feat: introduce DOC503 for checking specific raised exceptions (#161)

Co-authored-by: jsh9 <25124332+jsh9@users.noreply.github.com>

CHANGELOG.md

@@ -1,6 +1,11 @@
 # Change Log
 
-## [unpublished] - 2024-08-05
+## [0.5.7] - 2024-09-02
+
+- Added
+
+  - A new violation code, `DOC503`, which checks that exceptions in the
+    function body match those in the "Raises" section of the docstring
 
 - Changed
   - Switched from tab to 4 spaces in baseline

docs/violation_codes.md

@@ -87,6 +87,7 @@ have a return section.
 | -------- | --------------------------------------------------------------------------------------------------------- |
 | `DOC501` | Function/method has "raise" statements, but the docstring does not have a "Raises" section                |
 | `DOC502` | Function/method has a "Raises" section in the docstring, but there are not "raise" statements in the body |
+| `DOC503` | Exceptions in the "Raises" section in the docstring do not match those in the function body               |
 
 ## 6. `DOC6xx`: Violations about class attributes
 

pydoclint/utils/return_yield_raise.py

@@ -1,5 +1,5 @@
 import ast
-from typing import Callable, Dict, Tuple, Type
+from typing import Callable, Dict, Generator, List, Optional, Tuple, Type
 
 from pydoclint.utils import walk
 from pydoclint.utils.annotation import unparseAnnotation
@@ -93,6 +93,67 @@ def isThisNodeARaiseStmt(node_: ast.AST) -> bool:
     return _hasExpectedStatements(node, isThisNodeARaiseStmt)
 
 
+def getRaisedExceptions(node: FuncOrAsyncFuncDef) -> List[str]:
+    """Get the raised exceptions in a function node as a sorted list"""
+    return sorted(set(_getRaisedExceptions(node)))
+
+
+def _getRaisedExceptions(
+        node: FuncOrAsyncFuncDef,
+) -> Generator[str, None, None]:
+    """Yield the raised exceptions in a function node"""
+    childLineNum: int = -999
+
+    # key: child lineno, value: (parent lineno, is parent a function?)
+    familyTree: Dict[int, Tuple[int, bool]] = {}
+
+    currentParentExceptHandler: Optional[ast.ExceptHandler] = None
+
+    # Depth-first guarantees the last-seen exception handler
+    # is a parent of child.
+    for child, parent in walk.walk_dfs(node):
+        childLineNum = _updateFamilyTree(child, parent, familyTree)
+
+        if isinstance(parent, ast.ExceptHandler):
+            currentParentExceptHandler = parent
+
+        if (
+            isinstance(child, ast.Raise)
+            and isinstance(
+                parent,
+                (ast.AsyncFunctionDef, ast.FunctionDef, BlockType),
+            )
+            and _confirmThisStmtIsNotWithinNestedFunc(
+                foundStatementTemp=True,
+                familyTree=familyTree,
+                lineNumOfStatement=childLineNum,
+                lineNumOfThisNode=node.lineno,
+            )
+        ):
+            for subnode, _ in walk.walk_dfs(child):
+                if isinstance(subnode, ast.Name):
+                    yield subnode.id
+                    break
+            else:
+                # if "raise" statement was alone, it must be inside an "except"
+                if currentParentExceptHandler:
+                    yield from _extractExceptionsFromExcept(
+                        currentParentExceptHandler,
+                    )
+
+
+def _extractExceptionsFromExcept(
+        node: ast.ExceptHandler,
+) -> Generator[str, None, None]:
+    if isinstance(node.type, ast.Name):
+        yield node.type.id
+
+    if isinstance(node.type, ast.Tuple):
+        for child, _ in walk.walk(node.type):
+            if isinstance(child, ast.Name):
+                yield child.id
+
+
 def _hasExpectedStatements(
         node: FuncOrAsyncFuncDef,
         isThisNodeAnExpectedStmt: Callable[[ast.AST], bool],

pydoclint/utils/violation.py

@@ -52,6 +52,7 @@
 
     501: 'has "raise" statements, but the docstring does not have a "Raises" section',
     502: 'has a "Raises" section in the docstring, but there are not "raise" statements in the body',
+    503: 'exceptions in the "Raises" section in the docstring do not match those in the function body',
 
