Implement lazy JS module initialisation.

chrome/renderer/module_system_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string_piece.h"
 #include "chrome/renderer/module_system.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 148 matching lines @@
       "var caught = false;"
       "try {"
       "  requireNative('assert');"
       "} catch (e) {"
       "  caught = true;"
       "}"
       "assert.AssertTrue(caught);");
   module_system_->Require("test");
 }
 
-TEST_F(ModuleSystemTest, TestLazyObject) {
-  v8::Handle<v8::String> source = v8::String::New("({x: 5})");
-  v8::Handle<v8::Object> lazy_object =
-      ModuleSystem::CreateLazyObject("lazy.js", source);
-  v8::Context::GetCurrent()->Global()->Set(v8::String::New("lazy"),
-                                           lazy_object);
+TEST_F(ModuleSystemTest, TestLazyField) {
+  RegisterModule("lazy",
+      "exports.x = 5;");
+
+  v8::Handle<v8::Object> object = v8::Object::New();
+  v8::Context::GetCurrent()->Global()->Set(v8::String::New("object"), object);
+
+  module_system_->SetLazyField(object, "blah", "lazy", "x");

[not at google - send to devlin, 2012/03/22 00:35:53]

can you do the same sort of thing you did below, though? have a
variable/counter/whatever set in the required code and ensure that it hasn't
been executed before evaluating object.blah?

[koz (OOO until 15th September), 2012/03/22 01:13:01]

That's a good idea for a test. I've added it as a separate test because it's an
orthogonal concern to this test, I think.

+
   RegisterModule("test",
       "var assert = requireNative('assert');"
-      "assert.AssertTrue(lazy.x == 5);"
-      "assert.AssertTrue(lazy.x == 5);");
+      "assert.AssertTrue(object.blah == 5);");
   module_system_->Require("test");
 }
-
-TEST_F(ModuleSystemTest, TestLazyInstanceOnlyGetsEvaledOnce) {
-  v8::Context::GetCurrent()->Global()->Set(v8::String::New("evalCount"),
-                                           v8::Integer::New(0));
-  v8::Handle<v8::String> source = v8::String::New("evalCount++; ({x: 5})");
-  v8::Handle<v8::Object> lazy_object =
-      ModuleSystem::CreateLazyObject("lazy.js", source);
-  v8::Context::GetCurrent()->Global()->Set(v8::String::New("lazy"),
-                                           lazy_object);
-  RegisterModule("test",
-      "var assert = requireNative('assert');"
-      "assert.AssertTrue(evalCount == 0);"
-      "lazy.x;"
-      "assert.AssertTrue(evalCount == 1);"
-      "lazy.x;"
-      "assert.AssertTrue(evalCount == 1);");
-  module_system_->Require("test");
-}