Raise exception in identify_stac_object for non-STAC objects

[duckontheweb]

Related Issue(s): #

• retrieving non-STAC entities via Links throws unintended error #340

Description:

• Fixes the logic in serialization.identify.identify_stac_object_type for all STAC object v0.8.* and above
  As per retrieving non-STAC entities via Links throws unintended error #340 and this comment, this was previously falling back to identifying JSON-like dicts as Catalogs if they did not meet the other criteria.

• serialization.identify.identify_stac_object_type now returns None if the dict is not a STAC object, and serialization.identify.identify_stac_object raises a STACTypeError in this case

• Removes all examples for STAC versions lower than 0.8.

• UPDATE 2021-06-04: Removes some logic in the EO extension migration and in serialization.migrate that was specific to pre-0.8 STAC versions, since this was causing a significant drop in test coverage.

PR Checklist:

• Code is formatted (run scripts/format)
• Tests pass (run scripts/test)
• This PR maintains or improves overall codebase code coverage.
• Changes are added to the CHANGELOG. See the docs for information about adding to the changelog.

[duckontheweb]

@philvarner The example from #343 now throws the following exception:

>>> from pystac import Catalog
>>> c = Catalog.from_file("https://earth-search.aws.element84.com/v0")
>>> list(c.get_stac_objects('service-desc'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jduckworth/Code/pystac/pystac/stac_object.py", line 297, in get_stac_objects
    link.resolve_stac_object(root=self.get_root())
  File "/Users/jduckworth/Code/pystac/pystac/link.py", line 213, in resolve_stac_object
    obj = stac_io.read_stac_object(target_href, root=root)
  File "/Users/jduckworth/Code/pystac/pystac/stac_io.py", line 139, in read_stac_object
    return self.stac_object_from_dict(d, href=href, root=root)
  File "/Users/jduckworth/Code/pystac/pystac/stac_io.py", line 96, in stac_object_from_dict
    result = pystac.serialization.stac_object_from_dict(d, href, root)
  File "/Users/jduckworth/Code/pystac/pystac/serialization/__init__.py", line 41, in stac_object_from_dict
    info = identify_stac_object(d)
  File "/Users/jduckworth/Code/pystac/pystac/serialization/identify.py", line 369, in identify_stac_object
    raise pystac.STACTypeError("JSON does not represent a STAC object.")
pystac.errors.STACTypeError: JSON does not represent a STAC object.

[codecov-commenter]

Codecov Report

Merging #402 (36303f6) into main (eb15669) will decrease coverage by 0.11%.
The diff coverage is 96.00%.

@@            Coverage Diff             @@
##             main     #402      +/-   ##
==========================================
- Coverage   89.67%   89.56%   -0.12%     
==========================================
  Files          39       39              
  Lines        5213     5115      -98     
==========================================
- Hits         4675     4581      -94     
+ Misses        538      534       -4     

Impacted Files	Coverage Δ
pystac/extensions/eo.py	96.60% <ø> (-0.36%)	⬇️
pystac/serialization/identify.py	89.61% <95.83%> (+1.42%)	⬆️
pystac/serialization/migrate.py	83.33% <100.00%> (-1.97%)	⬇️
pystac/validation/schema_uri_map.py	86.84% <0.00%> (-2.64%)	⬇️
pystac/serialization/common_properties.py	92.85% <0.00%> (-1.79%)	⬇️
pystac/validation/stac_validator.py	86.20% <0.00%> (-1.15%)	⬇️
pystac/collection.py	93.72% <0.00%> (-0.84%)	⬇️

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[lossyrob]

Nice work! This will avoid a lot of head-scratching debug time for users, and also simplifies the library a lot by getting rid of the pre-0.8 logic.