From d268d11ca29b95ce1b8186e6526b58b51f2c913a Mon Sep 17 00:00:00 2001
From: Michael Paulson <michael.b.paulson@gmail.com>
Date: Wed, 27 Jul 2016 13:32:53 -0700
Subject: [PATCH] feat(test): Added mutation testing for scalar values.

This is a port of the tests found in test.cpp
---
 tests/JavaScriptTest.js | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/tests/JavaScriptTest.js b/tests/JavaScriptTest.js
index c89ae85d7..c97ed2d08 100644
--- a/tests/JavaScriptTest.js
+++ b/tests/JavaScriptTest.js
@@ -64,7 +64,10 @@ function main() {
 
   fs.writeFileSync('monsterdata_javascript_wire.mon', new Buffer(fbb.asUint8Array()));
 
-  // Test it:
+  // Tests mutation first.  This will verify that we did not trample any other
+  // part of the byte buffer.
+  testMutation(fbb.dataBuffer());
+  
   testBuffer(fbb.dataBuffer());
 
   test64bit();
@@ -74,6 +77,21 @@ function main() {
   console.log('FlatBuffers test: completed successfully');
 }
 
+function testMutation(bb) {
+  var monster = MyGame.Example.Monster.getRootAsMonster(bb);
+
+  monster.mutate_hp(120);
+  assert.strictEqual(monster.hp(), 120);
+
+  monster.mutate_hp(80);
+  assert.strictEqual(monster.hp(), 80);
+
+  var manaRes = monster.mutate_mana(10);
+  assert.strictEqual(manaRes, false);  // Field was NOT present, because default value.
+
+  // TODO: There is not the availability to mutate structs or vectors.
+}
+
 function testBuffer(bb) {
   assert.ok(MyGame.Example.Monster.bufferHasIdentifier(bb));