v8/test/mjsunit/debug-stepin-builtin-callback.js

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// Flags: --expose-debug-as debug

// Test stepping into callbacks passed to builtin functions.

Debug = debug.Debug

var exception = false;

function array_listener(event, exec_state, event_data, data) {
  try {
    if (event == Debug.DebugEvent.Break) {
      if (breaks == 0) {
        exec_state.prepareStep(Debug.StepAction.StepIn, 2);
        breaks = 1;
      } else if (breaks <= 3) {
        breaks++;
        // Check whether we break at the expected line.
        print(event_data.sourceLineText());
        assertTrue(event_data.sourceLineText().indexOf("Expected to step") > 0);
        exec_state.prepareStep(Debug.StepAction.StepIn, 3);
      }
    }
  } catch (e) {
    exception = true;
  }
};

function cb_false(num) {
  print("element " + num);  // Expected to step to this point.
  return false;
}

function cb_true(num) {
  print("element " + num);  // Expected to step to this point.
  return true;
}

function cb_reduce(a, b) {
  print("elements " + a + " and " + b);  // Expected to step to this point.
  return a + b;
}

var a = [1, 2, 3, 4];

Debug.setListener(array_listener);

var breaks = 0;
debugger;
a.forEach(cb_true);
assertFalse(exception);
assertEquals(4, breaks);

breaks = 0;
debugger;
a.some(cb_false);
assertFalse(exception);
assertEquals(4, breaks);

breaks = 0;
debugger;
a.every(cb_true);
assertEquals(4, breaks);
assertFalse(exception);

breaks = 0;
debugger;
a.map(cb_true);
assertFalse(exception);
assertEquals(4, breaks);

breaks = 0;
debugger;
a.filter(cb_true);
assertFalse(exception);
assertEquals(4, breaks);

breaks = 0;
debugger;
a.reduce(cb_reduce);
assertFalse(exception);
assertEquals(4, breaks);

breaks = 0;
debugger;
a.reduceRight(cb_reduce);
assertFalse(exception);
assertEquals(4, breaks);

Debug.setListener(null);


// Test two levels of builtin callbacks:
// Array.forEach calls a callback function, which by itself uses
// Array.forEach with another callback function.

function second_level_listener(event, exec_state, event_data, data) {
  try {
    if (event == Debug.DebugEvent.Break) {
      if (breaks == 0) {
        exec_state.prepareStep(Debug.StepAction.StepIn, 3);
        breaks = 1;
      } else if (breaks <= 16) {
        breaks++;
        // Check whether we break at the expected line.
        assertTrue(event_data.sourceLineText().indexOf("Expected to step") > 0);
        // Step two steps further every four breaks to skip the
        // forEach call in the first level of recurision.
        var step = (breaks % 4 == 1) ? 6 : 3;
        exec_state.prepareStep(Debug.StepAction.StepIn, step);
      }
    }
  } catch (e) {
    exception = true;
  }
};

function cb_foreach(num) {
  a.forEach(cb_true);
  print("back to the first level of recursion.");
}

Debug.setListener(second_level_listener);

breaks = 0;
debugger;
a.forEach(cb_foreach);
assertFalse(exception);
assertEquals(17, breaks);

Debug.setListener(null);