@Test public void testPush() { sp.push("PUSH", "ONE"); sp.push("PUSH", "TWO"); sp.push("PUSH", "THREE"); sp.out("PUSH", "FOUR"); assertEquals("THREE", sp.rdp("PUSH")); assertEquals("THREE", sp.inp("PUSH")); assertEquals("TWO", sp.inp("PUSH")); assertEquals("ONE", sp.inp("PUSH")); assertEquals("FOUR", sp.inp("PUSH")); assertNull(sp.rdp("PUSH")); }