[pyupgrade] Better messages and diagnostic range (UP015) (#15872)

## Summary

Resolves #15863.

In preview, diagnostic ranges will now be limited to that of the
argument. Rule documentation, variable names, error messages and fix
titles have all been modified to use "argument" consistently.

## Test Plan

`cargo nextest run` and `cargo insta test`.

Author: InSyncWithFoo

crates/ruff_linter/src/rules/pyupgrade/mod.rs

@@ -118,6 +118,25 @@ mod tests {
         Ok(())
     }
 
+    #[test_case(Rule::RedundantOpenModes, Path::new("UP015.py"))]
+    #[test_case(Rule::RedundantOpenModes, Path::new("UP015_1.py"))]
+    fn preview_rules(rule_code: Rule, path: &Path) -> Result<()> {
+        let snapshot = format!(
+            "preview__{}_{}",
+            rule_code.noqa_code(),
+            path.to_string_lossy()
+        );
+        let diagnostics = test_path(
+            Path::new("pyupgrade").join(path).as_path(),
+            &settings::LinterSettings {
+                preview: PreviewMode::Enabled,
+                ..settings::LinterSettings::for_rule(rule_code)
+            },
+        )?;
+        assert_messages!(snapshot, diagnostics);
+        Ok(())
+    }
+
     #[test]
     fn up007_preview() -> Result<()> {
         let diagnostics = test_path(

crates/ruff_linter/src/rules/pyupgrade/rules/redundant_open_modes.rs

@@ -2,18 +2,17 @@ use anyhow::Result;
 use ruff_diagnostics::{AlwaysFixableViolation, Diagnostic, Edit, Fix};
 use ruff_macros::{derive_message_formats, ViolationMetadata};
 use ruff_python_ast::{self as ast, Expr};
-use ruff_python_codegen::Stylist;
 use ruff_python_parser::{TokenKind, Tokens};
 use ruff_python_stdlib::open_mode::OpenMode;
 use ruff_text_size::{Ranged, TextSize};
 
 use crate::checkers::ast::Checker;
 
 /// ## What it does
-/// Checks for redundant `open` mode parameters.
+/// Checks for redundant `open` mode arguments.
 ///
 /// ## Why is this bad?
-/// Redundant `open` mode parameters are unnecessary and should be removed to
+/// Redundant `open` mode arguments are unnecessary and should be removed to
 /// avoid confusion.
 ///
 /// ## Example
@@ -40,18 +39,18 @@ impl AlwaysFixableViolation for RedundantOpenModes {
     fn message(&self) -> String {
         let RedundantOpenModes { replacement } = self;
         if replacement.is_empty() {
-            "Unnecessary open mode parameters".to_string()
+            "Unnecessary mode argument".to_string()
         } else {
-            format!("Unnecessary open mode parameters, use \"{replacement}\"")
+            format!("Unnecessary modes, use `{replacement}`")
         }
     }
 
     fn fix_title(&self) -> String {
         let RedundantOpenModes { replacement } = self;
         if replacement.is_empty() {
-            "Remove open mode parameters".to_string()
+            "Remove mode argument".to_string()
         } else {
-            format!("Replace with \"{replacement}\"")
+            format!("Replace with `{replacement}`")
         }
     }
 }
@@ -71,68 +70,71 @@ pub(crate) fn redundant_open_modes(checker: &mut Checker, call: &ast::ExprCall)
         return;
     }
 
-    let Some(mode_param) = call.arguments.find_argument_value("mode", 1) else {
+    let Some(mode_arg) = call.arguments.find_argument_value("mode", 1) else {
         return;
     };
-    let Expr::StringLiteral(ast::ExprStringLiteral { value, .. }) = &mode_param else {
+    let Expr::StringLiteral(ast::ExprStringLiteral { value, .. }) = &mode_arg else {
         return;
     };
     let Ok(mode) = OpenMode::from_chars(value.chars()) else {
         return;
     };
     let reduced = mode.reduce();
     if reduced != mode {
-        checker.diagnostics.push(create_diagnostic(
-            call,
-            mode_param,
-            reduced,
-            checker.tokens(),
-            checker.stylist(),
-        ));
+        checker
+            .diagnostics
+            .push(create_diagnostic(call, mode_arg, reduced, checker));
     }
 }
 
 fn create_diagnostic(
     call: &ast::ExprCall,
-    mode_param: &Expr,
+    mode_arg: &Expr,
     mode: OpenMode,
-    tokens: &Tokens,
-    stylist: &Stylist,
+    checker: &Checker,
 ) -> Diagnostic {
+    let range = if checker.settings.preview.is_enabled() {
+        mode_arg.range()
+    } else {
+        call.range
+    };
+
     let mut diagnostic = Diagnostic::new(
         RedundantOpenModes {
             replacement: mode.to_string(),
         },
-        call.range(),
+        range,
     );
 
     if mode.is_empty() {
-        diagnostic
-            .try_set_fix(|| create_remove_param_fix(call, mode_param, tokens).map(Fix::safe_edit));
+        diagnostic.try_set_fix(|| {
+            create_remove_argument_fix(call, mode_arg, checker.tokens()).map(Fix::safe_edit)
+        });
     } else {
+        let stylist = checker.stylist();
         diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
             format!("{}{mode}{}", stylist.quote(), stylist.quote()),
-            mode_param.range(),
+            mode_arg.range(),
         )));
     }
 
     diagnostic
 }
 
-fn create_remove_param_fix(
+fn create_remove_argument_fix(
     call: &ast::ExprCall,
-    mode_param: &Expr,
+    mode_arg: &Expr,
     tokens: &Tokens,
 ) -> Result<Edit> {
-    // Find the last comma before mode_param and create a deletion fix
-    // starting from the comma and ending after mode_param.
+    // Find the last comma before mode_arg and create a deletion fix
+    // starting from the comma and ending after mode_arg.
     let mut fix_start: Option<TextSize> = None;
     let mut fix_end: Option<TextSize> = None;
     let mut is_first_arg: bool = false;
     let mut delete_first_arg: bool = false;
 
     for token in tokens.in_range(call.range()) {
-        if token.start() == mode_param.start() {
+        if token.start() == mode_arg.start() {
             if is_first_arg {
                 delete_first_arg = true;
                 continue;