feat(biome_js_analyze): implement noEqualsToNull rule (#8214)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

Author: Hiroki Okada

.changeset/legal-rice-clean.md

@@ -0,0 +1,19 @@
+---
+"@biomejs/biome": patch
+---
+
+Added the [`noEqualsToNull`](https://biomejs.dev/linter/rules/no-equals-to-null) rule, which enforces the use of `===` and `!==` for comparison with `null` instead of `==` or `!=`.
+
+**Invalid:**
+
+```js
+foo == null;
+foo != null;
+```
+
+**Valid:**
+
+```js
+foo === null;
+foo !== null;
+```

crates/biome_cli/src/execute/migrate/eslint_any_rule_to_biome.rs

@@ -169,6 +169,7 @@ define_categories! {
     "lint/nursery/noDeprecatedImports": "https://biomejs.dev/linter/rules/no-deprecated-imports",
     "lint/nursery/noDuplicateDependencies": "https://biomejs.dev/linter/rules/no-duplicate-dependencies",
     "lint/nursery/noEmptySource": "https://biomejs.dev/linter/rules/no-empty-source",
+    "lint/nursery/noEqualsToNull": "https://biomejs.dev/linter/rules/no-equals-to-null",
     "lint/nursery/noFloatingPromises": "https://biomejs.dev/linter/rules/no-floating-promises",
     "lint/nursery/noForIn": "https://biomejs.dev/linter/rules/no-for-in",
     "lint/nursery/noImplicitCoercion": "https://biomejs.dev/linter/rules/no-implicit-coercion",

