fix(lint): mark whole fragment as incorrect if without key

.changeset/silent-fans-battle.md

@@ -0,0 +1,5 @@
+---
+"@biomejs/biome": patch
+---
+
+Updates the [`useJsxKeyInIterable`](https://biomejs.dev/linter/rules/use-jsx-key-in-iterable/) rule to more closely match the behavior of the ESLint plugin (e.g. mark the whole fragment as incorrect when no key is present). This also adds the option to check shorthand fragments (`<></>`)

crates/biome_js_analyze/src/lint/correctness/use_jsx_key_in_iterable.rs

@@ -3,6 +3,7 @@ use crate::services::semantic::Semantic;
 use biome_analyze::{Rule, RuleDiagnostic, RuleDomain, context::RuleContext, declare_lint_rule};
 use biome_analyze::{RuleSource, RuleSourceKind};
 use biome_console::markup;
+use biome_deserialize_macros::Deserializable;
 use biome_diagnostics::Severity;
 use biome_js_semantic::SemanticModel;
 use biome_js_syntax::{
@@ -11,6 +12,7 @@ use biome_js_syntax::{
     JsxAttributeList, JsxExpressionChild, JsxTagExpression,
 };
 use biome_rowan::{AstNode, AstNodeList, AstSeparatedList, TextRange, declare_node_union};
+use serde::{Deserialize, Serialize};
 
 declare_lint_rule! {
     /// Disallow missing key props in iterators/collection literals.
@@ -36,6 +38,27 @@ declare_lint_rule! {
     /// data.map((x) => <Hello key={x.id}>{x}</Hello>);
     /// ```
     ///
+    /// ## Options
+    ///
+    /// ```json,options
+    /// {
+    ///     "options": {
+    ///         "checkShorthandFragments": true
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// ### checkShorthandFragments
+    ///
+    /// React fragments can not only be created with `<React.Fragment>`, but also with shorthand
+    /// fragments (`<></>`). To also check if those require a key, pass `true` to this option.
+    ///
+    /// #### Usage example
+    ///
+    /// ```jsx,expect_diagnostic,use_options
+    /// data.map((x) => <>{x}</>);
+    /// ```
+    ///
     pub UseJsxKeyInIterable {
         version: "1.6.0",
         name: "useJsxKeyInIterable",
@@ -56,19 +79,30 @@ declare_node_union! {
     pub ReactComponentExpression = JsxTagExpression | JsCallExpression
 }
 
+#[derive(Debug, Default, Clone, Serialize, Deserialize, Deserializable, Eq, PartialEq)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[serde(rename_all = "camelCase", deny_unknown_fields, default)]
+pub struct UseJsxKeyInIterableOptions {
+    /// Set to `true` to check shorthand fragments (`<></>`)
+    check_shorthand_fragments: bool,
+}
+
 impl Rule for UseJsxKeyInIterable {
     type Query = Semantic<UseJsxKeyInIterableQuery>;
     type State = TextRange;
     type Signals = Box<[Self::State]>;
-    type Options = ();
+    type Options = UseJsxKeyInIterableOptions;
 
