Move validation to jsonschema

README.md

@@ -183,7 +183,7 @@ After a readme is assembled out of fragments, it's possible to run an arbitrary
 [[tool.hatch.metadata.hooks.fancy-pypi-readme.substitutions]]
 pattern = "This is a (.*) that we'll replace later."
 replacement = "It was a '\\1'!"
-ignore_case = true  # optional; false by default
+ignore-case = true  # optional; false by default
 ```
 
 ---

pyproject.toml

@@ -29,6 +29,7 @@ classifiers = [
 ]
 dependencies = [
   "hatchling",
+  "jsonschema",
   "tomli; python_version<'3.11'",
   "typing-extensions; python_version<'3.8'",
 ]
@@ -116,9 +117,13 @@ profile = "attrs"
 
 
 [tool.mypy]
+show_error_codes = true
+enable_error_code = ["ignore-without-code"]
 strict = true
 follow_imports = "normal"
 warn_no_return = true
+ignore_missing_imports = true
+
 
 [[tool.mypy.overrides]]
 module = "tests.*"

src/hatch_fancy_pypi_readme/_config.py

@@ -7,8 +7,11 @@
 from dataclasses import dataclass
 from typing import Any
 
-from ._fragments import Fragment, load_fragments
-from ._substitutions import Substituter, load_substitutions
+from jsonschema import Draft202012Validator
+
+from ._fragments import VALID_FRAGMENTS, Fragment
+from ._humanize_validation_errors import errors_to_human_strings
+from ._substitutions import Substituter
 from .exceptions import ConfigurationError
 
 
@@ -19,36 +22,97 @@ class Config:
     substitutions: list[Substituter]
 
 
+SCHEMA = {
+    "type": "object",
+    "properties": {
+        "content-type": {
+            "type": "string",
+            "enum": ["text/markdown", "text/x-rst"],
+        },
+        "fragments": {
+            "type": "array",
+            "minItems": 1,
+            # Items are validated separately for better error messages.
+            "items": {"type": "object"},
+        },
+        "substitutions": {
+            "type": "array",
+            "items": {
+                "type": "object",
+                "properties": {
+                    "pattern": {"type": "string", "format": "regex"},
+                    "replacement": {"type": "string"},
+                    "ignore-case": {"type": "boolean"},
+                },
+                "required": ["pattern", "replacement"],
+                "additionalProperties": False,
+            },
+        },
+    },
+    "required": ["content-type", "fragments"],
+    "additionalProperties": False,
+}
+
+V = Draft202012Validator(
+    SCHEMA, format_checker=Draft202012Validator.FORMAT_CHECKER
+)
+
+
 def load_and_validate_config(config: dict[str, Any]) -> Config:
-    errs = []
+    errs = sorted(
+        V.iter_errors(config),
+        key=lambda e: e.path,  # type: ignore[no-any-return]
+    )
+    if errs:
+        raise ConfigurationError(errors_to_human_strings(errs))
+
+    return Config(
+        config["content-type"],
+        _load_fragments(config["fragments"]),
+        [
+            Substituter.from_config(sub_cfg)
+            for sub_cfg in config.get("substitutions", [])
+        ],
+    )
+
+
+def _load_fragments(config: list[dict[str, str]]) -> list[Fragment]:
+    """
+    Load fragments from *config*.
+
+    This is a bit more complicated because validating the fragments field using
+    `oneOf` leads to unhelpful error messages that are difficult to convert
+    into something humanly meaningful.
+
+    So we detect first, validate using jsonschema and try to load them. They
+    still may fail loading if they refer to files and lack markers / the
+    pattern doesn't match.
+    """
     frags = []
+    errs = []
 
-    if "content-type" not in config:
-        errs.append(
-            "Missing tool.hatch.metadata.hooks.fancy-pypi-readme.content-type "
-            "setting."
-        )
-
-    try:
-        try:
-            frag_cfg_list = config["fragments"]
-        except KeyError:
-            errs.append(
-                "Missing tool.hatch.metadata.hooks.fancy-pypi-readme.fragments"
-                " setting."
-            )
-        else:
-            frags = load_fragments(frag_cfg_list)
+    for i, frag_cfg in enumerate(config):
+        for frag in VALID_FRAGMENTS:
+            if frag.key not in frag_cfg:
+                continue
 
-    except ConfigurationError as e:
-        errs.extend(e.errors)
+            try:
+                ves = tuple(frag.validator.iter_errors(frag_cfg))
+                if ves:
+                    raise ConfigurationError(
+                        errors_to_human_strings(ves, ("fragments", i))
+                    )
+                frags.append(frag.from_config(frag_cfg))
+            except ConfigurationError as e:
+                errs.extend(e.errors)
 
-    try:
-        subs = load_substitutions(config.get("substitutions", []))
-    except ConfigurationError as e:
-        errs.extend(e.errors)
+            # We have either detecte and added or detected and errored, but in
+            # any case we're done with this fragment.
+            break
+        else:
+            errs.append(f"Unknown fragment type {frag_cfg!r}.")
