[debugger] Various break-related functionality in test wrapper

test/debugger/debugger/debug-step-4.js

+// Copyright 2016 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.
+
+const Debug = new DebugWrapper();
+Debug.enable();
+
+// Tests how debugger can step over not necessarily in the top frame.
+
+// Simple 3 functions, that protocol their execution state in global
+// variable state.
+var state;
+
+function f() {
+  var a = 1978;
+  for (state[2] = 0; state[2] < 3; state[2]++) {
+    void String(a);
+  }
+}
+function g() {
+  for (state[1] = 0; state[1] < 3; state[1]++) {
+    f();
+  }
+}
+function h() {
+  state = [-1, -1, -1];
+  for (state[0] = 0; state[0] < 3; state[0]++) {
+    g();
+  }
+}
+
+function TestCase(expected_final_state) {
+  var listener_exception = null;
+  var state_snapshot;
+  var listener_state;
+  var bp;
+
+  function listener(event, exec_state, event_data, data) {
+    const location = exec_state.frames[0].location
+    print("Here (" + event + "/" + listener_state + "): " +
+          location.lineNumber + ":" + location.columnNumber);
+    try {
+      if (event == Debug.DebugEvent.Break) {
+        if (listener_state == 0) {
+          Debug.clearBreakPoint(bp);
+          Debug.stepOver();
+          listener_state = 1;
+        } else if (listener_state == 1) {
+          state_snapshot = String(state);
+          print("State: " + state_snapshot);
+          Debug.setListener(null);
+          listener_state = 2;
+        }
+      }
+    } catch (e) {
+      listener_exception = e;
+    }
+  }
+
+
+  // Add the debug event listener.
+  listener_state = 0;
+  Debug.setListener(listener);
+  bp = Debug.setBreakPoint(f, 1);
+
+  h();
+  Debug.setListener(null);
+  if (listener_exception !== null) {
+    print("Exception caught: " + listener_exception);
+    assertUnreachable();
+  }
+
+  assertEquals(expected_final_state, state_snapshot);
+}
+
+
+// Warm-up -- make sure all is compiled and ready for breakpoint.
+h();
+
+TestCase("0,0,-1");