     fn run(ctx: &RuleContext<Self>) -> Self::Signals {
         let node = ctx.query();
         let model = ctx.model();
+        let options = ctx.options();
         match node {
-            UseJsxKeyInIterableQuery::JsArrayExpression(node) => handle_collections(node, model),
+            UseJsxKeyInIterableQuery::JsArrayExpression(node) => {
+                handle_collections(node, model, options)
+            }
             UseJsxKeyInIterableQuery::JsCallExpression(node) => {
-                handle_iterators(node, model).unwrap_or_default()
+                handle_iterators(node, model, options).unwrap_or_default()
             }
         }
         .into_boxed_slice()
@@ -98,7 +132,11 @@ impl Rule for UseJsxKeyInIterable {
 /// ```jsx
 /// [<h1></h1>, <h1></h1>]
 /// ```
-fn handle_collections(node: &JsArrayExpression, model: &SemanticModel) -> Vec<TextRange> {
+fn handle_collections(
+    node: &JsArrayExpression,
+    model: &SemanticModel,
+    options: &UseJsxKeyInIterableOptions,
+) -> Vec<TextRange> {
     let is_inside_jsx = node.parent::<JsxExpressionChild>().is_some();
     node.elements()
         .iter()
@@ -107,7 +145,7 @@ fn handle_collections(node: &JsArrayExpression, model: &SemanticModel) -> Vec<Te
             // no need to handle spread case, if the spread argument is itself a list it
             // will be handled during list declaration
             let node = AnyJsExpression::cast(node.into_syntax())?;
-            handle_potential_react_component(node, model, is_inside_jsx)
+            handle_potential_react_component(node, model, is_inside_jsx, options)
         })
         .flatten()
         .collect()
@@ -120,7 +158,11 @@ fn handle_collections(node: &JsArrayExpression, model: &SemanticModel) -> Vec<Te
 /// ```jsx
 /// data.map(x => <h1>{x}</h1>)
 /// ```
-fn handle_iterators(node: &JsCallExpression, model: &SemanticModel) -> Option<Vec<TextRange>> {
+fn handle_iterators(
+    node: &JsCallExpression,
+    model: &SemanticModel,
+    options: &UseJsxKeyInIterableOptions,
+) -> Option<Vec<TextRange>> {
     let callee = node.callee().ok()?;
     let member_expression = AnyJsMemberExpression::cast(callee.into_syntax())?;
     let arguments = node.arguments().ok()?;
@@ -164,16 +206,16 @@ fn handle_iterators(node: &JsCallExpression, model: &SemanticModel) -> Option<Ve
     match callback_argument {
         AnyJsExpression::JsFunctionExpression(callback) => {
             let body = callback.body().ok()?;
-            Some(handle_function_body(&body, model, is_inside_jsx))
+            Some(handle_function_body(&body, model, is_inside_jsx, options))
         }
         AnyJsExpression::JsArrowFunctionExpression(callback) => {
             let body = callback.body().ok()?;
             match body {
                 AnyJsFunctionBody::AnyJsExpression(expr) => {
-                    handle_potential_react_component(expr, model, is_inside_jsx)
+                    handle_potential_react_component(expr, model, is_inside_jsx, options)
                 }
                 AnyJsFunctionBody::JsFunctionBody(body) => {
-                    Some(handle_function_body(&body, model, is_inside_jsx))
+                    Some(handle_function_body(&body, model, is_inside_jsx, options))
                 }
             }
         }
@@ -186,6 +228,7 @@ fn handle_function_body(
     node: &JsFunctionBody,
     model: &SemanticModel,
     is_inside_jsx: bool,
+    options: &UseJsxKeyInIterableOptions,
 ) -> Vec<TextRange> {
     // if the return statement definitely has a key prop, don't need to check the rest of the function
     let return_statement = node
@@ -204,7 +247,7 @@ fn handle_function_body(
         .unwrap_or_default();
     let ranges = return_statement.and_then(|ret| {
         let returned_value = ret.argument()?;
-        handle_potential_react_component(returned_value, model, is_inside_jsx)
+        handle_potential_react_component(returned_value, model, is_inside_jsx, options)
     });
     if ranges.is_none() && is_return_component {
         return vec![];
@@ -222,14 +265,14 @@ fn handle_function_body(
                         .filter_map(|declarator| {
                             let decl = declarator.ok()?;
                             let init = decl.initializer()?.expression().ok()?;
-                            handle_potential_react_component(init, model, is_inside_jsx)
+                            handle_potential_react_component(init, model, is_inside_jsx, options)
                         })
                         .flatten()
                         .collect(),
                 )
             } else if let Some(statement) = statement.as_js_return_statement() {
                 let returned_value = statement.argument()?;
-                handle_potential_react_component(returned_value, model, is_inside_jsx)
+                handle_potential_react_component(returned_value, model, is_inside_jsx, options)
             } else {
                 None
             }
@@ -242,14 +285,19 @@ fn handle_potential_react_component(
     node: AnyJsExpression,
     model: &SemanticModel,
     is_inside_jsx: bool,
+    options: &UseJsxKeyInIterableOptions,
 ) -> Option<Vec<TextRange>> {
     let node = unwrap_parenthesis(node)?;
 
     if let AnyJsExpression::JsConditionalExpression(node) = node {
-        let consequent =
-            handle_potential_react_component(node.consequent().ok()?, model, is_inside_jsx);
+        let consequent = handle_potential_react_component(
+            node.consequent().ok()?,
+            model,
+            is_inside_jsx,
+            options,
+        );
         let alternate =
-            handle_potential_react_component(node.alternate().ok()?, model, is_inside_jsx);
+            handle_potential_react_component(node.alternate().ok()?, model, is_inside_jsx, options);
 
         return match (consequent, alternate) {
             (Some(consequent), Some(alternate)) => Some([consequent, alternate].concat()),
@@ -261,24 +309,28 @@ fn handle_potential_react_component(
 
