Fix ModuleNotFoundError error when IPython is not installed

[seisman]

Description of proposed changes

Fixes#1241.

A test is needed but currently I have no idea how to test it.

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If adding new functionality, add an example to docstrings or tutorials.

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[weiji14]

A test is needed but currently I have no idea how to test it.

Maybe follow the style of 329e480 to only install IPython on the Python3.9/NumPy1.20 tests, but not on the Python 3.7/NumPy1.17 tests?

[seisman]

A test is needed but currently I have no idea how to test it.

Maybe follow the style of 329e480 to only install IPython on the Python3.9/NumPy1.20 tests, but not on the Python 3.7/NumPy1.17 tests?

Good suggestion. Done in db36410 using the ${{ matrix.optional-packages }} variable.

[weiji14]

I can't see any reporting on Codecov (because the codecov upload doesn't work with test failures due to #1217), but I'm assuming this line has code coverage?

[weiji14]

Ok, when IPython isn't installed, there are a few failures on the Python 3.7/NumPy 1.17 tests:

• test_figure_show at https://github.com/GenericMappingTools/pygmt/pull/1247/checks?check_run_id=2452429190#step:11:477
• pygmt.src.inset.inset doctest https://github.com/GenericMappingTools/pygmt/pull/1247/checks?check_run_id=2452429190#step:11:465
• test_pygmtscraperhttps://github.com/GenericMappingTools/pygmt/pull/1247/checks?check_run_id=2452429190#step:11:600

We can either do 1) Use something like pytest.importorskip or 2) Catch the pygmt.exceptions.GMTError for these tests

[seisman]

Ok, when IPython isn't installed, there are a few failures on the Python 3.7/NumPy 1.17 tests:

• test_figure_show at #1247 (checks)
• pygmt.src.inset.inset doctest #1247 (checks)
• test_pygmtscraper#1247 (checks)

We can either do 1) Use something like pytest.importorskip or 2) Catch the pygmt.exceptions.GMTError for these tests

Neither is good for the inset test, which is added in the docstring as an example.

[seisman]

As mentioned in #1247 (comment), I'm not happy with either way. Currently, I prefer to only commit the fix (79f329b) and don't try to work on the test/coverage, so that people can still use PyGMT even IPython is not installed (Fix #1241).

[weiji14]

As mentioned in #1247 (comment), I'm not happy with either way. Currently, I prefer to only commit the fix (79f329b) and don't try to work on the test/coverage, so that people can still use PyGMT even IPython is not installed (Fix #1241).

Yep, sounds ok with me.