add new tests (load catalog and quantities)

[yymao]

and also switch to pytest

[wmwv]

Code looks fine.

I got two failed tests. If this is expected and the tests are revealing a problem, then adding the tests in the PR remains good.

If there is instead some reason that the test itself is wrong in its expectations, then please fix.

=================================== FAILURES ===================================
______ test_load_catalog_and_quantities[dc2_eimages_run1.2p_visit-181898] ______

catalog = 'dc2_eimages_run1.2p_visit-181898'

    @pytest.mark.parametrize('catalog', all_catalogs)
    def test_load_catalog_and_quantities(catalog):
>       cat = GCRCatalogs.load_catalog(catalog)

tests/test_catalogs.py:11:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
GCRCatalogs/register.py:171: in load_catalog
    return load_catalog_from_config_dict(config)
GCRCatalogs/register.py:120: in load_catalog_from_config_dict
    BaseGenericCatalog)(**catalog_config)
/opt/lsst/software/stack/python/miniconda3-4.5.4/envs/lsst-scipipe-fcd27eb/lib/python3.6/site-packages/GCR/base.py:27: in __init__
    self._subclass_init(**kwargs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <GCRCatalogs.eimage.EImageReader object at 0x2aaac852b240>
root_dir = '/global/projecta/projectdirs/lsst/global/DC2/DC2-R1-2p-WFD-r/000008'
visits = 181898, default_rebinning = 16, dirpath_contain = None
filename_pattern = 'lsst_e_(\\d+)(?:_f\\d+)?_(R\\d\\d)_(S\\d\\d)(?:_E\\d+)?(?:_[a-z])?\\.fits\\.gz$'
kwargs = {'description': 'phoSim e-images for Run 1.2p (visit 181898)', 'subclass_name': 'eimage.EImageReader'}

    def _subclass_init(self, root_dir, visits=None, default_rebinning=None,
                       dirpath_contain=None, filename_pattern=_FILENAME_PATTERN,
                       **kwargs):
        # pylint: disable=W0221
        if not os.path.isdir(root_dir):
>           raise ValueError('`root_dir` must be a valid directory')
E           ValueError: `root_dir` must be a valid directory

GCRCatalogs/eimage.py:101: ValueError
______ test_load_catalog_and_quantities[dc2_eimages_run1.2i_visit-181898] ______

catalog = 'dc2_eimages_run1.2i_visit-181898'

    @pytest.mark.parametrize('catalog', all_catalogs)
    def test_load_catalog_and_quantities(catalog):
>       cat = GCRCatalogs.load_catalog(catalog)

tests/test_catalogs.py:11:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
GCRCatalogs/register.py:171: in load_catalog
    return load_catalog_from_config_dict(config)
GCRCatalogs/register.py:120: in load_catalog_from_config_dict
    BaseGenericCatalog)(**catalog_config)
/opt/lsst/software/stack/python/miniconda3-4.5.4/envs/lsst-scipipe-fcd27eb/lib/python3.6/site-packages/GCR/base.py:27: in __init__
    self._subclass_init(**kwargs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <GCRCatalogs.eimage.EImageReader object at 0x2aab1f8c46a0>
root_dir = '/global/projecta/projectdirs/lsst/production/DC2_ImSim/DC2-R1-2p-WFD-r'
visits = 181898, default_rebinning = 16, dirpath_contain = '000008_batch'
filename_pattern = 'lsst_e_(\\d+)(?:_f\\d+)?_(R\\d\\d)_(S\\d\\d)(?:_E\\d+)?(?:_[a-z])?\\.fits\\.gz$'
kwargs = {'description': 'ImSim e-images for Run 1.2i (visit 181898)', 'subclass_name': 'eimage.EImageReader'}

    def _subclass_init(self, root_dir, visits=None, default_rebinning=None,
                       dirpath_contain=None, filename_pattern=_FILENAME_PATTERN,
                       **kwargs):
        # pylint: disable=W0221
        if not os.path.isdir(root_dir):
>           raise ValueError('`root_dir` must be a valid directory')
E           ValueError: `root_dir` must be a valid directory

GCRCatalogs/eimage.py:101: ValueError

[wmwv]

Yay! We're living in the future!

[yymao]

🎉

[yymao]

@wmwv thanks, the errors you saw have been fixed in #318 (and merged to master) but not yet merged to this branch.

I'm going to merge this.