feat: adds api.get_taxonomy

for completeness.

Author: pomegranited

openedx_tagging/core/tagging/api.py

@@ -10,7 +10,7 @@
 Please look at the models.py file for more information about the kinds of data
 are stored in this app.
 """
-from typing import Generator, List, Type
+from typing import Generator, List, Type, Union
 
 from django.db.models import QuerySet
 from django.utils.translation import gettext_lazy as _
@@ -44,6 +44,12 @@ def create_taxonomy(
     return taxonomy
 
 
+def get_taxonomy(id: int) -> Union[Taxonomy, None]:
+    """
+    Returns a Taxonomy of the appropriate subclass which has the given ID.
+    """
+    return Taxonomy.objects.filter(id=id).first()
+
 def get_taxonomies(enabled=True) -> QuerySet:
     """
     Returns a queryset containing the enabled taxonomies, sorted by name.

tests/openedx_tagging/core/tagging/test_api.py

@@ -38,6 +38,12 @@ def test_create_taxonomy_bad_object_tag_class(self):
             exc.exception
         )
 
+    def test_get_taxonomy(self):
+        tax1 = tagging_api.get_taxonomy(1)
+        assert tax1 == self.taxonomy
+        no_tax = tagging_api.get_taxonomy(10)
+        assert no_tax is None
+
     def test_get_taxonomies(self):
         tax1 = tagging_api.create_taxonomy("Enabled")
         tax2 = tagging_api.create_taxonomy("Disabled", enabled=False)