Re: 100%% Method Testing and Generating Unit Tests

>
> Is that a fair summary?
>
>    David Saff
>
> On 1/2/07, Ole Ersoy <ole_ersoy@...> wrote:
> > Hey David,
> >
> > I'm going to go over some obvious stuff, which you
> > already know, just for clearity.
> >
> > I tried to start with something really simple that
> > represents everything we do when coding, which is
> > mapping inputs to outputs and storing those inputs
> and
> > outputs in tighthy little slots on objects.
> >
> > So in that example we have two slots.
> >
> > Let me just define a slot as something that can
> > contain everything allowed/understood by a
> computer.
> >
> > Then we constrained the slots by making them int.
> >
> > Now they can only contain the subset of all values
> > allowed that are int.
> >
> > So now we apply an Operation to the slots and put
> the
> > result in a different slot.
> >
> > So we have a Class that with private int a,b,c
> > and
> >
> > an Operation defined in
> > Java
> >
> > public int multiply(int a, int b)
> > return aXb;
> >
> > It does not really matter what that Operation is,
> the
> > only thing we care about is that it correctly maps
> the
> > inputs to the outputs.
> >
> > So lets start with the inputs.
> >
> > They have already been constrained.
> >
> > But is it done or is it possible that we need to
> > constrain variable b further, to satisfy a API
> > contract definition.
> >
> > For instance b must be between 100 and 200.
> >
> > Quick side note(If an EMF model contained all the
> > variables, a, b, c, etc.) and we needed to place
> > constraints on a int datatype like this, we could
> use
> > an invarient constraint for that.
> >
> > OK - Back to the logic.
> >
> > So we constrain b further so that  100 < b < 200.
> >
> > So now we are wondering whether our method works?
> >
> > By looking at the constraint for a&b, being that
> "a"
> > is an int, and "b" is a further constrained int,
> >
> > and the mapping the method performs we know all
> the
> > possible return values.
> >
> > We also know all the possible input values.
> >
> > But we don't want to test every single input to
> > output...
> >
> > 101X1, 102X1, ...
> >
> > So which ones do we test?
> >
> > Let's start with the assuming that were always
> going
> > to pass legal values.
> >
> > So we want to test the type constraint on a and b,
> > being int.
> >
> > So lets just assume that on the platform we are
> > running legal values are
> >
> > -2222222222222222222 to 2222222222222222222
> >
> > So we use these two end of range values.
> >
> > And we test
> >
> > 101 and 199 for b, since that represents b's set
> of
> > edge points.
> >
> > So the combinations we want to test for any
> > mathematical operations with these two parameters
> are:
> >
> >  b              a
> > 101 X -2222222222222222222
> > 101 X 2222222222222222222
> > 199 X -2222222222222222222
> > 199 X 2222222222222222222
> >
> > If X works the way it's supposed to, then these
> tests
> > should pass.
> >
> > Also, we test
> >  b              a
> > 99  X -2222222222222222222
> > 99  X 2222222222222222222
> > 201 X -2222222222222222222
> > 201 X 2222222222222222222
> >
> > These should not pass.
> >
> > Then we assume that all other values are taken
> care
> > due to the definition of X.
> >
> > So were did we get the
> >
> >
>

> > values from.
> >
> > Lets think of a and b as being datatypes.
> >
> > b is just a new datatype that can only
> > have values between 100 and 200.
> >
> > So a DataType is just meta data defining an
> allowed
> > set of values...which is where EMF or Java
> reflection
> > comes in.  You would use them to analyze the meta
> data
> > defined for a type.  Then combine that with
> knowledge
> > of operators to generate test cases.
> >
> > Does that make more sense?
> >
> > Cheers,
> > - Ole
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > --- David Saff <saff@...> wrote:
> >
> > > Ole,
> > >
> > > I'm getting my head around your suggestions.
> (At
> > > least) one thing is
> > > tripping me up:
> > >
> > > On 12/31/06, Ole Ersoy <ole_ersoy@...>
> wrote:
> > > > "What does it mean for a method to be 100%
> unit
> > > > tested?"
> > > >
> > > > For instance suppose there's a method
> > > >
> > > > public int multiply(int a, int b)
> > > >
> > > > return aXb;
> > > >
> > > > Do we unit test this?
> > >
>