feat: implement TRY200

README.md

@@ -1195,6 +1195,7 @@ 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 | 🛠 |
+| TRY200 | reraise-no-cause | Use `raise from` to specify exception cause |  |
 | TRY300 | try-consider-else | Consider `else` block |  |
 
 ### Ruff-specific rules (RUF)

resources/test/fixtures/tryceratops/TRY200.py

@@ -0,0 +1,24 @@
+class MyException(Exception):
+    pass
+
+
+class MainFunctionFailed(Exception):
+    pass
+
+
+def process():
+    raise MyException
+
+
+def bad():
+    try:
+        process()
+    except MyException:
+        raise MainFunctionFailed()
+
+
+def good():
+    try:
+        process()
+    except MyException as ex:
+        raise MainFunctionFailed() from ex

ruff.schema.json

@@ -1751,6 +1751,9 @@
         "TRY0",
         "TRY00",
         "TRY004",
+        "TRY2",
+        "TRY20",
+        "TRY200",
         "TRY3",
         "TRY30",
         "TRY300",

src/checkers/ast.rs

@@ -3306,6 +3306,9 @@ where
                         body,
                     );
                 }
+                if self.settings.rules.enabled(&Rule::ReraiseNoCause) {
+                    tryceratops::rules::reraise_no_cause(self, body);
+                }
                 match name {
                     Some(name) => {
                         if self.settings.rules.enabled(&Rule::AmbiguousVariableName) {

src/registry.rs

@@ -429,6 +429,7 @@ ruff_macros::define_rule_mapping!(
     TYP005 => rules::flake8_type_checking::rules::EmptyTypeCheckingBlock,
     // tryceratops
     TRY004 => rules::tryceratops::rules::PreferTypeError,
+    TRY200 => rules::tryceratops::rules::ReraiseNoCause,
     TRY300 => rules::tryceratops::rules::TryConsiderElse,
     // Ruff
     RUF001 => violations::AmbiguousUnicodeCharacterString,

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::ReraiseNoCause, Path::new("TRY200.py"); "TRY200")]
     #[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 reraise_no_cause::{reraise_no_cause, ReraiseNoCause};
 pub use try_consider_else::{try_consider_else, TryConsiderElse};
 
 mod prefer_type_error;
+mod reraise_no_cause;
 mod try_consider_else;

src/rules/tryceratops/rules/reraise_no_cause.rs

@@ -0,0 +1,32 @@
+use ruff_macros::derive_message_formats;
+use rustpython_ast::{Stmt, StmtKind};
+
+use crate::ast::types::Range;
+use crate::checkers::ast::Checker;
+use crate::define_violation;
+use crate::registry::Diagnostic;
+use crate::violation::Violation;
+
+define_violation!(
+    pub struct ReraiseNoCause;
+);
+impl Violation for ReraiseNoCause {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        format!("Use `raise from` to specify exception cause")
+    }
+}
+
+/// TRY200
+pub fn reraise_no_cause(checker: &mut Checker, body: &[Stmt]) {
+    for stmt in body.iter() {
+        if let StmtKind::Raise { cause, .. } = &stmt.node {
+            if cause.is_none() {
+                checker.diagnostics.push(Diagnostic::new(
+                    ReraiseNoCause,
+                    Range::from_located(stmt),
+                ));
+            }
+        }
+    }
+}

src/rules/tryceratops/snapshots/ruff__rules__tryceratops__tests__reraise-no-cause_TRY200.py.snap

@@ -0,0 +1,15 @@
+---
+source: src/rules/tryceratops/mod.rs
+expression: diagnostics
+---
+- kind:
+    ReraiseNoCause: ~
+  location:
+    row: 17
+    column: 8
+  end_location:
+    row: 17
+    column: 34
+  fix: ~
+  parent: ~
+