Fixes to read VII testdata

[ninahakansson]

Modifications needed to read VII testdata generated 20200921212800.

• Closes VIIl1b reader fails for testdata #1460
• Tests added
• Passes flake8 satpy

[codecov]

Codecov Report

Merging #1462 (7d82089) into master (a18b6e2) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1462      +/-   ##
==========================================
+ Coverage   90.52%   90.58%   +0.05%     
==========================================
  Files         238      239       +1     
  Lines       34153    34314     +161     
==========================================
+ Hits        30916    31082     +166     
+ Misses       3237     3232       -5     

Flag	Coverage Δ
behaviourtests	4.53% <0.00%> (+<0.01%)	⬆️
unittests	91.06% <100.00%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
satpy/readers/vii_base_nc.py	94.17% <100.00%> (ø)
satpy/readers/vii_l1b_nc.py	96.15% <100.00%> (+0.07%)	⬆️
satpy/tests/reader_tests/test_vii_l1b_nc.py	100.00% <100.00%> (ø)
satpy/tests/test_file_handlers.py	100.00% <0.00%> (ø)
satpy/tests/reader_tests/test_abi_l1b.py	100.00% <0.00%> (ø)
satpy/tests/reader_tests/test_olci_nc.py	100.00% <0.00%> (ø)
satpy/_compat.py	100.00% <0.00%> (ø)
satpy/tests/test_readers.py	99.19% <0.00%> (+0.14%)	⬆️
satpy/readers/__init__.py	97.45% <0.00%> (+0.35%)	⬆️
satpy/readers/file_handlers.py	97.18% <0.00%> (+1.23%)	⬆️
... and 2 more

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[mraspaud]

This looks good to me, just have a minor inline comment.

Just for my understanding, is this supposed to be backward compatible with older versions of the test dataset?

[mraspaud]

Suggested change

	if dataset_info.get('calibration', None) is not None:
	if dataset_info.get('calibration') is not None:

None is already the default return value for get.
Also, should we issue a warning here if no calibration info is found?

[ninahakansson]

Already in the vii_l1b_nc.yaml we expect some datasets to not have calibration for example "observation_azimuth".

[ninahakansson]

@mraspaud I did not try to make it compatible with old versions of testdata. I think the actual data is still the same and only the format is improved.

[mraspaud]

OK, in this case should we also discard the old file pattern?

[ninahakansson]

I do not know, it might be an older version but could also be the correct pattern but someone else making the files.

[sjoro]

LGTM

[ninahakansson]

@mraspaud @sjoro I forgot to fix the brightness temperatures. Added that now.