Let format_index handle the container too.

May as well, this is only used in 2 places.

Author: Julian

jsonschema/_utils.py

@@ -71,22 +71,26 @@ def load_vocabulary(name):
     return vocabulary
 
 
-def format_as_index(indices):
+def format_as_index(container, indices):
     """
     Construct a single string containing indexing operations for the indices.
 
-    For example, [1, 2, "foo"] -> [1][2]["foo"]
+    For example for a container ``bar``, [1, 2, "foo"] -> bar[1][2]["foo"]
 
     Arguments:
 
+        container (str):
+
+            A word to use for the thing being indexed
+
         indices (sequence):
 
             The indices to format.
     """
 
     if not indices:
-        return ""
-    return f"[{']['.join(repr(index) for index in indices)}]"
+        return container
+    return f"{container}[{']['.join(repr(index) for index in indices)}]"
 
 
 def find_additional_properties(instance, schema):

jsonschema/exceptions.py

@@ -66,22 +66,24 @@ def __str__(self):
         if any(m is _unset for m in essential_for_verbose):
             return self.message
 
-        schema_word = self._word_for_schema_in_error_message
         schema_path = _utils.format_as_index(
-            list(self.relative_schema_path)[:-1],
+            container=self._word_for_schema_in_error_message,
+            indices=list(self.relative_schema_path)[:-1],
+        )
+        instance_path = _utils.format_as_index(
+            container=self._word_for_instance_in_error_message,
+            indices=self.relative_path,
         )
-        instance_word = self._word_for_instance_in_error_message
-        instance_path = _utils.format_as_index(self.relative_path)
         prefix = 16 * " "
 
         return dedent(
             f"""\
             {self.message}
 
-            Failed validating {self.validator!r} in {schema_word}{schema_path}:
+            Failed validating {self.validator!r} in {schema_path}:
                 {indent(pformat(self.schema, width=72), prefix).lstrip()}
 
-            On {instance_word}{instance_path}:
+            On {instance_path}:
                 {indent(pformat(self.instance, width=72), prefix).lstrip()}
             """.rstrip(),
         )