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

test/debugger/debug/debug-evaluate-readonly.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 --readonly-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];
+
+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 {
+    // Simple test.
+    assertEquals(3, exec_state.frame(0).evaluate("1 + 2").value());
+    // Context load.
+    assertEquals(1, exec_state.frame(0).evaluate("a").value());
+    // Global and named property load.
+    assertEquals(2, exec_state.frame(0).evaluate("object.property").value());
+    // Load via read-only getter.
+    assertEquals(3, exec_state.frame(0).evaluate("object.getter").value());
+    // Implicit call to read-only toString.
+    assertEquals("xy", exec_state.frame(0).evaluate("string1 + 'y'").value());
+    // Keyed property load.
+    assertEquals(5, exec_state.frame(0).evaluate("array[1]").value());
+    // Call to read-only function.
+    assertEquals(1, exec_state.frame(0).evaluate("get_a()").value());
+    // Call to read-only function within try-catch.
+    assertEquals(1, exec_state.frame(0).evaluate("try { get_a() } catch (e) {}").value());
+    // Test that non-read-only code fails.
+    assertThrows(() => exec_state.frame(0).evaluate("exception = 1"), EvalError);
+    // Test that calling a non-read-only function fails.
+    assertThrows(() => exec_state.frame(0).evaluate("set_a()"), EvalError);
+    // Test that implicit call to a non-read-only function fails.
+    assertThrows(() => exec_state.frame(0).evaluate("string2 + 'y'"), EvalError);
+    // Test that try-catch does not catch the EvalError.
+    assertThrows(() => exec_state.frame(0).evaluate("try { set_a() } catch (e) {}"), EvalError);
+  } 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);