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From "Éric Daigneault" <>
Subject Re: multi-module unit testing
Date Tue, 02 Oct 2007 14:58:23 GMT
Hi Pierre,

It all depends on what you need to share.  I discovered that a lot of the
code I needed to share were things like data set loaders for specification
tests for example.  These are generic by nature and do not require any
dependencies, thus making isolation in a separate module pretty straight
forward.  However for mocks ans stubs François's solution is more elegant
where you will use the assembly plugin and generate an extra jar packaging
all the test stuff together.  all in all you will achieve the same end
result.  However you must be careful here on what you share between projects
as it is generally considered bad practice for unit tests to have
dependencies outside their domain.  This being said recoding the same stub
every time you need to fake a class from another jar is just insane,
packaging mocks for the classes at the interface of the package within the
same project and packaging them as separate test jars sounds much better.

This is where I was coming with the solution I proposed earlier, most of my
modules are split in two, one with all the interfaces, factories access and
such and will becomes the API, another for the implementation.  APIs can
have dependencies with other APIs, Implementation will only have
dependencies to it's API and other APIs.  The upside is that it forces me to
think long and hard about what has to be shared, what service provides the
library, and how it is to be done.  Natural corollary from this is that the
test code that needs to be shared is quite easy to determine as other
projects will have dependency only on the API.  This is how I get to prevent
circular dependencies since the tests will have the dame dependency graph as
the rest of the project.

Downside is that the project becomes very large very fast (3 to one split in
modules), and this is where François's proposal becomes interesting, Under
the same module project I could have it generate all three jars.  Sounds a
bit extreme but since I adopted this Dependencies management through
dictatorship I found my advil consumption dropped dramatically, especially
when the interns that work here are warned that some medival torture
apparatus was rigged to their chairs and wired to the build,  I then let
their imaginations connect the dots if the link with anything but API
packages.  <evil gin>

Anyhow, bit verbose but I hope it helped with your spinning head. ^_^.


Éric :D.

On 10/2/07, Awaragi <> wrote:
> Hi Eric,
> Thank you for your reply. Your solution is definitly getting me there but
> I
> am still a little bit confused about dependencies of these projects.
> Won't you run into a cirucular dependency issue between common test
> project
> and the library it support? From example, A, B are lib projects and C is
> app
> project, currently test setup classes are in A and B and are used by A and
> B
> test classes. So in theory, say you create a test project T, C will depend
> on A, B and T, T depends on A and B but A and B also depend on T. Maybe I
> am
> thinking too much? My head is definitly hurting %-|
> Thanks again,
> Pierre
> Eric Daigneault-2 wrote:
> >
> > Hi Pierre,
> >
> > The way I solved this for myself was to create a test project and put
> all
> > the common test code in it (as normal stuff, not as test stuff) then I
> > used
> > the test project in all other projects as a dependency.  This way I have
> > access to the common test stuff.  then to ensure that the extra project
> > (jar) does not make it in the final package I declared it as test in
> it`s
> > dependency scope.
> >
> > Extending the above principle I usually have two such jars for my
> > projects,
> > one that is all the common code used in all tests, there I place all the
> > generic stuff that can be reusable and is not specific.  Another  I will
> > put
> > all the mocks stubs and other such classes that are specific to the high
> > level project.  This way all modules will have access to them and I only
> > code my stuff once.  Great thing about this is that I can then code unit
> > tests on the test classes.  May sound a bit excessive but when people
> > lives
> > depend on the code you produce a bit of paranoia actually help to
> protect
> > ones sanity.
> >
> > Of course for the stubs parts, to prevent circular dependencies you may
> > have
> > to separate the interface for your library from the implementation,
> which
> > in
> > time makes for more stable code.  The downside is the multiplication of
> > modules.
> >
> > I hope this helps
> >
> > Éric :D.
> >
> >
> > On 10/1/07, Awaragi <> wrote:
> >>
> >>
> >> Hi All,
> >>
> >> i hope that this question was not asked before as I am new to maven and
> >> to
> >> this forum. I am trying to build a multi-module project with three
> >> modules:
> >> libraries A and B and application C which depends on A and B. Libraries
> A
> >> and B have their unit testing classes which use a setup class to load
> >> testing resources, setup database connection, etc. This works all fine
> >> and
> >> nice for A and B. Now I am in the process of writting unit tests for
> >> application module C and i don't want to do copy/paste of the setup
> >> classes
> >> of A and B but I cannot find a way to make unit test classes of C to
> >> depend
> >> on unit test classes of A and B.
> >>
> >> I thought of moving some of these setup classes to main as a workaround
> >> but
> >> then i have to add quite a few test libraries to these modules and to
> the
> >> web-inf/lib folder of the final war file. Including a database jdbc
> >> driver
> >> is not acceptable so this workaround is not the way to go.
> >>
> >> Can anyone please help me with this setup?
> >>
> >> Pierre
> >> --
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> >>
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> >
> >
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