change: 代码整理、定向切换时校验当前状态.

src/test/java/com/serliunx/statemanagement/ManagerTest.java

@@ -1,5 +1,8 @@
 package com.serliunx.statemanagement;
 
+import com.serliunx.statemanagement.manager.DefaultUnidirectionalStateManager;
+import com.serliunx.statemanagement.manager.UnidirectionalStateManager;
+import com.serliunx.statemanagement.support.PrinterState;
 import lombok.extern.slf4j.Slf4j;
 import org.junit.Test;
 
@@ -15,6 +18,10 @@ public class ManagerTest {
 
 	@Test
 	public void testUnidirectionalStateManager() {
+		UnidirectionalStateManager<PrinterState> unidirectionalStateManager =
+				new DefaultUnidirectionalStateManager<>(PrinterState.values());
 
+		System.out.println(unidirectionalStateManager.switchTo(PrinterState.IDLE));
+		System.out.println(unidirectionalStateManager.switchTo(PrinterState.SCANNING));
 	}
 }