biomejs · ematipico · Aug 5, 2025 · Aug 1, 2025 · Aug 5, 2025 · Aug 5, 2025
diff --git a/.changeset/cold-seals-ring.md b/.changeset/cold-seals-ring.md
@@ -0,0 +1,23 @@
+---
+"@biomejs/biome": patch
+---
+
+Added the new nursery rule `noUnnecessararyConditions`, which detects whenever some conditions don't
+change during the life cycle of the program, and truthy or false, hence deemed redundant.
+
+For example, the following snippets will trigger the rule:
+
+```js
+// Always truthy literal conditions
+if (true) {
+  console.log("always runs");
+}
+```
+
+```ts
+// Unnecessary condition on constrained string type
+function foo(arg: 'bar' | 'baz') {
+  if (arg) {  // This check is unnecessary
+  }
+}
+```
diff --git a/crates/biome_cli/src/execute/migrate/eslint_any_rule_to_biome.rs b/crates/biome_cli/src/execute/migrate/eslint_any_rule_to_biome.rs
diff --git a/crates/biome_configuration/src/analyzer/linter/rules.rs b/crates/biome_configuration/src/analyzer/linter/rules.rs
diff --git a/crates/biome_css_analyze/tests/spec_tests.rs b/crates/biome_css_analyze/tests/spec_tests.rs
@@ -173,7 +173,7 @@ pub(crate) fn analyze_and_snap(
         "css",
     );
 
-    assert_diagnostics_expectation_comment(input_file, root.syntax(), diagnostics.len());
+    assert_diagnostics_expectation_comment(input_file, root.syntax(), diagnostics);
 }
 
 fn check_code_action(

diff --git a/crates/biome_diagnostics_categories/src/categories.rs b/crates/biome_diagnostics_categories/src/categories.rs
@@ -189,6 +189,7 @@ define_categories! {
     "lint/nursery/noUnknownSelectorPseudoElement": "https://biomejs.dev/linter/rules/no-unknown-selector-pseudo-element",
     "lint/nursery/noUnknownUnit": "https://biomejs.dev/linter/rules/no-unknown-unit",
     "lint/nursery/noUnmatchableAnbSelector": "https://biomejs.dev/linter/rules/no-unmatchable-anb-selector",
+    "lint/nursery/noUnnecessaryConditions": "https://biomejs.dev/linter/rules/no-unnecessary-conditions",
     "lint/nursery/noUnresolvedImports": "https://biomejs.dev/linter/rules/no-unresolved-imports",
     "lint/nursery/noUnusedFunctionParameters": "https://biomejs.dev/linter/rules/no-unused-function-parameters",
     "lint/nursery/noUnwantedPolyfillio": "https://biomejs.dev/linter/rules/no-unwanted-polyfillio",

diff --git a/crates/biome_graphql_analyze/tests/spec_tests.rs b/crates/biome_graphql_analyze/tests/spec_tests.rs
@@ -145,7 +145,7 @@ pub(crate) fn analyze_and_snap(
         "graphql",
     );
 
-    assert_diagnostics_expectation_comment(input_file, root.syntax(), diagnostics.len());
+    assert_diagnostics_expectation_comment(input_file, root.syntax(), diagnostics);
 }
 