crates/biome_configuration/src/analyzer/linter/rules.rs

@@ -6,6 +6,7 @@ use biome_analyze::declare_lint_group;
 pub mod no_continue;
 pub mod no_deprecated_imports;
 pub mod no_empty_source;
+pub mod no_equals_to_null;
 pub mod no_floating_promises;
 pub mod no_for_in;
 pub mod no_import_cycles;
@@ -41,4 +42,4 @@ pub mod use_sorted_classes;
 pub mod use_spread;
 pub mod use_vue_define_macros_order;
 pub mod use_vue_multi_word_component_names;
-declare_lint_group! { pub Nursery { name : "nursery" , rules : [self :: no_continue :: NoContinue , self :: no_deprecated_imports :: NoDeprecatedImports , self :: no_empty_source :: NoEmptySource , self :: no_floating_promises :: NoFloatingPromises , self :: no_for_in :: NoForIn , self :: no_import_cycles :: NoImportCycles , self :: no_increment_decrement :: NoIncrementDecrement , self :: no_jsx_literals :: NoJsxLiterals , self :: no_leaked_render :: NoLeakedRender , self :: no_misused_promises :: NoMisusedPromises , self :: no_next_async_client_component :: NoNextAsyncClientComponent , self :: no_parameters_only_used_in_recursion :: NoParametersOnlyUsedInRecursion , self :: no_react_forward_ref :: NoReactForwardRef , self :: no_shadow :: NoShadow , self :: no_sync_scripts :: NoSyncScripts , self :: no_ternary :: NoTernary , self :: no_unknown_attribute :: NoUnknownAttribute , self :: no_unnecessary_conditions :: NoUnnecessaryConditions , self :: no_unresolved_imports :: NoUnresolvedImports , self :: no_unused_expressions :: NoUnusedExpressions , self :: no_useless_catch_binding :: NoUselessCatchBinding , self :: no_useless_undefined :: NoUselessUndefined , self :: no_vue_data_object_declaration :: NoVueDataObjectDeclaration , self :: no_vue_duplicate_keys :: NoVueDuplicateKeys , self :: no_vue_reserved_keys :: NoVueReservedKeys , self :: no_vue_reserved_props :: NoVueReservedProps , self :: use_array_sort_compare :: UseArraySortCompare , self :: use_consistent_arrow_return :: UseConsistentArrowReturn , self :: use_exhaustive_switch_cases :: UseExhaustiveSwitchCases , self :: use_explicit_type :: UseExplicitType , self :: use_find :: UseFind , self :: use_max_params :: UseMaxParams , self :: use_qwik_method_usage :: UseQwikMethodUsage , self :: use_qwik_valid_lexical_scope :: UseQwikValidLexicalScope , self :: use_sorted_classes :: UseSortedClasses , self :: use_spread :: UseSpread , self :: use_vue_define_macros_order :: UseVueDefineMacrosOrder , self :: use_vue_multi_word_component_names :: UseVueMultiWordComponentNames ,] } }
+declare_lint_group! { pub Nursery { name : "nursery" , rules : [self :: no_continue :: NoContinue , self :: no_deprecated_imports :: NoDeprecatedImports , self :: no_empty_source :: NoEmptySource , self :: no_equals_to_null :: NoEqualsToNull , self :: no_floating_promises :: NoFloatingPromises , self :: no_for_in :: NoForIn , self :: no_import_cycles :: NoImportCycles , self :: no_increment_decrement :: NoIncrementDecrement , self :: no_jsx_literals :: NoJsxLiterals , self :: no_leaked_render :: NoLeakedRender , self :: no_misused_promises :: NoMisusedPromises , self :: no_next_async_client_component :: NoNextAsyncClientComponent , self :: no_parameters_only_used_in_recursion :: NoParametersOnlyUsedInRecursion , self :: no_react_forward_ref :: NoReactForwardRef , self :: no_shadow :: NoShadow , self :: no_sync_scripts :: NoSyncScripts , self :: no_ternary :: NoTernary , self :: no_unknown_attribute :: NoUnknownAttribute , self :: no_unnecessary_conditions :: NoUnnecessaryConditions , self :: no_unresolved_imports :: NoUnresolvedImports , self :: no_unused_expressions :: NoUnusedExpressions , self :: no_useless_catch_binding :: NoUselessCatchBinding , self :: no_useless_undefined :: NoUselessUndefined , self :: no_vue_data_object_declaration :: NoVueDataObjectDeclaration , self :: no_vue_duplicate_keys :: NoVueDuplicateKeys , self :: no_vue_reserved_keys :: NoVueReservedKeys , self :: no_vue_reserved_props :: NoVueReservedProps , self :: use_array_sort_compare :: UseArraySortCompare , self :: use_consistent_arrow_return :: UseConsistentArrowReturn , self :: use_exhaustive_switch_cases :: UseExhaustiveSwitchCases , self :: use_explicit_type :: UseExplicitType , self :: use_find :: UseFind , self :: use_max_params :: UseMaxParams , self :: use_qwik_method_usage :: UseQwikMethodUsage , self :: use_qwik_valid_lexical_scope :: UseQwikValidLexicalScope , self :: use_sorted_classes :: UseSortedClasses , self :: use_spread :: UseSpread , self :: use_vue_define_macros_order :: UseVueDefineMacrosOrder , self :: use_vue_multi_word_component_names :: UseVueMultiWordComponentNames ,] } }

