Why is there no assertError() function in FlexUnit?

Question

It seems that most XUnit testing frameworks provide assertions for the times when you want to assert that a given operation will thrown an exception (or an Error in AS3 parlance.) Is there some "standard" way of doing this that I am overlooking, which would explain the absence of an assertError() assertion included with FlexUnit?

I know HOW to implement such a thing, and I will probably add it to my FlexUnit (go open source!), but it seems like such a glaring omission that I'm left wondering if I'm just doing it wrong.

Anyone have thoughts on this?

Answer 1

Edit 05/02/2010: I'd now recommend using FlexUnit 4. It uses an extensible metdata system, supports expected exceptions, and also supports running in an integration server environment without the use of AIR.

Edit: You should have a look at fluint, which was built by people who had enough of FlexUnit and it's limitations. It might have some of these types of assertions built in.

I totally agree. In fact, FlexUnit is missing several useful methods (assertEvent, assertArrayEquals, etc). I know you said you know how to implement it, but feel free to use mine:

public static function assertError(message : String, func : Function, errorClass : Class = null, errorMessage : String = null, errorCodes : Array = null) : Error 
{
    _assertionsMade++;

    if (errorClass == null) errorClass = Error;

    try
    {
        func();
    }
    catch(ex : Error)
    {
        if (!(ex is errorClass))
        {
            fail("Expected error of type '" + getQualifiedClassName(errorClass) + "' but was '" + getQualifiedClassName(ex) + "'");
        }

        if (errorMessage != null && ex.message != errorMessage)
        {
            fail("Expected error with message '" + errorMessage + "' but was '" + ex.message + "'");
        }

        if (errorCodes != null && errorCodes.indexOf(ex.errorID) == -1)
        {
            fail("Expected error with errorID '" + errorCodes.join(" or ") + "' but was '" + ex.errorID + "'");
        }

        return ex;
    }

    if (message == null)
    {
        message = "Expected error of type '" + getQualifiedClassName(errorClass) + "' but none was thrown"
    }

    fail(message);

    return null;
}

Answer 2

FlexUnit 4 mates well with hamcrest-as3. hamcrest has error assertion matchers