Fix flag to switch write protection of code pages on/off.

runtime/vm/object_test.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/simulator.h"
 #include "vm/symbols.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
+DECLARE_FLAG(bool, write_protect_code);
+
 static RawLibrary* CreateDummyLibrary(const String& library_name) {
   return Library::New(library_name);
 }
 
 
 static RawClass* CreateDummyClass(const String& class_name,
                                   const Script& script) {
   const Class& cls = Class::Handle(
       Class::New(class_name, script, Scanner::kNoSourcePos));
   cls.set_is_synthesized_class();  // Dummy class for testing.
@@ skipping 2449 matching lines @@
   intptr_t retval = 0;
 #if defined(USING_SIMULATOR)
   retval = bit_copy<intptr_t, int64_t>(Simulator::Current()->Call(
       static_cast<int32_t>(entry_point), 0, 0, 0, 0));
 #else
   typedef intptr_t (*IncrementCode)();
   retval = reinterpret_cast<IncrementCode>(entry_point)();
 #endif
   EXPECT_EQ(3, retval);
   EXPECT_EQ(instructions.raw(), Instructions::FromEntryPoint(entry_point));
+  if (!FLAG_write_protect_code) {
+    // Since this test is expected to crash, crash if write protection of code
+    // is switched off.
+    OS::DebugBreak();
+  }
 }
 
 
 // Test for Embedded String object in the instructions.
 TEST_CASE(EmbedStringInCode) {
   extern void GenerateEmbedStringInCode(Assembler* assembler, const char* str);
   const char* kHello = "Hello World!";
   word expected_length = static_cast<word>(strlen(kHello));
   Assembler _assembler_;
   GenerateEmbedStringInCode(&_assembler_, kHello);
@@ skipping 1508 matching lines @@
   // Simple map.
   //
   // TODO(turnidge): Consider showing something like: {1: 2, 2: 'otter'}
   result = Dart_GetField(lib, NewString("simple_map"));
   EXPECT_VALID(result);
   obj ^= Api::UnwrapHandle(result);
   EXPECT_STREQ("Instance of '_LinkedHashMap'", obj.ToUserCString());
 }
 
 }  // namespace dart