 
     if errs:
         raise ConfigurationError(errs)
 
-    return Config(config["content-type"], frags, subs)
+    return frags

src/hatch_fancy_pypi_readme/_fragments.py

@@ -11,52 +11,46 @@
 from pathlib import Path
 from typing import ClassVar, Iterable
 
+from jsonschema import Draft202012Validator, Validator
+
 
 if sys.version_info >= (3, 8):
     from typing import Protocol
 else:
     from typing_extensions import Protocol
-from .exceptions import ConfigurationError
-
-
-def load_fragments(config: list[dict[str, str]]) -> list[Fragment]:
-    """
-    Load all fragments from the fragments config list.
-
-    Raise ConfigurationError on unknown or misconfigured ones.
-    """
-    if not config:
-        raise ConfigurationError(
-            [
-                "tool.hatch.metadata.hooks.fancy-pypi-readme.fragments must "
-                "not be empty."
-            ]
-        )
-
-    frags = []
-    errs = []
-    for frag_cfg in config:
-        for frag in _VALID_FRAGMENTS:
-            if frag.key not in frag_cfg:
-                continue
 
-            try:
-                frags.append(frag.from_config(frag_cfg))
-            except ConfigurationError as e:
-                errs.extend(e.errors)
-
-            break
-        else:
-            errs.append(f"Unknown fragment type {frag_cfg!r}.")
+from .exceptions import ConfigurationError
 
-    if errs:
-        raise ConfigurationError(errs)
 
-    return frags
+TEXT_V = Draft202012Validator(
+    {
+        "type": "object",
+        "properties": {"text": {"type": "string", "pattern": ".+"}},
+        "required": ["text"],
+        "additionalProperties": False,
+    },
+    format_checker=Draft202012Validator.FORMAT_CHECKER,
+)
+
+FILE_V = Draft202012Validator(
+    {
+        "type": "object",
+        "properties": {
+            "path": {"type": "string", "pattern": ".+"},
+            "start-after": {"type": "string", "pattern": ".+"},
+            "end-before": {"type": "string", "pattern": ".+"},
+            "pattern": {"type": "string", "format": "regex"},
+        },
+        "required": ["path"],
+        "additionalProperties": False,
+    },
+    format_checker=Draft202012Validator.FORMAT_CHECKER,
+)
 
 
 class Fragment(Protocol):
     key: ClassVar[str]
+    validator: ClassVar[Validator]
 
     @classmethod
     def from_config(self, cfg: dict[str, str]) -> Fragment:
@@ -73,24 +67,13 @@ class TextFragment:
     """
 
     key: ClassVar[str] = "text"
+    validator: ClassVar[Validator] = TEXT_V
 
     _text: str
 
     @classmethod
     def from_config(cls, cfg: dict[str, str]) -> Fragment:
-        contents = cfg.pop(cls.key)
-
-        if not contents:
-            raise ConfigurationError(
-                [f"text fragment: {cls.key} can't be empty."]
-            )
-
-        if cfg:
-            raise ConfigurationError(
-                [f"text fragment: unknown option: {o}" for o in cfg.keys()]
-            )
-
-        return cls(contents)
+        return cls(cfg[cls.key])
 
     def render(self) -> str:
         return self._text
@@ -103,6 +86,7 @@ class FileFragment:
     """
 
     key: ClassVar[str] = "path"
+    validator: ClassVar[Validator] = FILE_V
 
     _contents: str
 
@@ -114,12 +98,11 @@ def from_config(cls, cfg: dict[str, str]) -> Fragment:
         pattern = cfg.pop("pattern", None)
 
         errs: list[str] = []
-        if cfg:
-            errs.extend(
-                f"file fragment: unknown option: {o!r}" for o in cfg.keys()
-            )
 
-        contents = path.read_text(encoding="utf-8")
+        try:
+            contents = path.read_text(encoding="utf-8")
+        except FileNotFoundError:
+            raise ConfigurationError([f"Fragment file '{path}' not found."])
 
         if start_after is not None:
             try:
@@ -138,22 +121,17 @@ def from_config(cls, cfg: dict[str, str]) -> Fragment:
                 )
 
         if pattern:
-            try:
-                m = re.search(pattern, contents, re.DOTALL)
-                if not m:
+            m = re.search(pattern, contents, re.DOTALL)
+            if not m:
+                errs.append(f"file fragment: pattern {pattern!r} not found.")
+            else:
+                try:
+                    contents = m.group(1)
+                except IndexError:
                     errs.append(
-                        f"file fragment: pattern {pattern!r} not found."
+                        "file fragment: pattern matches, but no group "
+                        "defined."
                     )
-                else:
-                    try:
-                        contents = m.group(1)
-                    except IndexError:
-                        errs.append(
-                            "file fragment: pattern matches, but no group "
-                            "defined."
-                        )
-            except re.error as e:
-                errs.append(f"file fragment: invalid pattern {pattern!r}: {e}")
 
         if errs:
             raise ConfigurationError(errs)
@@ -164,4 +142,4 @@ def render(self) -> str:
         return self._contents
 
 
-_VALID_FRAGMENTS: Iterable[type[Fragment]] = (TextFragment, FileFragment)
+VALID_FRAGMENTS: Iterable[type[Fragment]] = (TextFragment, FileFragment)