Improved error messages for bindings

[BenjaminRodenberg]

Migrated precice/precice#547 here.

Closes #74, closes #7

[BenjaminRodenberg]

The implementation of the checks looks good. However, the checks are actually not used. I assume that the relevant code has been removed within a merge or similar?

[BenjaminRodenberg]

The implementation of the checks looks good. However, the checks are actually not used. I assume that the relevant code has been removed within a merge or similar?

precice/precice#547 contains the relevant parts. I will manually move them to this PR.

[BenjaminRodenberg]

I tried import precice from my home directory (note: not python-bindings) and got the following error:

>>> import precice
pTraceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "precice.pyx", line 12, in init precice
ModuleNotFoundError: No module named 'error_handling'

I assume that error_handling.py has to be added to the module properly, since otherwise it cannot be found. If you import precice from within python-bindings this is no problem, because error_handling.py is on the path.

I tried to run the examples from write_block_vector_data and ran into some more confusing error messages

[IshaanDesai]

Need to provide a good error message for: #74

[BenjaminRodenberg]

#74 gives an example how we can deal with certain kinds of errors and how we can also test that under certain conditions the correct kind of error is thrown.

[BenjaminRodenberg]

Some more things that we should check (not covered by #74):

• If we expect an id it should be an int
• If we expect ids it should be an array_like of ints
• If we expect a single value it should not be an array_like (non-block operations)

Probably there is much more, but this is what currently comes to my mind.

[IshaanDesai]

At the moment only the existing assertion statements have been made more descriptive. There is scope for adding further checks and this is up for discussion

[BenjaminRodenberg]

Generally helpful error messages. If you want, you can also provide the values that go into the assertion. I'm giving an example below. But this is optional.

[IshaanDesai]

Only the following test fails: https://github.com/precice/python-bindings/pull/9/checks?check_run_id=2176968006
Rest from my side this PR is ready to merge.

[BenjaminRodenberg]

Only the following test fails: https://github.com/precice/python-bindings/pull/9/checks?check_run_id=2176968006
Rest from my side this PR is ready to merge.

I think the failing test should have been fixed on develop already. Just merged via 1d76a09 and hope it's working now.