Inheritance: ExcelFunction
 public void IsTextShouldReturnFalseWhenFirstArgIsNotAString()
 {
     var args = FunctionsHelper.CreateArgs(1);
     var func = new IsText();
     var result = func.Execute(args, _context);
     Assert.IsFalse((bool)result.Result);
 }
 public BuiltInFunctions()
 {
     // Text
     Functions["text"] = new CStr();
     Functions["len"] = new Len();
     Functions["lower"] = new Lower();
     Functions["upper"] = new Upper();
     Functions["left"] = new Left();
     Functions["right"] = new Right();
     Functions["mid"] = new Mid();
     Functions["replace"] = new Replace();
     Functions["substitute"] = new Substitute();
     Functions["concatenate"] = new Concatenate();
     // Numbers
     Functions["int"] = new CInt();
     // Math
     Functions["cos"] = new Cos();
     Functions["cosh"] = new Cosh();
     Functions["power"] = new Power();
     Functions["sqrt"] = new Sqrt();
     Functions["sqrtpi"] = new SqrtPi();
     Functions["pi"] = new Pi();
     Functions["product"] = new Product();
     Functions["ceiling"] = new Ceiling();
     Functions["count"] = new Count();
     Functions["counta"] = new CountA();
     Functions["floor"] = new Floor();
     Functions["sin"] = new Sin();
     Functions["sinh"] = new Sinh();
     Functions["sum"] = new Sum();
     Functions["sumif"] = new SumIf();
     Functions["stdev"] = new Stdev();
     Functions["stdevp"] = new StdevP();
     Functions["subtotal"] = new Subtotal();
     Functions["exp"] = new Exp();
     Functions["log"] = new Log();
     Functions["log10"] = new Log10();
     Functions["max"] = new Max();
     Functions["maxa"] = new Maxa();
     Functions["min"] = new Min();
     Functions["mod"] = new Mod();
     Functions["average"] = new Average();
     Functions["round"] = new Round();
     Functions["rand"] = new Rand();
     Functions["randbetween"] = new RandBetween();
     Functions["tan"] = new Tan();
     Functions["tanh"] = new Tanh();
     Functions["var"] = new Var();
     Functions["varp"] = new VarP();
     // Information
     Functions["isblank"] = new IsBlank();
     Functions["isnumber"] = new IsNumber();
     Functions["istext"] = new IsText();
     Functions["iserror"] = new IsError();
     // Logical
     Functions["if"] = new If();
     Functions["not"] = new Not();
     Functions["and"] = new And();
     Functions["or"] = new Or();
     Functions["true"] = new True();
     // Reference and lookup
     Functions["address"] = new Address();
     Functions["hlookup"] = new HLookup();
     Functions["vlookup"] = new VLookup();
     Functions["lookup"] = new Lookup();
     Functions["match"] = new Match();
     Functions["row"] = new Row();
     Functions["rows"] = new Rows();
     Functions["column"] = new Column();
     Functions["columns"] = new Columns();
     Functions["choose"] = new Choose();
     // Date
     Functions["date"] = new Date();
     Functions["today"] = new Today();
     Functions["now"] = new Now();
     Functions["day"] = new Day();
     Functions["month"] = new Month();
     Functions["year"] = new Year();
     Functions["time"] = new Time();
     Functions["hour"] = new Hour();
     Functions["minute"] = new Minute();
     Functions["second"] = new Second();
 }