feat: Implement TRY201 (#2073)

README.md

@@ -1196,6 +1196,7 @@ For more, see [tryceratops](https://pypi.org/project/tryceratops/1.1.0/) on PyPI
 | Code | Name | Message | Fix |
 | ---- | ---- | ------- | --- |
 | TRY004 | prefer-type-error | Prefer `TypeError` exception for invalid type | 🛠 |
+| TRY201 | verbose-raise | Use `raise` without specifying exception name |  |
 | TRY300 | try-consider-else | Consider `else` block |  |
 
 ### flake8-use-pathlib (PTH)

resources/test/fixtures/tryceratops/TRY201.py

@@ -0,0 +1,54 @@
+"""
+Violation:
+
+Raising an exception using its assigned name is verbose and unrequired
+"""
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class MyException(Exception):
+    pass
+
+
+def bad():
+    try:
+        process()
+    except MyException as e:
+        logger.exception("process failed")
+        raise e
+
+
+def good():
+    try:
+        process()
+    except MyException:
+        logger.exception("process failed")
+        raise
+
+def still_good():
+    try:
+        process()
+    except MyException as e:
+        print(e)
+        raise
+
+
+def bad_that_needs_recursion():
+    try:
+        process()
+    except MyException as e:
+        logger.exception("process failed")
+        if True:
+            raise e
+
+
+def bad_that_needs_recursion_2():
+    try:
+        process()
+    except MyException as e:
+        logger.exception("process failed")
+        if True:
+            def foo():
+                raise e

ruff.schema.json

@@ -1782,6 +1782,9 @@
         "TRY0",
         "TRY00",
         "TRY004",
+        "TRY2",
+        "TRY20",
+        "TRY201",
         "TRY3",
         "TRY30",
         "TRY300",

src/checkers/ast.rs

@@ -1578,6 +1578,9 @@ where
                 if self.settings.rules.enabled(&Rule::TryConsiderElse) {
                     tryceratops::rules::try_consider_else(self, body, orelse);
                 }
+                if self.settings.rules.enabled(&Rule::VerboseRaise) {
+                    tryceratops::rules::verbose_raise(self, handlers);
+                }
             }
             StmtKind::Assign { targets, value, .. } => {
                 if self.settings.rules.enabled(&Rule::DoNotAssignLambda) {

src/registry.rs

@@ -428,6 +428,7 @@ ruff_macros::define_rule_mapping!(
     TYP005 => rules::flake8_type_checking::rules::EmptyTypeCheckingBlock,
     // tryceratops
     TRY004 => rules::tryceratops::rules::PreferTypeError,
+    TRY201 => rules::tryceratops::rules::VerboseRaise,
     TRY300 => rules::tryceratops::rules::TryConsiderElse,
     // flake8-use-pathlib
     PTH100 => rules::flake8_use_pathlib::violations::PathlibAbspath,

src/rules/tryceratops/mod.rs

@@ -14,6 +14,7 @@ mod tests {
     use crate::settings;
 
     #[test_case(Rule::PreferTypeError, Path::new("TRY004.py"); "TRY004")]
+    #[test_case(Rule::VerboseRaise, Path::new("TRY201.py"); "TRY201")]
     #[test_case(Rule::TryConsiderElse, Path::new("TRY300.py"); "TRY300")]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());

src/rules/tryceratops/rules/mod.rs

@@ -1,5 +1,7 @@
 pub use prefer_type_error::{prefer_type_error, PreferTypeError};
 pub use try_consider_else::{try_consider_else, TryConsiderElse};
+pub use verbose_raise::{verbose_raise, VerboseRaise};
 
 mod prefer_type_error;
 mod try_consider_else;
+mod verbose_raise;

src/rules/tryceratops/rules/verbose_raise.rs

@@ -0,0 +1,68 @@
+use ruff_macros::derive_message_formats;
+use rustpython_ast::{Excepthandler, ExcepthandlerKind, Expr, ExprKind, Stmt, StmtKind};
+
+use crate::ast::types::Range;
+use crate::ast::visitor;
+use crate::ast::visitor::Visitor;
+use crate::checkers::ast::Checker;
+use crate::define_violation;
+use crate::registry::Diagnostic;
+use crate::violation::Violation;
+
+define_violation!(
+    pub struct VerboseRaise;
+);
+impl Violation for VerboseRaise {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        format!("Use `raise` without specifying exception name")
+    }
+}
+
+#[derive(Default)]
+struct RaiseStatementVisitor<'a> {
+    raises: Vec<Option<&'a Expr>>,
+}
+
+impl<'a, 'b> Visitor<'b> for RaiseStatementVisitor<'a>
+where
+    'b: 'a,
+{
+    fn visit_stmt(&mut self, stmt: &'b Stmt) {
+        match &stmt.node {
+            StmtKind::Raise { exc, .. } => self.raises.push(exc.as_ref().map(|expr| &**expr)),
+            _ => visitor::walk_stmt(self, stmt),
+        }
+    }
+}
+
+/// TRY201
+pub fn verbose_raise(checker: &mut Checker, handlers: &[Excepthandler]) {
+    for handler in handlers {
+        // If the handler assigned a name to the exception...
+        if let ExcepthandlerKind::ExceptHandler {
+            name: Some(exception_name),
+            body,
+            ..
+        } = &handler.node
+        {
+            let raises = {
+                let mut visitor = RaiseStatementVisitor::default();
+                for stmt in body {
+                    visitor.visit_stmt(stmt);
+                }
+                visitor.raises
+            };
+            for expr in raises.into_iter().flatten() {
+                // ...and the raised object is bound to the same name...
+                if let ExprKind::Name { id, .. } = &expr.node {
+                    if id == exception_name {
+                        checker
+                            .diagnostics
+                            .push(Diagnostic::new(VerboseRaise, Range::from_located(expr)));
+                    }
+                }
+            }
+        }
+    }
+}

src/rules/tryceratops/snapshots/ruff__rules__tryceratops__tests__verbose-raise_TRY201.py.snap

@@ -0,0 +1,35 @@
+---
+source: src/rules/tryceratops/mod.rs
+expression: diagnostics
+---
+- kind:
+    VerboseRaise: ~
+  location:
+    row: 20
+    column: 14
+  end_location:
+    row: 20
+    column: 15
+  fix: ~
+  parent: ~
+- kind:
+    VerboseRaise: ~
+  location:
+    row: 44
+    column: 18
+  end_location:
+    row: 44
+    column: 19
+  fix: ~
+  parent: ~
+- kind:
+    VerboseRaise: ~
+  location:
+    row: 54
+    column: 22
+  end_location:
+    row: 54
+    column: 23
+  fix: ~
+  parent: ~
+