libdoc error when using BuiltIn().get_library_instance() in constructor

[vbs]

Hi Guys,

I just discovered the amazing libdoc to generate keyword documentation for my test libraries. Sadly it turned out that libdoc throws an error when a library is using BuiltIn().get_library_instance in its constructor. Here a simplified test library to reproduce the problem:

from robot.libraries.BuiltIn import BuiltIn

class ScDocTestLibrary():

    def __init__(self):

        sc = BuiltIn().get_library_instance("ScConnector")

        self.inputDirectory = sc.getInputDir()

Gives me:

X:\robot-framework-test\testlibs\doc>python -m robot.libdoc ..\ScDocTestLibrary.py scdotest.html

Initializing test library 'ScDocTestLibrary' with no arguments failed: RobotNotRunningError: Cannot access execution context

Traceback (most recent call last):

  File "X:\robot-framework-test\testlibs\ScDocTestLibrary.py", line 11, in __init__

    sc = BuiltIn().get_library_instance("ScConnector")

  File "C:\Python27\lib\site-packages\robot\libraries\BuiltIn.py", line 2964, in get_library_instance

    return self._namespace.get_library_instance(name)

  File "C:\Python27\lib\site-packages\robot\libraries\BuiltIn.py", line 75, in _namespace

    return self._get_context().namespace

  File "C:\Python27\lib\site-packages\robot\libraries\BuiltIn.py", line 70, in _get_context

    raise RobotNotRunningError('Cannot access execution context')

Try --help for usage information.

X:\robot-framework-test\testlibs\doc>

I guess libdoc actually is trying to instantiate this class and fails cause "ScConnectorLibrary" is not loaded.

Is there anything I can do about it?

Thanks alot!

Robin

[Bryan Oakley]

I avoid this by using properties for things that depend on a runtime context. For example:

    from robot.libraries.BuiltIn import BuiltIn

    class ScDocTestLibrary():
        @property
        def inputDirectory(self):

            sc = BuiltIn().get_library_instance("ScConnector")

            return sc.getInputDir()

With the above, the code doesn't actually call get_library_instance until the first time something needs self.inputDirectory.

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[vbs]

Thanks for quick answer! I can think I can use that pattern for most my libraries. I'm afraid there will be some places where I cannot apply it that way since the constructors are a bit more complex. I am a bit undecided if I want to change the structure of those libraries "just" to make libdoc work though (for example by introducing another "init" function or something that has to be invoked manually to properly initialize the library object).

Another question (a bit offtopic): I noticed that libraries having constructor arguments do generally not work with libdoc. libdoc tries to instantiate the classes without constructor arguments and fails if arguments are existing. Is there also some workaround for it?

Thanks again & Cheers

Robin

[Tatu Aalto]

Ugh

I usually try to have a meaningful default value. If meaningful value cannot be guaranteed, I tend to use Python None and raise an meaningful exception when keyword is used. The other option is give the arguments from command line[1], the examples are at the end of the chapter 5.1.

[1] http://robotframework.org/robotframework/latest/RobotFrameworkUserGuide.html#general-usage

--

[Tatu Aalto]

Ugh

I have also always tough that code in below solves the problems with libdoc. But I did stumble on on problems when using hybrid library[1] and having that property. My libdoc command looks like this: python -m robot.libdoc --pythonpath . tmp.MyClassName list

If my code looks like this and is in tmp.py file:

from robot.libraries.BuiltIn import BuiltIn

from robot.api.deco import keyword

class MyClassName(object):

    def get_keyword_names(self):

        return [name for name in dir(self) if hasattr(getattr(self, name), 'robot_name')]

    @keyword

    def keyword_here(self):

        print self.get_lib

    @property

    def get_lib(self):

        return BuiltIn().get_library_instance('Selenium2Library')

Libdoc will fail on the following error: Calling dynamic method 'get_keyword_names' failed: RobotNotRunningError: Cannot access execution context

Now if my code looks like this:

from robot.libraries.BuiltIn import BuiltIn

class MyClassName(object):

    def get_keyword_names(self):

        return ['keyword_here']

    def keyword_here(self):

        print self.get_lib

    @property

    def get_lib(self):

        return BuiltIn().get_library_instance('Selenium2Library')

Libdoc works nicely. Is this a by intention or a bug somewhere?

-Tatu

[1] http://robotframework.org/robotframework/latest/RobotFrameworkUserGuide.html#hybrid-library-api

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[Pekka Klärck]

2016-03-17 17:44 GMT+02:00 Tatu Aalto <aalto...@gmail.com>:
>
> I have also always tough that code in below solves the problems with libdoc.
> But I did stumble on on problems when using hybrid library[1] and having
> that property. My libdoc command looks like this: python -m robot.libdoc
> --pythonpath . tmp.MyClassName list
>
> If my code looks like this and is in tmp.py file:
> from robot.libraries.BuiltIn import BuiltIn
> from robot.api.deco import keyword
>
>
> class MyClassName(object):
>
> def get_keyword_names(self):
> return [name for name in dir(self) if hasattr(getattr(self, name),
> 'robot_name')]
>
> @keyword
> def keyword_here(self):
> print self.get_lib
>
> @property
> def get_lib(self):
> return BuiltIn().get_library_instance('Selenium2Library')
>
> Libdoc will fail on the following error: Calling dynamic method
> 'get_keyword_names' failed: RobotNotRunningError: Cannot access execution
> context

The reason for the error is twofold:

- Robot needs to call your get_keyword_names method to know what
keywords the library implements.
- Your get_keyword_names indirectly executes get_lib property.

I don't think there's anything that could be changed on Robot side to
fix this issue. Possible solutions in your library include
blacklisting propertys and accessing attributes via class, not
instance, to avoid propertys being called.

Cheers,
.peke
--
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