fix: Remove os-dependent pieces of schema validation

src/pyhf/schema/loader.py

@@ -19,7 +19,7 @@ def load_schema(schema_id: str):
     Args:
         schema_id (str): Relative path to schema from :attr:`pyhf.schema.path`
 
-    Example:
+    Examples:
         >>> import pyhf
         >>> schema = pyhf.schema.load_schema("1.0.0/defs.json")
         >>> type(schema)
@@ -31,6 +31,18 @@ def load_schema(schema_id: str):
             ...
         pyhf.exceptions.SchemaNotFound: ...
 
+        >>> import pyhf
+        >>> import os
+        >>> schema = pyhf.schema.load_schema(f"1.0.0{os.sep}defs.json")
+        >>> type(schema)
+        <class 'dict'>
+        >>> schema.keys()
+        dict_keys(['$schema', '$id', 'definitions'])
+        >>> pyhf.schema.load_schema(f"0.0.0{os.sep}defs.json")  # doctest: +ELLIPSIS
+        Traceback (most recent call last):
+            ...
+        pyhf.exceptions.SchemaNotFound: ...
+
     Returns:
         schema (dict): The loaded schema.
 

src/pyhf/schema/validator.py

@@ -1,4 +1,6 @@
 import numbers
+import os
+from pathlib import Path
 from typing import Mapping, Union
 
 import jsonschema
@@ -70,12 +72,15 @@ def validate(
 
     version = version or variables.SCHEMA_VERSION
 
-    schema = load_schema(f'{version}/{schema_name}')
+    schema = load_schema(str(Path(version).joinpath(schema_name)))
 
-    # note: trailing slash needed for RefResolver to resolve correctly
+    # note: trailing slash needed for RefResolver to resolve correctly and by
+    # design, pathlib strips trailing slashes. See ref below:
+    # * https://bugs.python.org/issue21039
+    # * https://github.com/python/cpython/issues/65238
     resolver = jsonschema.RefResolver(
-        base_uri=f"file://{variables.schemas}/{version}/",
-        referrer=f"{schema_name}",
+        base_uri=f"{Path(variables.schemas).joinpath(version).as_uri()}{os.sep}",
+        referrer=schema_name,
         store=variables.SCHEMA_CACHE,
     )