feat: validate configuration of JSON files

docs/config_files.rst

@@ -44,8 +44,10 @@ JSON files
 
 Checker for any JSON file.
 
-First, configure the list of files to be checked in the :ref:`[nitpick.JsonFile] section <nitpick-jsonfile>`.
+First, configure the list of files to be checked in the :ref:`[nitpick.JSONFile] section <nitpick-jsonfile>`.
 
 Then add the configuration for the file name you just declared.
-
 Example: :ref:`the default config for package.json <default-package-json>`.
+
+If a JSON file is configured on ``[nitpick.JSONFile] file_names``, then a configuration for it should exist.
+Otherwise, a style validation error will be raised.

docs/defaults.rst

@@ -185,7 +185,7 @@ Content of `styles/package-json.toml <https://raw.githubusercontent.com/andreoli
 
 .. code-block:: toml
 
-    [nitpick.JsonFile]
+    [nitpick.JSONFile]
     file_names = ["package.json"]
 
     ["package.json"]

docs/generate_rst.py

@@ -17,7 +17,7 @@
 from nitpick import __version__
 from nitpick.constants import RAW_GITHUB_CONTENT_BASE_URL
 from nitpick.files.base import BaseFile
-from nitpick.files.json import JsonFile
+from nitpick.files.json import JSONFile
 from nitpick.files.pre_commit import PreCommitFile
 from nitpick.files.pyproject_toml import PyProjectTomlFile
 from nitpick.files.setup_cfg import SetupCfgFile
@@ -46,7 +46,7 @@
         "python37.toml": "Python 3.7",
     }
 )
-file_classes = [PyProjectTomlFile, SetupCfgFile, PreCommitFile, JsonFile]
+file_classes = [PyProjectTomlFile, SetupCfgFile, PreCommitFile, JSONFile]
 
 divider = ".. auto-generated-from-here"
 docs_dir = Path(__file__).parent.absolute()  # type: Path

docs/nitpick_section.rst

@@ -76,8 +76,8 @@ If a key/value pair appears in more than one sub-style, it will be overridden; t
 
 .. _nitpick-jsonfile:
 
-[nitpick.JsonFile]
+[nitpick.JSONFile]
 ------------------
 
-Configure the list of filenames that should be checked by the :py:class:`nitpick.files.json.JsonFile` class.
+Configure the list of filenames that should be checked by the :py:class:`nitpick.files.json.JSONFile` class.
 See :ref:`the default package.json style <default-package-json>` for an example of usage.

docs/source/nitpick.fields.rst

@@ -0,0 +1,7 @@
+nitpick.fields module
+=====================
+
+.. automodule:: nitpick.fields
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/nitpick.rst

@@ -22,11 +22,11 @@ Submodules
    nitpick.config
    nitpick.constants
    nitpick.exceptions
+   nitpick.fields
    nitpick.formats
    nitpick.generic
    nitpick.mixin
    nitpick.plugin
    nitpick.schemas
    nitpick.style
    nitpick.typedefs
-   nitpick.validators

