Start separating normalisation from validation logic

docs/changelog.rst

@@ -7,6 +7,18 @@ Changes in nbformat
 In Development
 ==============
 
+The  biggest change in nbformat 5.5.0 is the deprecation of arguments to
+``validate()`` that try to fix notebooks errors during validation.
+
+``validate()`` is a function that is core to the security model of Jupyter,
+and is assumed in a number of places to not mutate it's argument, or try to fix
+notebooks passed to it.
+
+Auto fixing of notebook in validate can also hide subtle bugs, and will
+therefore be updated in a near future to not take any of the argument related to
+auto-fixing, and fail instead of silently modifying its parameters on invalid
+notebooks.
+
 5.4.0
 =====
 * Add project URLs to ``setup.py``

nbformat/current.py

@@ -84,7 +84,7 @@ class NBFormatError(ValueError):
 
 def _warn_format():
     warnings.warn(
-        """Non-JSON file support in nbformat is deprecated.
+        """Non-JSON file support in nbformat is deprecated since nbformat 1.0.
     Use nbconvert to create files of other formats."""
     )
 
@@ -107,13 +107,21 @@ def parse_py(s, **kwargs):
 
 def reads_json(nbjson, **kwargs):
     """DEPRECATED, use reads"""
-    warnings.warn("reads_json is deprecated, use reads")
+    warnings.warn(
+        "reads_json is deprecated since nbformat 3.0, use reads",
+        DeprecationWarning,
+        stacklevel=2,
+    )
     return reads(nbjson)
 
 
 def writes_json(nb, **kwargs):
     """DEPRECATED, use writes"""
-    warnings.warn("writes_json is deprecated, use writes")
+    warnings.warn(
+        "writes_json is deprecated since nbformat 3.0, use writes",
+        DeprecationWarning,
+        stacklevel=2,
+    )
     return writes(nb, **kwargs)
 
 
@@ -158,7 +166,9 @@ def reads(s, format="DEPRECATED", version=current_nbformat, **kwargs):
     nb = reader_reads(s, **kwargs)
     nb = convert(nb, version)
     try:
-        validate(nb)
+        with warnings.catch_warnings():
+            warnings.filterwarnings("ignore", category=DeprecationWarning)
+            validate(nb, repair_duplicate_cell_ids=False)
     except ValidationError as e:
         get_logger().error("Notebook JSON is invalid: %s", e)
     return nb
@@ -186,7 +196,9 @@ def writes(nb, format="DEPRECATED", version=current_nbformat, **kwargs):
         _warn_format()
     nb = convert(nb, version)
     try:
-        validate(nb)
+        with warnings.catch_warnings():
+            warnings.filterwarnings("ignore", category=DeprecationWarning)
+            validate(nb, repair_duplicate_cell_ids=False)
     except ValidationError as e:
         get_logger().error("Notebook JSON is invalid: %s", e)
     return versions[version].writes_json(nb, **kwargs)

nbformat/json_compat.py

@@ -88,6 +88,8 @@ def _validator_for_name(validator_name):
     for (name, module, validator_cls) in _VALIDATOR_MAP:
         if module and validator_name == name:
             return validator_cls
+    # we always return something.
+    raise ValueError(f"Missing validator for {repr(validator_name)}")
 
 
 def get_current_validator():