public void FirstChars() { Assert.AreEqual("", Tools.FirstChars("", 0)); Assert.AreEqual("", Tools.FirstChars("", 3)); Assert.AreEqual("", Tools.FirstChars("123", 0)); Assert.AreEqual("12", Tools.FirstChars("12", 2)); Assert.AreEqual("12", Tools.FirstChars("12", 3)); Assert.AreEqual("12", Tools.FirstChars("123", 2)); }