src/nitpick/fields.py

@@ -0,0 +1,73 @@
+"""Custom Marshmallow fields and validators."""
+import json
+
+from marshmallow import ValidationError, fields
+from marshmallow.fields import Dict, Field, List, Nested, String
+from marshmallow.validate import Length
+
+from nitpick.generic import pretty_exception
+
+__all__ = ("Dict", "List", "String", "Nested", "Field")
+
+
+def is_valid_json(json_string: str) -> bool:
+    """Validate the string as JSON."""
+    try:
+        json.loads(json_string)
+    except json.JSONDecodeError as err:
+        raise ValidationError(pretty_exception(err, "Invalid JSON"))
+    return True
+
+
+class TrimmedLength(Length):  # pylint: disable=too-few-public-methods
+    """Trim the string before validating the length."""
+
+    def __call__(self, value):
+        """Validate the trimmed string."""
+        return super().__call__(value.strip())
+
+
+class FilledString(fields.String):
+    """A string field that must not be empty even after trimmed."""
+
+    def __init__(self, **kwargs):
+        super().__init__(validate=TrimmedLength(min=1), **kwargs)
+
+
+class JSONString(fields.String):
+    """A string field with valid JSON content."""
+
+    def __init__(self, **kwargs):
+        validate = kwargs.pop("validate", [])
+        validate.append(is_valid_json)
+        super().__init__(validate=validate, **kwargs)
+
+
+def string_or_list_field(object_dict, parent_object_dict):  # pylint: disable=unused-argument
+    """Detect if the field is a string or a list."""
+    if isinstance(object_dict, list):
+        return fields.List(FilledString(required=True, allow_none=False))
+    return FilledString()
+
+
+def validate_section_dot_field(section_field: str) -> bool:
+    """Validate if the combinatio section/field has a dot separating them."""
+    # FIXME: add tests for these situations
+    common = "Use this format: section_name.field_name"
+    if "." not in section_field:
+        raise ValidationError("Dot is missing. {}".format(common))
+    parts = section_field.split(".")
+    if len(parts) > 2:
+        raise ValidationError("There's more than one dot. {}".format(common))
+    if not parts[0].strip():
+        raise ValidationError("Empty section name. {}".format(common))
+    if not parts[1].strip():
+        raise ValidationError("Empty field name. {}".format(common))
+    return True
+
+
+def boolean_or_dict_field(object_dict, parent_object_dict):  # pylint: disable=unused-argument
+    """Detect if the field is a boolean or a dict."""
+    if isinstance(object_dict, dict):
+        return fields.Dict
+    return fields.Bool

src/nitpick/files/base.py

@@ -1,9 +1,10 @@
 """Base class for file checkers."""
 import abc
 from pathlib import Path
-from typing import Generator, List, Set, Type
+from typing import Generator, List, Optional, Set, Type
 
 import jmespath
+from marshmallow import Schema
 
 from nitpick import Nitpick
 from nitpick.formats import TomlFormat
@@ -24,6 +25,13 @@ class BaseFile(NitpickMixin, metaclass=abc.ABCMeta):
     file_dict = {}  # type: JsonDict
     nitpick_file_dict = {}  # type: JsonDict
 
+    #: Nested validation field for this file, to be applied in runtime when the validation schema is rebuilt.
+    #: Useful when you have a strict configuration for a file type (e.g. :py:class:`nitpick.files.json.JSONFile`).
+    nested_field = None  # type: Optional[Schema]
+
+    #: ``kwargs`` to be passes to the nested Marshmallow field above.
+    nested_field_kwargs = {}  # type: JsonDict
+
     fixed_name_classes = set()  # type: Set[Type[BaseFile]]
     dynamic_name_classes = set()  # type: Set[Type[BaseFile]]
 

src/nitpick/files/json.py

@@ -1,30 +1,45 @@
 """JSON files."""
 import json
+import logging
 
 from sortedcontainers import SortedDict
 
+from nitpick import fields
 from nitpick.files.base import BaseFile
 from nitpick.formats import JsonFormat
 from nitpick.generic import flatten, unflatten
+from nitpick.schemas import BaseNitpickSchema
 from nitpick.typedefs import JsonDict, YieldFlake8Error
 
 KEY_CONTAINS_KEYS = "contains_keys"
 KEY_CONTAINS_JSON = "contains_json"
+LOGGER = logging.getLogger(__name__)
 
 
-class JsonFile(BaseFile):
+class JSONFileSchema(BaseNitpickSchema):
+    """Validation schema for any JSON file added to the style."""
+
+    contains_keys = fields.List(fields.FilledString)
+    contains_json = fields.Dict(fields.FilledString, fields.JSONString)
+
+
+class JSONFile(BaseFile):
     """Checker for any JSON file.
 