 fn check_code_action(

diff --git a/crates/biome_js_analyze/src/lint/nursery.rs b/crates/biome_js_analyze/src/lint/nursery.rs
@@ -25,6 +25,7 @@ pub mod no_secrets;
 pub mod no_shadow;
 pub mod no_ts_ignore;
 pub mod no_unassigned_variables;
+pub mod no_unnecessary_conditions;
 pub mod no_unresolved_imports;
 pub mod no_unwanted_polyfillio;
 pub mod no_useless_backref_in_regex;
@@ -57,4 +58,4 @@ pub mod use_sorted_classes;
 pub mod use_symbol_description;
 pub mod use_unified_type_signature;
 pub mod use_unique_element_ids;
-declare_lint_group! { pub Nursery { name : "nursery" , rules : [self :: no_await_in_loop :: NoAwaitInLoop , self :: no_bitwise_operators :: NoBitwiseOperators , self :: no_constant_binary_expression :: NoConstantBinaryExpression , self :: no_destructured_props :: NoDestructuredProps , self :: no_excessive_lines_per_function :: NoExcessiveLinesPerFunction , self :: no_floating_promises :: NoFloatingPromises , self :: no_global_dirname_filename :: NoGlobalDirnameFilename , self :: no_implicit_coercion :: NoImplicitCoercion , self :: no_import_cycles :: NoImportCycles , self :: no_magic_numbers :: NoMagicNumbers , self :: no_misused_promises :: NoMisusedPromises , self :: no_nested_component_definitions :: NoNestedComponentDefinitions , self :: no_non_null_asserted_optional_chain :: NoNonNullAssertedOptionalChain , self :: no_noninteractive_element_interactions :: NoNoninteractiveElementInteractions , self :: no_process_global :: NoProcessGlobal , self :: no_qwik_use_visible_task :: NoQwikUseVisibleTask , self :: no_react_prop_assign :: NoReactPropAssign , self :: no_restricted_elements :: NoRestrictedElements , self :: no_secrets :: NoSecrets , self :: no_shadow :: NoShadow , self :: no_ts_ignore :: NoTsIgnore , self :: no_unassigned_variables :: NoUnassignedVariables , self :: no_unresolved_imports :: NoUnresolvedImports , self :: no_unwanted_polyfillio :: NoUnwantedPolyfillio , self :: no_useless_backref_in_regex :: NoUselessBackrefInRegex , self :: no_useless_escape_in_string :: NoUselessEscapeInString , self :: no_useless_undefined :: NoUselessUndefined , self :: no_vue_reserved_keys :: NoVueReservedKeys , self :: no_vue_reserved_props :: NoVueReservedProps , self :: use_adjacent_getter_setter :: UseAdjacentGetterSetter , self :: use_anchor_href :: UseAnchorHref , self :: use_consistent_object_definition :: UseConsistentObjectDefinition , self :: use_consistent_response :: UseConsistentResponse , self :: use_consistent_type_definitions :: UseConsistentTypeDefinitions , self :: use_exhaustive_switch_cases :: UseExhaustiveSwitchCases , self :: use_explicit_type :: UseExplicitType , self :: use_exports_last :: UseExportsLast , self :: use_for_component :: UseForComponent , self :: use_google_font_preconnect :: UseGoogleFontPreconnect , self :: use_image_size :: UseImageSize , self :: use_index_of :: UseIndexOf , self :: use_iterable_callback_return :: UseIterableCallbackReturn , self :: use_json_import_attribute :: UseJsonImportAttribute , self :: use_numeric_separators :: UseNumericSeparators , self :: use_object_spread :: UseObjectSpread , self :: use_parse_int_radix :: UseParseIntRadix , self :: use_qwik_classlist :: UseQwikClasslist , self :: use_react_function_components :: UseReactFunctionComponents , self :: use_readonly_class_properties :: UseReadonlyClassProperties , self :: use_single_js_doc_asterisk :: UseSingleJsDocAsterisk , self :: use_sorted_classes :: UseSortedClasses , self :: use_symbol_description :: UseSymbolDescription , self :: use_unified_type_signature :: UseUnifiedTypeSignature , self :: use_unique_element_ids :: UseUniqueElementIds ,] } }
+declare_lint_group! { pub Nursery { name : "nursery" , rules : [self :: no_await_in_loop :: NoAwaitInLoop , self :: no_bitwise_operators :: NoBitwiseOperators , self :: no_constant_binary_expression :: NoConstantBinaryExpression , self :: no_destructured_props :: NoDestructuredProps , self :: no_excessive_lines_per_function :: NoExcessiveLinesPerFunction , self :: no_floating_promises :: NoFloatingPromises , self :: no_global_dirname_filename :: NoGlobalDirnameFilename , self :: no_implicit_coercion :: NoImplicitCoercion , self :: no_import_cycles :: NoImportCycles , self :: no_magic_numbers :: NoMagicNumbers , self :: no_misused_promises :: NoMisusedPromises , self :: no_nested_component_definitions :: NoNestedComponentDefinitions , self :: no_non_null_asserted_optional_chain :: NoNonNullAssertedOptionalChain , self :: no_noninteractive_element_interactions :: NoNoninteractiveElementInteractions , self :: no_process_global :: NoProcessGlobal , self :: no_qwik_use_visible_task :: NoQwikUseVisibleTask , self :: no_react_prop_assign :: NoReactPropAssign , self :: no_restricted_elements :: NoRestrictedElements , self :: no_secrets :: NoSecrets , self :: no_shadow :: NoShadow , self :: no_ts_ignore :: NoTsIgnore , self :: no_unassigned_variables :: NoUnassignedVariables , self :: no_unnecessary_conditions :: NoUnnecessaryConditions , self :: no_unresolved_imports :: NoUnresolvedImports , self :: no_unwanted_polyfillio :: NoUnwantedPolyfillio , self :: no_useless_backref_in_regex :: NoUselessBackrefInRegex , self :: no_useless_escape_in_string :: NoUselessEscapeInString , self :: no_useless_undefined :: NoUselessUndefined , self :: no_vue_reserved_keys :: NoVueReservedKeys , self :: no_vue_reserved_props :: NoVueReservedProps , self :: use_adjacent_getter_setter :: UseAdjacentGetterSetter , self :: use_anchor_href :: UseAnchorHref , self :: use_consistent_object_definition :: UseConsistentObjectDefinition , self :: use_consistent_response :: UseConsistentResponse , self :: use_consistent_type_definitions :: UseConsistentTypeDefinitions , self :: use_exhaustive_switch_cases :: UseExhaustiveSwitchCases , self :: use_explicit_type :: UseExplicitType , self :: use_exports_last :: UseExportsLast , self :: use_for_component :: UseForComponent , self :: use_google_font_preconnect :: UseGoogleFontPreconnect , self :: use_image_size :: UseImageSize , self :: use_index_of :: UseIndexOf , self :: use_iterable_callback_return :: UseIterableCallbackReturn , self :: use_json_import_attribute :: UseJsonImportAttribute , self :: use_numeric_separators :: UseNumericSeparators , self :: use_object_spread :: UseObjectSpread , self :: use_parse_int_radix :: UseParseIntRadix , self :: use_qwik_classlist :: UseQwikClasslist , self :: use_react_function_components :: UseReactFunctionComponents , self :: use_readonly_class_properties :: UseReadonlyClassProperties , self :: use_single_js_doc_asterisk :: UseSingleJsDocAsterisk , self :: use_sorted_classes :: UseSortedClasses , self :: use_symbol_description :: UseSymbolDescription , self :: use_unified_type_signature :: UseUnifiedTypeSignature , self :: use_unique_element_ids :: UseUniqueElementIds ,] } }
-Original file line number
+Diff line change
@@ Expand Up / @@ -173,7 +173,7 @@ pub(crate) fn analyze_and_snap( @@
             "css",
         );
-        assert_diagnostics_expectation_comment(input_file, root.syntax(), diagnostics.len());
+        assert_diagnostics_expectation_comment(input_file, root.syntax(), diagnostics);
     }
     fn check_code_action(
@@ Expand Down @@