47 lines
1.6 KiB
JavaScript
47 lines
1.6 KiB
JavaScript
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// Copyright 2020 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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var Debug = debug.Debug;
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var frame;
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Debug.setListener(function (event, exec_state, event_data, data) {
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if (event == Debug.DebugEvent.Break) {
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frame = exec_state.frame(0);
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// Try changing the value, which hasn't yet been initialized.
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assertEquals(3, frame.evaluate("result = 3").value());
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assertEquals(3, frame.evaluate("result").value());
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}
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});
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function makeCounter() {
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// If the variable `result` were stack-allocated, it would be 3 at this point
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// due to the debugging activity during function entry. However, for a
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// heap-allocated variable, the debugger evaluated `result = 3` in a temporary
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// scope instead and had no effect on this variable.
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assertEquals(undefined, result);
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var result = 0;
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// Regardless of how `result` is allocated, it should now be initialized.
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assertEquals(0, result);
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// Close over `result` to cause it to be heap-allocated.
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return () => ++result;
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}
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// Break on entry to a function which includes heap-allocated variables.
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%ScheduleBreak();
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makeCounter();
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// Check the frame state which was collected during the breakpoint.
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assertEquals(1, frame.localCount());
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assertEquals('result', frame.localName(0));
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assertEquals(undefined, frame.localValue(0).value());
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assertEquals(3, frame.scopeCount());
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assertEquals(debug.ScopeType.Local, frame.scope(0).scopeType());
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assertEquals(debug.ScopeType.Script, frame.scope(1).scopeType());
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assertEquals(debug.ScopeType.Global, frame.scope(2).scopeType());
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