[debugger] infrastructure for side-effect-free debug-evaluate.

test/debugger/debug/debug-evaluate-no-side-effect.js

+// Copyright 2017 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: --ignition --side-effect-free-debug-evaluate
+
+Debug = debug.Debug
+
+var exception = null;
+let a = 1;
+var object = { property : 2,
+               get getter() { return 3; }
+             };
+var string1 = { toString() { return "x"; } };
+var string2 = { toString() { print("x"); return "x"; } };
+var array = [4, 5];
+var error = new Error();
+
+function set_a() { a = 2; }
+
+function get_a() { return a; }
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Break) return;
+  try {
+    function success(expectation, source) {
+      assertEquals(expectation, exec_state.frame(0).evaluate(source).value());
+    }
+    function fail(source) {
+      assertThrows(() => exec_state.frame(0).evaluate(source), EvalError);
+    }
+    // Simple test.
+    success(3, "1 + 2");
+    // Dymanic load.
+    success(array, "array");
+    // Context load.
+    success(1, "a");
+    // Global and named property load.
+    success(2, "object.property");
+    // Load via read-only getter.
+    success(3, "object.getter");
+    // Implicit call to read-only toString.
+    success("xy", "string1 + 'y'");
+    // Keyed property load.
+    success(5, "array[1]");
+    // Call to read-only function.
+    success(1, "get_a()");
+    // Call to read-only function within try-catch.
+    success(1, "try { get_a() } catch (e) {}");
+    // Call to C++ built-in.
+    success(Math.sin(2), "Math.sin(2)");
+    // Call to whitelisted get accessors.
+    success(3, "'abc'.length");
+    success(2, "array.length");
+    // Test that non-read-only code fails.
+    fail("exception = 1");
+    // Test that calling a non-read-only function fails.
+    fail("set_a()");
+    // Test that implicit call to a non-read-only function fails.
+    fail("string2 + 'y'");
+    // Test that try-catch does not catch the EvalError.
+    fail("try { set_a() } catch (e) {}");
+    // Test that call to set accessor fails.
+    fail("array.length = 4");
+    // Test that call to non-whitelisted get accessor fails.
+    fail("error.stack");
+  } catch (e) {
+    exception = e;
+    print(e, e.stack);
+  };
+};
+
+// Add the debug event listener.
+Debug.setListener(listener);
+
+function f() {
+  debugger;
+};
+
+f();
+
+assertNull(exception);
+assertEquals(1, a);