Exceptions

---

title: Exceptions

When python code snippets raise exceptions, those can be expected by the code or unexpected.

If unexpected they will raise an exception.

from hitchrunpy import ExamplePythonCode
from ensure import Ensure
import hitchbuildpy
import hitchbuild

BUILD_DIR = "/path/to/build_dir/.."

virtualenv = hitchbuildpy.VirtualenvBuild(
    "/path/to/build_dir/../py3.7",
    base_python=hitchbuildpy.PyenvBuild(
        '/path/to/share_dir/../pyenv3.7',
        "3.7",
    ),
)

virtualenv.verify()

pyrunner = ExamplePythonCode(
    virtualenv.bin.python,
    '/path/to/working_dir',
)

Occurs as expected:

result = pyrunner.with_code("""

class CustomException(Exception):
    pass

raise CustomException('This should hâppen')

""").expect_exceptions().run()

result.exception_was_raised("__main__.CustomException")

assert result.exception.message == "This should hâppen"
assert result.exception.exception_type == "__main__.CustomException"

Different to expected exception:

result = pyrunner.with_code("""

class AnotherCustomException(Exception):
    pass

raise AnotherCustomException('This should happen')

""").expect_exceptions().run()

result.exception_was_raised("__main__.CustomException")

hitchrunpy.exceptions.ExpectedExceptionWasDifferent:
Expected exception '__main__.CustomException', instead '__main__.AnotherCustomException' was raised:

[0]: function '[[ BRIGHT ]]<module>[[ RESET ALL ]]'
  /path/to/working/examplepythoncode.py


        67 :
        68 :
    --> [[ BRIGHT ]]69[[ RESET ALL ]] :     run_example_code()
        70 : except Exception as error:



[1]: function '[[ BRIGHT ]]run_example_code[[ RESET ALL ]]'
  /path/to/working/examplepythoncode.py


        63 :
        64 :
    --> [[ BRIGHT ]]65[[ RESET ALL ]] :         runcode()
        66 :



[2]: function '[[ BRIGHT ]]runcode[[ RESET ALL ]]'
  /path/to/working/examplepythoncode.py


        58 :                             pass
        59 :
    --> [[ BRIGHT ]]60[[ RESET ALL ]] :                         raise AnotherCustomException('This should happen')
        61 :



[[ RED ]][[ BRIGHT ]]__main__.AnotherCustomException[[ RESET ALL ]]
  [[ DIM ]][[ RED ]]None[[ RESET ALL ]]
[[ RED ]]This should happen[[ RESET FORE ]]

Expect any kind of exception:

result = pyrunner.with_code("""

raise Exception(u"ân exception")

""").expect_exceptions().run()

result.exception_was_raised()

No exception occurs when expected:

result = pyrunner.with_code("pass").expect_exceptions().run()

result.exception_was_raised("__main__.CustomException")

hitchrunpy.exceptions.ExpectedExceptionButNoExceptionOccurred:
Expected exception '__main__.CustomException', but no exception occurred.

Expected raised but with different message:

result = pyrunner.with_code("""

class CustomException(Exception):
    pass

raise CustomException('This was not\\nthe expected messâge.')

""").expect_exceptions().run()

result.exception_was_raised("__main__.CustomException", 'This was\nthe expected messâge')

hitchrunpy.exceptions.ExpectedExceptionMessageWasDifferent:
Expected exception '__main__.CustomException' was raised, but message was different.

ACTUAL:
This was not
the expected messâge.

EXPECTED:
This was
the expected messâge
DIFF:
- This was not
?         ----
+ This was
- the expected messâge.?                     -
+ the expected messâge

Executable specification

Documentation automatically generated from exception.story storytests.