-    First, configure the list of files to be checked in the :ref:`[nitpick.JsonFile] section <nitpick-jsonfile>`.
+    First, configure the list of files to be checked in the :ref:`[nitpick.JSONFile] section <nitpick-jsonfile>`.
 
     Then add the configuration for the file name you just declared.
-
     Example: :ref:`the default config for package.json <default-package-json>`.
+
+    If a JSON file is configured on ``[nitpick.JSONFile] file_names``, then a configuration for it should exist.
+    Otherwise, a style validation error will be raised.
     """
 
     has_multiple_files = True
     error_base_number = 340
 
+    nested_field = JSONFileSchema
+
     SOME_VALUE_PLACEHOLDER = "<some value here>"
 
     def check_rules(self) -> YieldFlake8Error:
@@ -57,10 +72,15 @@ def _check_contained_keys(self) -> YieldFlake8Error:
 
     def _check_contained_json(self) -> YieldFlake8Error:
         actual_fmt = JsonFormat(path=self.file_path)
-        expected = {
-            # FIXME: deal with invalid JSON
-            # TODO: accept key as a jmespath expression, value is valid JSON
-            key: json.loads(json_string)
-            for key, json_string in (self.file_dict.get(KEY_CONTAINS_JSON) or {}).items()
-        }
+        expected = {}
+        # TODO: accept key as a jmespath expression, value is valid JSON
+        for key, json_string in (self.file_dict.get(KEY_CONTAINS_JSON) or {}).items():
+            try:
+                expected[key] = json.loads(json_string)
+            except json.JSONDecodeError as err:
+                # This should not happen, because the style was already validated before.
+                # Maybe the NIP??? code was disabled by the user?
+                LOGGER.error("%s on %s while checking %s", err, KEY_CONTAINS_JSON, self.file_path)
+                continue
+
         yield from self.warn_missing_different(JsonFormat(data=actual_fmt.as_data).compare_with_dictdiffer(expected))

src/nitpick/generic.py

@@ -207,3 +207,8 @@ def is_url(url: str) -> bool:
     True
     """
     return url.startswith("http")
+
+
+def pretty_exception(err: Exception, message: str):
+    """Return a pretty error message with the full path of the Exception."""
+    return "{} ({}.{}: {})".format(message, err.__module__, err.__class__.__name__, str(err))

src/nitpick/schemas.py

@@ -1,21 +1,14 @@
 """Marshmallow schemas."""
 from typing import Dict
 
-from marshmallow import Schema, ValidationError, fields
+from marshmallow import Schema
 from marshmallow_polyfield import PolyField
 from sortedcontainers import SortedDict
 
+from nitpick import fields
 from nitpick.constants import READ_THE_DOCS_URL
 from nitpick.files.setup_cfg import SetupCfgFile
 from nitpick.generic import flatten
-from nitpick.validators import TrimmedLength
-
-
-class NotEmptyString(fields.String):
-    """A string field that must not be empty even after trimmed."""
-
-    def __init__(self, **kwargs):
-        super().__init__(validate=TrimmedLength(min=1), **kwargs)
 
 
 def flatten_marshmallow_errors(errors: Dict) -> str:
@@ -35,36 +28,6 @@ def flatten_marshmallow_errors(errors: Dict) -> str:
     return "\n".join(formatted)
 
