public void CanMultiply()
 {
     var engine = new Engine();
       engine.Digit(2);
       engine.Times();
       engine.Digit(3);
       engine.Equals();
       Assert.AreEqual(6, engine.Value);
 }
 public void PrecedenceTest2()
 {
     var engine = new Engine();
       engine.Digit(1);
       engine.Times();
       engine.Digit(2);
       engine.Plus();
       engine.Digit(3);
       engine.Times();
       engine.Digit(4);
       engine.Equals();
       Assert.AreEqual(20, engine.Value);
 }
 public void CanEnterNegativeDecimals()
 {
     var engine = new Engine();
       engine.Minus();
       engine.Point();
       engine.Digit(1);
       Assert.AreEqual(-0.1, engine.Value);
       engine.Digit(2);
       Assert.AreEqual(-0.12, engine.Value);
       engine.Times();
       Assert.AreEqual(-0.12, engine.Value);
       engine.Digit(3);
       engine.Equals();
       Assert.AreEqual(-0.36, engine.Value);
 }