Re: [Cobertura-devel] Is loading and saving before each unit test expensive?

[Steve C. <sch...@gm...>]

That's because you have forkedmode set to default in your junit arguments.
The method you are currently doing is a very expensive method for junit
testing.

Here's how junit (default) with cobertura works. Say we have 10 unit tests
(test1-test10). When the jvm first starts it immediately creates a map for
cobertura and begins to take note of all the line numbers and other items
for keeping track of instrumented code(magic). When the jvm shuts down
cobertura has a "release" task where it writes code to the .ser file. This
is where you see the Loaded information on 816 classes. It will then save
the infrormation to the file and be complete. Now here's where the
inefficient part comes in. The default junit ant target has something
called fork which essentially means "Create a new JVM for every single unit
test". That means for test1 though test10 you will see about 10 jvms
started up and shut down. so you will see all the loaded and saved
information constantly.

There are good and bad reasons for this:
Good:
No leaking data - Static (non-final) variables are not an issue.
No issues with legacy code. Legacy code can have no failures.
Bad:
Incredibly slow (I've seen unit tests take 2+ hours vs 30 minutes with this
option).
Proof of bad junit (junits should never contain leaking data, or need to
clean up properly in tearDown methods).

The only way you can fix this issue is to set forkmode="once" as part of
your ant target. Again this COULD cause junits to fail, however it will
increase the speed of the junits by a lot. See the documentation on
forkmode: http://ant.apache.org/manual/Tasks/junit.html


On Tue, Nov 13, 2012 at 2:47 PM, KARR, DAVID <dk...@at...> wrote:

> As Cobertura is excessively verbose right now, I notice that before every
> unit test class is run, I see the following:
> ----------------
> Cobertura: Loaded information on 816 classes.
> Cobertura: Saved information on 816 classes.
> ----------------
>
> Obviously, the number of classes loaded and saved will vary, but it really
> is doing this before very single unit test class, even when all of them
> were spawned from the same "junit" task.  I first wonder if it's expensive
> to do this, and second I would wonder whether it's reasonable or possible
> to do this load and save at a higher scope, like only once for each "junit"
> task invocation.
>
>
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