UKCP projection fails to plot due to previous AttributeError

[sadielbartholomew]

As evidenced by the Example 31 of the new regression test suite:

======================================================================
ERROR: test_example_31 (__main__.ExamplesTest.test_example_31)
Test Example 31.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/slb93/git-repos/cf-plot/cfplot/test/test_examples.py", line 997, in test_example_31
    cfp.con(f, lines=False)
  File "/home/slb93/git-repos/cf-plot/cfplot/cfplot.py", line 4037, in con
    _plot_map_axes(
  File "/home/slb93/git-repos/cf-plot/cfplot/cfplot.py", line 2982, in _plot_map_axes
    if plotvars.proj == "UKCP" and plotvars.grid:
                                   ^^^^^^^^^^^^^
AttributeError: 'pvars' object has no attribute 'grid'

from the minimal reproducer code:

        f = cf.read(f"<path to 'cfplot_data' dir of data files for tests>/ukcp_rcm_test.nc")[0]
        cfp.mapset(proj="UKCP", resolution="50m")  # fails here with the above issue

Looks like a very quick fix to me, but I will wait to get the rest of the test issues diagnosed before putting in the fixes.

[sadielbartholomew]

OK for some reason, in interactive Python that line works fine, but when run as part of the test suite it fails with the above, so there is some cfp plotting variable setup which is required to re-create this one. I will investigate further once I know what is failing across the test suite.

[sadielbartholomew]

Update: I can recreate this locally, with the following calls from the example (note the previous cfp.con calls which work):

>>> f = cf.read("cfplot_data/ukcp_rcm_test.nc")[0]
>>> cfp.con(f, lines=False)
>>> cfp.setvars(grid_x_spacing=1, grid_y_spacing=1)
>>> cfp.con(f, lines=False)
>>> cfp.mapset(proj="UKCP", resolution="50m")
>>> cfp.con(f, lines=False)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/slb93/git-repos/cf-plot/cfplot/cfplot.py", line 4037, in con
    _plot_map_axes(
  File "/home/slb93/git-repos/cf-plot/cfplot/cfplot.py", line 2982, in _plot_map_axes
    if plotvars.proj == "UKCP" and plotvars.grid:
                                   ^^^^^^^^^^^^^
AttributeError: 'pvars' object has no attribute 'grid'