On Wed, Jan 05, 2011 at 05:45:26PM +0200, Michael Goldish wrote:
> In complex tests (KVM) an exception string is often not informative enough and
> the traceback and source code have to be examined in order to figure out what
> caused the exception. Context strings are a way for tests to provide
> information about what they're doing, so that when an exception is raised, this
> information will be embedded in the exception string. The result is a concise
> yet highly informative exception string, which should make it very easy to
> figure out where/when the exception was raised.
>
> A typical example for a test where this may be useful is KVM's reboot test.
> Some exceptions can be raised either before or after the VM is rebooted (e.g.
> logging into the guest can fail) and whether they are raised before or after
> is critical to the understanding of the failure. Normally the traceback would
> have to be examined, but the proposed method makes it easy to know where the
> exception is raised without doing so. To achieve this, the reboot test should
> place calls to error.context() as follows:
>
> error.context("before reboot")
> <carry out pre-reboot actions>
> error.context("sending reboot command")
> <send the reboot command>
> error.context("after reboot")
> <carry out post-reboot actions>
>
> If login fails in the pre-reboot section, the resulting exception string can
> can have something like "context: before reboot" embedded in it. (The actual
> embedding is done in the next patch in the series.)
>
> Signed-off-by: Michael Goldish <mgoldish@xxxxxxxxxx>
> Signed-off-by: Eduardo Habkost <ehabkost@xxxxxxxxxx>
> ---
> client/common_lib/error.py | 97 +++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 95 insertions(+), 2 deletions(-)
>
Where's the automated test code? ;)
> +# def a():
> +# error.context("hello")
> +# b()
> +# error.context("world")
> +# get_context() ----> 'world'
> +#
> +# def b():
> +# error.context("foo")
> +# c()
> +#
> +# def c():
> +# error.context("bar")
> +# get_context() ----> 'hello --> foo --> bar'
The example above is outdated, isn't? It doesn't have the @context_aware
decorator.
--
Eduardo
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