     601: 'Class docstring contains fewer class attributes than actual class attributes.',
     602: 'Class docstring contains more class attributes than in actual class attributes.',

pydoclint/utils/visitor_helper.py

@@ -521,3 +521,30 @@ def extractReturnTypeFromGenerator(returnAnnoText: str) -> str:
         returnType = returnAnnoText
 
     return stripQuotes(returnType)
+
+
+def addMismatchedRaisesExceptionViolation(
+        *,
+        docRaises: List[str],
+        actualRaises: List[str],
+        violations: List[Violation],
+        violationForRaisesMismatch: Violation,  # such as V503
+        lineNum: int,
+        msgPrefix: str,
+) -> None:
+    """
+    Add a violation for mismatched exception type between function
+    body and docstring
+    """
+    msgPostfix: str = (
+        f'Raises values in the docstring: {docRaises}.'
+        f' Raised exceptions in the body: {actualRaises}.'
+    )
+    violations.append(
+        Violation(
+            code=violationForRaisesMismatch.code,
+            line=lineNum,
+            msgPrefix=msgPrefix,
+            msgPostfix=msgPostfix,
+        )
+    )

pydoclint/utils/walk.py

@@ -32,6 +32,13 @@ def walk(node):
         yield node, parent
 
 
+def walk_dfs(node):
+    """Depth-first traversal of AST. Modified from `walk()` in this file"""
+    for child, parent in iter_child_nodes(node):
+        yield child, parent
+        yield from walk_dfs(child)
+
+
 def iter_child_nodes(node):
     """
     Yield all direct child nodes of *node*, that is, all fields that are nodes

pydoclint/visitor.py

@@ -17,6 +17,7 @@
 from pydoclint.utils.return_anno import ReturnAnnotation
 from pydoclint.utils.return_arg import ReturnArg
 from pydoclint.utils.return_yield_raise import (
+    getRaisedExceptions,
     hasGeneratorAsReturnAnnotation,
     hasIteratorOrIterableAsReturnAnnotation,
     hasRaiseStatements,
@@ -32,6 +33,7 @@
 )
 from pydoclint.utils.violation import Violation
 from pydoclint.utils.visitor_helper import (
+    addMismatchedRaisesExceptionViolation,
     checkClassAttributesAgainstClassDocstring,
     checkDocArgsLengthAgainstActualArgs,
     checkNameOrderAndTypeHintsOfDocArgsAgainstActualArgs,
@@ -811,6 +813,7 @@ def checkRaises(
 
         v501 = Violation(code=501, line=lineNum, msgPrefix=msgPrefix)
         v502 = Violation(code=502, line=lineNum, msgPrefix=msgPrefix)
+        v503 = Violation(code=503, line=lineNum, msgPrefix=msgPrefix)
 
         docstringHasRaisesSection: bool = doc.hasRaisesSection
         hasRaiseStmt: bool = hasRaiseStatements(node)
@@ -822,4 +825,31 @@ def checkRaises(
             if not self.isAbstractMethod:
                 violations.append(v502)
 
+        # check that the raise statements match those in body.
+        if hasRaiseStmt:
+            docRaises: List[str] = []
+
+            for raises in doc.parsed.raises:
+                if raises.type_name:
+                    docRaises.append(raises.type_name)
+                elif doc.style == 'sphinx' and raises.description:
+                    # :raises: Exception: -> 'Exception'
+                    splitDesc = raises.description.split(':')
+                    if len(splitDesc) > 1 and ' ' not in splitDesc[0].strip():
+                        exc = splitDesc[0].strip()
+                        docRaises.append(exc)
+
+            docRaises.sort()
+            actualRaises = getRaisedExceptions(node)
+
+            if docRaises != actualRaises:
+                addMismatchedRaisesExceptionViolation(
+                    docRaises=docRaises,
+                    actualRaises=actualRaises,
+                    violations=violations,
+                    violationForRaisesMismatch=v503,
+                    lineNum=lineNum,
+                    msgPrefix=msgPrefix,
+                )
+
         return violations

setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = pydoclint
-version = 0.5.6
+version = 0.5.7
 description = A Python docstring linter that checks arguments, returns, yields, and raises sections
 long_description = file: README.md
 long_description_content_type = text/markdown

tests/data/google/raises/cases.py

@@ -143,3 +143,42 @@ def inner9a(arg1) -> None:
                 raise
 
         print(arg0)
+
+    def func11(self, arg0) -> None:
+        """
+        This docstring doesn't specify all the raised exceptions.
+
+        Args:
+            arg0: Arg 0
+
+        Raises:
+            TypeError: if arg0 is 0.
+        """
+        if arg0 == 0:
+            raise TypeError
+        raise ValueError
+
+    def func12(self, arg0) -> None:
+        """
+        There should not be any violations in this method.
+
+        Args:
+            arg0: Arg 0
+
+        Raises:
+            TypeError: if arg0 is 0.
+            ValueError: otherwise.
+        """
+        if arg0 == 0:
+            raise TypeError
+        raise ValueError
+
+    def func13(self) -> None:
+        """
+        Should raise an error due to duplicated raises.
+
+        Raises:
+            ValueError: all the time.
+            ValueError: typo!
+        """
+        raise ValueError