     if is_inside_jsx {
         if let Some(node) = ReactComponentExpression::cast(node.into_syntax()) {
-            let range = handle_react_component(node, model)?;
+            let range = handle_react_component(node, model, options)?;
             Some(range)
         } else {
             None
         }
     } else {
-        let range =
-            handle_react_component(ReactComponentExpression::cast(node.into_syntax())?, model)?;
+        let range = handle_react_component(
+            ReactComponentExpression::cast(node.into_syntax())?,
+            model,
+            options,
+        )?;
         Some(range)
     }
 }
 
 fn handle_react_component(
     node: ReactComponentExpression,
     model: &SemanticModel,
+    options: &UseJsxKeyInIterableOptions,
 ) -> Option<Vec<TextRange>> {
     match node {
-        ReactComponentExpression::JsxTagExpression(node) => handle_jsx_tag(&node, model),
+        ReactComponentExpression::JsxTagExpression(node) => handle_jsx_tag(&node, model, options),
         ReactComponentExpression::JsCallExpression(node) => {
             handle_react_non_jsx(&node, model).map(|r| vec![r])
         }
@@ -292,13 +344,21 @@ fn handle_react_component(
 /// ```jsx
 /// <Hello></Hello>
 /// ```
-fn handle_jsx_tag(node: &JsxTagExpression, model: &SemanticModel) -> Option<Vec<TextRange>> {
+fn handle_jsx_tag(
+    node: &JsxTagExpression,
+    model: &SemanticModel,
+    options: &UseJsxKeyInIterableOptions,
+) -> Option<Vec<TextRange>> {
     let tag = node.tag().ok()?;
     let tag = AnyJsxChild::cast(tag.into_syntax())?;
-    handle_jsx_child(&tag, model)
+    handle_jsx_child(&tag, model, options)
 }
 
-fn handle_jsx_child(node: &AnyJsxChild, model: &SemanticModel) -> Option<Vec<TextRange>> {
+fn handle_jsx_child(
+    node: &AnyJsxChild,
+    model: &SemanticModel,
+    options: &UseJsxKeyInIterableOptions,
+) -> Option<Vec<TextRange>> {
     let mut stack: Vec<AnyJsxChild> = vec![node.clone()];
     let mut ranges: Vec<TextRange> = vec![];
 
@@ -317,26 +377,16 @@ fn handle_jsx_child(node: &AnyJsxChild, model: &SemanticModel) -> Option<Vec<Tex
             }
             AnyJsxChild::JsxExpressionChild(node) => {
                 let expr = node.expression()?;
-                if let Some(child_ranges) = handle_potential_react_component(expr, model, true) {
+                if let Some(child_ranges) =
+                    handle_potential_react_component(expr, model, true, options)
+                {
                     ranges.extend(child_ranges);
                 }
             }
             AnyJsxChild::JsxFragment(node) => {
-                let has_any_tags = node.children().iter().any(|child| match &child {
-                    AnyJsxChild::JsxElement(_) | AnyJsxChild::JsxSelfClosingElement(_) => true,
-                    // HACK: don't flag the entire fragment if there's a conditional expression
-                    AnyJsxChild::JsxExpressionChild(node) => node
-                        .expression()
-                        .is_some_and(|n| n.as_js_conditional_expression().is_some()),
-                    _ => false,
-                });
-
-                if !has_any_tags {
-                    ranges.push(node.range());
-                    break;
+                if options.check_shorthand_fragments {
+                    ranges.push(node.range())
                 }
-
-                stack.extend(node.children());
             }
             _ => {}
         }

crates/biome_js_analyze/tests/specs/correctness/useJsxKeyInIterable/invalid.jsx

@@ -6,8 +6,6 @@ import React from "react";
 
 [<Hello />, xyz ? <Hello />: <Hello />, <Hello />];
 
-[<></>, <></>, <></>];
-
 data.map(x => <Hello>{x}</Hello>);
 
 data.map(x => <>{x}</>);
@@ -44,14 +42,6 @@ React.Children.map(c => React.cloneElement(c));
 	return item.condition ? <div /> : <div>foo</div>;
 });
 
-[].map((item) => {
-	return <><div /><div>{item}</div></>;
-});
-
-[].map((item) => {
-	return <>{item.condition ? <div /> : <div>foo</div>}</>;
-});
-
 [].map((item) => {
 	const x = 5;
 	const div = <div>{x}</div>;
@@ -63,3 +53,5 @@ React.Children.map(c => React.cloneElement(c));
 	const div = <div>{x}</div>;
 	return div;
 });
+
+data.map((item) => <React.Fragment><p>{item}</p></React.Fragment>)