def test_peek_returns_highest_priority_value():
heap = Heap(5, default_priority_function)
heap.insert(1)
heap.insert(5)
heap.insert(6)
heap.insert(2)
result = heap.peek()
assert result == 6
def test_heap_behaves_correctly_with_duplicate_values():
heap = Heap(5, default_priority_function)
heap.insert(1)
heap.insert(5)
heap.insert(3)
heap.insert(5)
assert heap.extract() == 5
assert heap.extract() == 5
assert heap.extract() == 3
assert heap.peek() == 1
