Reland "Prevent liveedit on or under generators with open activations"

test/mjsunit/harmony/generators-debug-liveedit.js

Index: test/mjsunit/harmony/generators-debug-liveedit.js
diff --git a/test/mjsunit/harmony/generators-debug-liveedit.js b/test/mjsunit/harmony/generators-debug-liveedit.js
new file mode 100644
index 0000000000000000000000000000000000000000..341ef483c538047d6d8894101377ca7fed0f7c3d
--- /dev/null
+++ b/test/mjsunit/harmony/generators-debug-liveedit.js
@@ -0,0 +1,119 @@
+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --expose-debug-as debug --harmony-generators
+
+var Debug = debug.Debug;
+var LiveEdit = Debug.LiveEdit;
+
+unique_id = 0;
+
+var Generator = (function*(){}).constructor;
+
+function assertIteratorResult(value, done, result) {
+  assertEquals({value: value, done: done}, result);
+}
+
+function MakeGenerator() {
+  // Prevents eval script caching.
+  unique_id++;
+  return Generator('callback',
+      "/* " + unique_id + "*/\n" +
+      "yield callback();\n" +
+      "return 'Cat';\n");
+}
+
+function MakeFunction() {
+  // Prevents eval script caching.
+  unique_id++;
+  return Function('callback',
+      "/* " + unique_id + "*/\n" +
+      "callback();\n" +
+      "return 'Cat';\n");
+}
+
+// First, try MakeGenerator with no perturbations.
+(function(){
+  var generator = MakeGenerator();
+  function callback() {};
+  var iter = generator(callback);
+  assertIteratorResult(undefined, false, iter.next());
+  assertIteratorResult("Cat", true, iter.next());
+})();
+
+function patch(fun, from, to) {
+  function debug() {
+    var log = new Array();
+    var script = Debug.findScript(fun);
+    var pos = script.source.indexOf(from);
+    try {
+      LiveEdit.TestApi.ApplySingleChunkPatch(script, pos, from.length, to,
+                                             log);
+    } finally {
+      print("Change log: " + JSON.stringify(log) + "\n");
+    }
+  }
+  Debug.ExecuteInDebugContext(debug, false);
+}
+
+// Try to edit a MakeGenerator while it's running, then again while it's
+// stopped.
+(function(){
+  var generator = MakeGenerator();
+
+  var gen_patch_attempted = false;
+  function attempt_gen_patch() {
+    assertFalse(gen_patch_attempted);
+    gen_patch_attempted = true;
+    assertThrows(function() { patch(generator, "'Cat'", "'Capybara'") },
+                 LiveEdit.Failure);
+  };
+  var iter = generator(attempt_gen_patch);
+  assertIteratorResult(undefined, false, iter.next());
+  // Patch should not succeed because there is a live generator activation on
+  // the stack.
+  assertIteratorResult("Cat", true, iter.next());
+  assertTrue(gen_patch_attempted);
+
+  // At this point one iterator is live, but closed, so the patch will succeed.
+  patch(generator, "'Cat'", "'Capybara'");
+  iter = generator(function(){});
+  assertIteratorResult(undefined, false, iter.next());
+  // Patch successful.
+  assertIteratorResult("Capybara", true, iter.next());
+
+  // Patching will fail however when a live iterator is suspended.
+  iter = generator(function(){});
+  assertIteratorResult(undefined, false, iter.next());
+  assertThrows(function() { patch(generator, "'Capybara'", "'Tapir'") },
+               LiveEdit.Failure);
+  assertIteratorResult("Capybara", true, iter.next());
+
+  // Try to patch functions with activations inside and outside generator
+  // function activations.  We should succeed in the former case, but not in the
+  // latter.
+  var fun_outside = MakeFunction();
+  var fun_inside = MakeFunction();
+  var fun_patch_attempted = false;
+  var fun_patch_restarted = false;
+  function attempt_fun_patches() {
+    if (fun_patch_attempted) {
+      assertFalse(fun_patch_restarted);
+      fun_patch_restarted = true;
+      return;
+    }
+    fun_patch_attempted = true;
+    // Patching outside a generator activation must fail.
+    assertThrows(function() { patch(fun_outside, "'Cat'", "'Cobra'") },
+                 LiveEdit.Failure);
+    // Patching inside a generator activation may succeed.
+    patch(fun_inside, "'Cat'", "'Koala'");
+  }
+  iter = generator(function() { return fun_inside(attempt_fun_patches) });
+  assertEquals('Cat',
+               fun_outside(function () {
+                 assertIteratorResult('Koala', false, iter.next());
+                 assertTrue(fun_patch_restarted);
+               }));
+})();