Avoid enabling all EM checks at once (#1349)

src/checkers/ast.rs

@@ -1067,17 +1067,11 @@ where
                     }
                 }
                 if self.settings.enabled.contains(&CheckCode::EM101)
-                    | self.settings.enabled.contains(&CheckCode::EM102)
-                    | self.settings.enabled.contains(&CheckCode::EM103)
+                    || self.settings.enabled.contains(&CheckCode::EM102)
+                    || self.settings.enabled.contains(&CheckCode::EM103)
                 {
                     if let Some(exc) = exc {
-                        self.add_checks(
-                            flake8_errmsg::checks::check_string_in_exception(
-                                exc,
-                                self.settings.flake8_errmsg.max_string_length,
-                            )
-                            .into_iter(),
-                        );
+                        flake8_errmsg::plugins::string_in_exception(self, exc);
                     }
                 }
             }

src/flake8_errmsg/mod.rs

@@ -1,4 +1,4 @@
-pub mod checks;
+pub mod plugins;
 pub mod settings;
 
 #[cfg(test)]

src/flake8_errmsg/plugins.rs

@@ -0,0 +1,52 @@
+use rustpython_ast::{Constant, Expr, ExprKind};
+
+use crate::ast::types::Range;
+use crate::checkers::ast::Checker;
+use crate::checks::{Check, CheckCode, CheckKind};
+
+/// EM101, EM102, EM103
+pub fn string_in_exception(checker: &mut Checker, exc: &Expr) {
+    if let ExprKind::Call { args, .. } = &exc.node {
+        if let Some(first) = args.first() {
+            match &first.node {
+                // Check for string literals
+                ExprKind::Constant {
+                    value: Constant::Str(string),
+                    ..
+                } => {
+                    if checker.settings.enabled.contains(&CheckCode::EM101) {
+                        if string.len() > checker.settings.flake8_errmsg.max_string_length {
+                            checker.add_check(Check::new(
+                                CheckKind::RawStringInException,
+                                Range::from_located(first),
+                            ));
+                        }
+                    }
+                }
+                // Check for f-strings
+                ExprKind::JoinedStr { .. } => {
+                    if checker.settings.enabled.contains(&CheckCode::EM102) {
+                        checker.add_check(Check::new(
+                            CheckKind::FStringInException,
+                            Range::from_located(first),
+                        ));
+                    }
+                }
+                // Check for .format() calls
+                ExprKind::Call { func, .. } => {
+                    if checker.settings.enabled.contains(&CheckCode::EM103) {
+                        if let ExprKind::Attribute { value, attr, .. } = &func.node {
+                            if attr == "format" && matches!(value.node, ExprKind::Constant { .. }) {
+                                checker.add_check(Check::new(
+                                    CheckKind::DotFormatInException,
+                                    Range::from_located(first),
+                                ));
+                            }
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+}