
     }
     callId = jsonData[REQUEST_CALLID].asInt();
   }
@@ -55,7 +57,7 @@ std::vector<MethodCall> parseMethodCalls(folly::dynamic&& jsonData) throw(std::i
   for (size_t i = 0; i < moduleIds.size(); i++) {
     if (!params[i].isArray()) {
       throw std::invalid_argument(
-          folly::to<std::string>("Call argument isn't an array"));
+          folly::to<std::string>(errorPrefix, "method arguments isn't array but ", params[i].typeName()));
     }
 
     methodCalls.emplace_back(