 
-def string_or_list_field(object_dict, parent_object_dict):  # pylint: disable=unused-argument
-    """Detect if the field is a string or a list."""
-    if isinstance(object_dict, list):
-        return fields.List(NotEmptyString(required=True, allow_none=False))
-    return NotEmptyString()
-
-
-def validate_section_dot_field(section_field: str) -> bool:
-    """Validate if the combinatio section/field has a dot separating them."""
-    # FIXME: add tests for these situations
-    common = "Use this format: section_name.field_name"
-    if "." not in section_field:
-        raise ValidationError("Dot is missing. {}".format(common))
-    parts = section_field.split(".")
-    if len(parts) > 2:
-        raise ValidationError("There's more than one dot. {}".format(common))
-    if not parts[0].strip():
-        raise ValidationError("Empty section name. {}".format(common))
-    if not parts[1].strip():
-        raise ValidationError("Empty field name. {}".format(common))
-    return True
-
-
-def boolean_or_dict_field(object_dict, parent_object_dict):  # pylint: disable=unused-argument
-    """Detect if the field is a boolean or a dict."""
-    if isinstance(object_dict, dict):
-        return fields.Dict
-    return fields.Bool
-
-
 def help_message(sentence: str, help_page: str) -> str:
     """Show help with the documentation URL on validation errors."""
     clean_sentence = sentence.strip(" .")
@@ -82,19 +45,19 @@ class ToolNitpickSectionSchema(BaseNitpickSchema):
 
     error_messages = {"unknown": help_message("Unknown configuration", "tool_nitpick_section.html")}
 
-    style = PolyField(deserialization_schema_selector=string_or_list_field)
+    style = PolyField(deserialization_schema_selector=fields.string_or_list_field)
 
 
 class NitpickStylesSectionSchema(BaseNitpickSchema):
     """Validation schema for the ``[nitpick.styles]`` section on the style file."""
 
     error_messages = {"unknown": help_message("Unknown configuration", "nitpick_section.html#nitpick-styles")}
 
-    include = PolyField(deserialization_schema_selector=string_or_list_field)
+    include = PolyField(deserialization_schema_selector=fields.string_or_list_field)
 
 
-class NitpickJsonFileSectionSchema(BaseNitpickSchema):
-    """Validation schema for the ``[nitpick.JsonFile]`` section on the style file."""
+class NitpickJSONFileSectionSchema(BaseNitpickSchema):
+    """Validation schema for the ``[nitpick.JSONFile]`` section on the style file."""
 
     error_messages = {"unknown": help_message("Unknown configuration", "nitpick_section.html#nitpick-jsonfile")}
 
@@ -106,28 +69,28 @@ class SetupCfgSchema(BaseNitpickSchema):
 
     error_messages = {"unknown": help_message("Unknown configuration", "nitpick_section.html#comma-separated-values")}
 
-    comma_separated_values = fields.List(fields.String(validate=validate_section_dot_field))
+    comma_separated_values = fields.List(fields.String(validate=fields.validate_section_dot_field))
 
 
 class NitpickFilesSectionSchema(BaseNitpickSchema):
     """Validation schema for the ``[nitpick.files]`` section on the style file."""
 
     error_messages = {"unknown": help_message("Unknown file", "nitpick_section.html#nitpick-files")}
 
-    absent = fields.Dict(NotEmptyString(), fields.String())
-    present = fields.Dict(NotEmptyString(), fields.String())
+    absent = fields.Dict(fields.FilledString, fields.String())
+    present = fields.Dict(fields.FilledString, fields.String())
     # TODO: load this schema dynamically, then add this next field setup_cfg
     setup_cfg = fields.Nested(SetupCfgSchema, data_key=SetupCfgFile.file_name)
 
 
 class NitpickSectionSchema(BaseNitpickSchema):
     """Validation schema for the ``[nitpick]`` section on the style file."""
 
-    minimum_version = NotEmptyString()
+    minimum_version = fields.FilledString()
     styles = fields.Nested(NitpickStylesSectionSchema)
     files = fields.Nested(NitpickFilesSectionSchema)
-    # TODO: load this schema dynamically, then add this next field JsonFile
-    JsonFile = fields.Nested(NitpickJsonFileSectionSchema)
+    # TODO: load this schema dynamically, then add this next field JSONFile
+    JSONFile = fields.Nested(NitpickJSONFileSectionSchema)
 
 
 class BaseStyleSchema(Schema):