crates/biome_diagnostics_categories/src/categories.rs

@@ -0,0 +1,106 @@
+use crate::JsRuleAction;
+use biome_analyze::{
+    Ast, FixKind, Rule, RuleDiagnostic, RuleSource, context::RuleContext, declare_lint_rule,
+};
+use biome_console::markup;
+use biome_diagnostics::Severity;
+use biome_js_factory::make;
+use biome_js_syntax::{
+    AnyJsExpression, AnyJsLiteralExpression, JsBinaryExpression,
+    JsSyntaxKind::{EQ2, NEQ},
+    JsSyntaxToken, T,
+};
+use biome_rowan::{BatchMutationExt, SyntaxResult};
+use biome_rule_options::no_equals_to_null::NoEqualsToNullOptions;
+
+declare_lint_rule! {
+    /// Require the use of `===` or `!==` for comparison with `null`.
+    ///
+    /// Comparing to `null` with `==` or `!=` may have unintended results as the
+    /// expression evaluates to `true` when comparing `null` to `undefined`.
+    ///
+    /// ## Examples
+    ///
+    /// ### Invalid
+    ///
+    /// ```js,expect_diagnostic
+    /// foo == null;
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// foo != null;
+    /// ```
+    ///
+    /// ### Valid
+    ///
+    /// ```js
+    /// foo === null;
+    /// ```
+    ///
+    /// ```js
+    /// foo !== null;
+    /// ```
+    pub NoEqualsToNull {
+        version: "next",
+        name: "noEqualsToNull",
+        language: "js",
+        sources: &[RuleSource::Eslint("no-eq-null").same()],
+        recommended: false,
+        severity: Severity::Error,
+        fix_kind: FixKind::Unsafe,
+    }
+}
+
+impl Rule for NoEqualsToNull {
+    type Query = Ast<JsBinaryExpression>;
+    type State = JsSyntaxToken;
+    type Signals = Option<Self::State>;
+    type Options = NoEqualsToNullOptions;
+
+    fn run(ctx: &RuleContext<Self>) -> Self::Signals {
+        let node = ctx.query();
+        let op = node.operator_token().ok()?;
+
+        if matches!(op.kind(), EQ2 | NEQ)
+            && (is_null_literal(&node.left()) || is_null_literal(&node.right()))
+        {
+            return Some(op);
+        }
+
+        None
+    }
+
+    fn diagnostic(_ctx: &RuleContext<Self>, op: &Self::State) -> Option<RuleDiagnostic> {
+        let text_trimmed = op.text_trimmed();
+        Some(RuleDiagnostic::new(
+            rule_category!(),
+            op.text_trimmed_range(),
+            markup! {
+                ""<Emphasis>"null"</Emphasis>" comparison with "<Emphasis>{text_trimmed}</Emphasis>" is disallowed."
+            },
+        ))
+    }
+
+    fn action(ctx: &RuleContext<Self>, op: &Self::State) -> Option<JsRuleAction> {
+        let mut mutation = ctx.root().begin();
+
+        let suggestion = if op.kind() == EQ2 { T![===] } else { T![!==] };
+        mutation.replace_token(op.clone(), make::token(suggestion));
+
+        Some(JsRuleAction::new(
+            ctx.metadata().action_category(ctx.category(), ctx.group()),
+            ctx.metadata().applicability(),
+            markup! { "Use "<Emphasis>{suggestion.to_string()?}</Emphasis>" instead." }.to_owned(),
+            mutation,
+        ))
+    }
+}
+
+fn is_null_literal(res: &SyntaxResult<AnyJsExpression>) -> bool {
+    matches!(
+        res,
+        Ok(AnyJsExpression::AnyJsLiteralExpression(
+            AnyJsLiteralExpression::JsNullLiteralExpression(_)
+        ))
+    )
+}

crates/biome_js_analyze/src/lint/nursery.rs

@@ -0,0 +1,3 @@
+/* should generate diagnostics */
+foo == null;
+foo != null;

crates/biome_js_analyze/src/lint/nursery/no_equals_to_null.rs

@@ -0,0 +1,48 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: invalid.js
+---
+# Input
+```js
+/* should generate diagnostics */
+foo == null;
+foo != null;
+
+```
+
+# Diagnostics
+```
+invalid.js:2:5 lint/nursery/noEqualsToNull  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  × null comparison with == is disallowed.
+  
+    1 │ /* should generate diagnostics */
+  > 2 │ foo == null;
+      │     ^^
+    3 │ foo != null;
+    4 │ 
+  
+  i Unsafe fix: Use === instead.
+  
+    2 │ foo·===·null;
+      │       +      
+
+```
+
+```
+invalid.js:3:5 lint/nursery/noEqualsToNull  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  × null comparison with != is disallowed.
+  
+    1 │ /* should generate diagnostics */
+    2 │ foo == null;
+  > 3 │ foo != null;
+      │     ^^
+    4 │ 
+  
+  i Unsafe fix: Use !== instead.
+  
+    3 │ foo·!==·null;
+      │       +      
+
+```

crates/biome_js_analyze/tests/specs/nursery/noEqualsToNull/invalid.js

@@ -0,0 +1,3 @@
+/* should not generate diagnostics */
+foo === null;
+foo !== null;

crates/biome_js_analyze/tests/specs/nursery/noEqualsToNull/invalid.js.snap

@@ -0,0 +1,11 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: valid.js
+---
+# Input
+```js
+/* should not generate diagnostics */
+foo === null;
+foo !== null;
+
+```