### Question:
StateMachine { public boolean setIf(T newState, Predicate<T> predicate) { checkState(!Thread.holdsLock(lock), "Cannot set state while holding the lock"); requireNonNull(newState, "newState is null"); while (true) { T currentState = get(); if (currentState.equals(newState)) { return false; } if (!predicate.test(currentState)) { return false; } if (compareAndSet(currentState, newState)) { return true; } } } StateMachine(String name, Executor executor, T initialState);  StateMachine(String name, Executor executor, T initialState, Iterable<T> terminalStates); @SuppressWarnings("FieldAccessNotGuarded") T get(); T set(T newState); T trySet(T newState); boolean setIf(T newState, Predicate<T> predicate); boolean compareAndSet(T expectedState, T newState); ListenableFuture<T> getStateChange(T currentState); void addStateChangeListener(StateChangeListener<T> stateChangeListener); @Override String toString();  }### Answer:
@Test public void testSetIf() throws Exception { StateMachine<State> stateMachine = new StateMachine<>("test", executor, State.BREAKFAST, ImmutableSet.of(State.DINNER)); assertEquals(stateMachine.get(), State.BREAKFAST); assertNoStateChange(stateMachine, () -> assertFalse(stateMachine.setIf(State.LUNCH, currentState -> { assertEquals(currentState, State.BREAKFAST); return false; }))); assertStateChange(stateMachine, () -> assertTrue(stateMachine.setIf(State.LUNCH, currentState -> { assertEquals(currentState, State.BREAKFAST); return true; })), State.LUNCH); assertNoStateChange(stateMachine, () -> assertFalse(stateMachine.setIf(State.LUNCH, currentState -> { assertEquals(currentState, State.LUNCH); return false; }))); assertNoStateChange(stateMachine, () -> assertFalse(stateMachine.setIf(State.LUNCH, currentState -> { assertEquals(currentState, State.LUNCH); return true; }))); assertStateChange(stateMachine, () -> stateMachine.setIf(State.DINNER, currentState -> true), State.DINNER); assertNoStateChange(stateMachine, () -> { try { stateMachine.setIf(State.LUNCH, currentState -> true); fail("expected IllegalStateException"); } catch (IllegalStateException expected) { } }); assertNoStateChange(stateMachine, () -> stateMachine.setIf(State.LUNCH, currentState -> false)); assertNoStateChange(stateMachine, () -> stateMachine.setIf(State.DINNER, currentState -> true)); }