tests/data/numpy/raises/cases.py

@@ -178,3 +178,54 @@ def inner9a(arg1) -> None:
                 raise
 
         print(arg0)
+
+    def func11(self, arg0) -> None:
+        """
+        This docstring doesn't specify all the raised exceptions.
+
+        Parameters
+        ----------
+        arg0
+            Arg 0
+
+        Raises
+        ------
+        TypeError
+            if arg0 is 0.
+        """
+        if arg0 == 0:
+            raise TypeError
+        raise ValueError
+
+    def func12(self, arg0) -> None:
+        """
+        There should not be any violations in this method.
+
+        Parameters
+        ----------
+        arg0
+            Arg 0
+
+        Raises
+        ------
+        TypeError
+            if arg0 is 0.
+        ValueError
+            otherwise.
+        """
+        if arg0 == 0:
+            raise TypeError
+        raise ValueError
+
+    def func13(self) -> None:
+        """
+        Should raise an error due to duplicated raises.
+
+        Raises
+        ------
+        ValueError
+            all the time.
+        ValueError
+            typo!
+        """
+        raise ValueError

tests/data/sphinx/raises/cases.py

@@ -121,3 +121,35 @@ def inner9a(arg1) -> None:
                 raise
 
         print(arg0)
+
+    def func11(self, arg0) -> None:
+        """
+        This docstring doesn't specify all the raised exceptions.
+
+        :param arg0: Arg 0
+        :raises TypeError: if arg0 is zero.
+        """
+        if arg0 == 0:
+            raise TypeError
+        raise ValueError
+
+    def func12(self, arg0) -> None:
+        """
+        There should not be any violations in this method.
+
+        :param arg0: Arg 0
+        :raises TypeError: if arg0 is zero.
+        :raises ValueError: otherwise.
+        """
+        if arg0 == 0:
+            raise TypeError
+        raise ValueError
+
+    def func13(self) -> None:
+        """
+        Should raise an error due to duplicated raises.
+
+        :raises ValueError: all the time.
+        :raises ValueError: typo!
+        """
+        raise ValueError

tests/test_main.py

@@ -609,6 +609,9 @@ def testAllowInitDocstring(style: str) -> None:
         'because __init__() cannot return anything',
         'DOC305: Class `C`: Class docstring has a "Raises" section; please put it in '
         'the __init__() docstring',
+        'DOC503: Method `C.__init__` exceptions in the "Raises" section in the '
+        'docstring do not match those in the function body Raises values in the '
+        "docstring: ['TypeError']. Raised exceptions in the body: ['ValueError'].",
         'DOC306: Class `D`: The class docstring does not need a "Yields" section, '
         'because __init__() cannot yield anything',
         'DOC307: Class `D`: The __init__() docstring does not need a "Yields" '
@@ -804,6 +807,12 @@ def testRaises(style: str, skipRaisesCheck: bool) -> None:
     expected0 = [
         'DOC501: Method `B.func1` has "raise" statements, but the docstring does not '
         'have a "Raises" section',
+        'DOC503: Method `B.func1` exceptions in the "Raises" section in the docstring '
+        'do not match those in the function body Raises values in the docstring: []. '
+        "Raised exceptions in the body: ['ValueError'].",
+        'DOC503: Method `B.func4` exceptions in the "Raises" section in the docstring '
+        'do not match those in the function body Raises values in the docstring: '
+        "['CurtomError']. Raised exceptions in the body: ['CustomError'].",
         'DOC502: Method `B.func5` has a "Raises" section in the docstring, but there '
         'are not "raise" statements in the body',
         'DOC502: Method `B.func7` has a "Raises" section in the docstring, but there '
@@ -812,6 +821,17 @@ def testRaises(style: str, skipRaisesCheck: bool) -> None:
         'are not "raise" statements in the body',
         'DOC501: Function `inner9a` has "raise" statements, but the docstring does '
         'not have a "Raises" section',
+        'DOC503: Function `inner9a` exceptions in the "Raises" section in the '
+        'docstring do not match those in the function body Raises values in the '
+        "docstring: []. Raised exceptions in the body: ['FileNotFoundError'].",
+        'DOC503: Method `B.func11` exceptions in the "Raises" section in the '
+        'docstring do not match those in the function body Raises values in the '
+        "docstring: ['TypeError']. Raised exceptions in the body: ['TypeError', "
+        "'ValueError'].",
+        'DOC503: Method `B.func13` exceptions in the "Raises" section in the '
+        'docstring do not match those in the function body Raises values in the '
+        "docstring: ['ValueError', 'ValueError']. Raised exceptions in the body: "
+        "['ValueError'].",
     ]
     expected1 = []
     expected = expected1 if skipRaisesCheck else expected0
@@ -841,6 +861,9 @@ def testRaisesPy310plus(style: str, skipRaisesCheck: bool) -> None:
     expected0 = [
         'DOC501: Method `B.func10` has "raise" statements, but the docstring does not '
         'have a "Raises" section',
+        'DOC503: Method `B.func10` exceptions in the "Raises" section in the '
+        'docstring do not match those in the function body Raises values in the '
+        "docstring: []. Raised exceptions in the body: ['ValueError'].",
     ]
     expected1 = []
     expected = expected1 if skipRaisesCheck else expected0