Fixed avoid_unused_parameters

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Added `avoid_using_debug_print` rule
 - Fixed an issue with no_magic_number lint
+- Fixed `avoid_unused_parameters` lint's bug regarding function variable assignment/declaration 
 
 ## 0.1.4
 

lib/src/lints/avoid_unused_parameters/avoid_unused_parameters_rule.dart

@@ -9,6 +9,11 @@ import 'package:solid_lints/src/models/solid_lint_rule.dart';
 /// ### Example:
 /// #### BAD:
 /// ```dart
+/// typedef MaxFun = int Function(int a, int b);
+/// final MaxFun bad = (int a, int b) => 1; // LINT
+/// final MaxFun testFun = (int a, int b) { // LINT
+///   return 4;
+/// };
 /// void fun(String x) {} // LINT
 /// void fun2(String x, String y) { // LINT
 ///   print(y);
@@ -27,6 +32,11 @@ import 'package:solid_lints/src/models/solid_lint_rule.dart';
 ///
 /// #### GOOD:
 /// ```dart
+/// typedef MaxFun = int Function(int a, int b);
+/// final MaxFun good = (int a, int b) => a + b;
+/// final MaxFun testFun = (int a, int b) {
+///   return a + b;
+/// };
 /// void fun(String _) {} // Replacing with underscores silences the warning
 /// void fun2(String _, String y) {
 ///   print(y);

lib/src/lints/avoid_unused_parameters/avoid_unused_parameters_visitor.dart

@@ -85,20 +85,17 @@ class AvoidUnusedParametersVisitor extends RecursiveAstVisitor<void> {
   }
 
   @override
-  void visitFunctionDeclaration(FunctionDeclaration node) {
-    super.visitFunctionDeclaration(node);
-
-    final parameters = node.functionExpression.parameters;
-
-    if (node.externalKeyword != null ||
-        (parameters == null || parameters.parameters.isEmpty)) {
+  void visitFunctionExpression(FunctionExpression node) {
+    super.visitFunctionExpression(node);
+    final params = node.parameters;
+    if (params == null) {
       return;
     }
 
     _unusedParameters.addAll(
       _getUnusedParameters(
-        node.functionExpression.body,
-        parameters.parameters,
+        node.body,
+        params.parameters,
       ).whereNot(nameConsistsOfUnderscoresOnly),
     );
   }

lint_test/avoid_unused_parameters_test.dart

@@ -1,4 +1,4 @@
-// ignore_for_file: prefer_const_declarations, prefer_match_file_name
+// ignore_for_file: prefer_const_declarations, prefer_match_file_name, avoid_global_state
 // ignore_for_file: unnecessary_nullable_for_final_variable_declarations
 // ignore_for_file: unused_local_variable
 // ignore_for_file: unused_element
@@ -10,11 +10,70 @@ import 'package:flutter/material.dart';
 
 /// Check the `avoid_unused_parameters` rule
 
+typedef MaxFun = int Function(int a, int b);
+
+typedef Named = String Function({required String text});
+
+// expect_lint: avoid_unused_parameters
+final MaxFun bad = (int a, int b) => 1;
+
+final MaxFun good = (int a, _) => a;
+
+final MaxFun ok = (int _, int __) => 1;
+
+final MaxFun goodMax = (int a, int b) {
+  return a + b;
+};
+
+// expect_lint: avoid_unused_parameters
+final Named _named = ({required text}) {
+  return '';
+};
+
+final Named _named2 = ({required text}) {
+  return text;
+};
+
+// expect_lint: avoid_unused_parameters
+final Named _named3 = ({required text}) => '';
+
+final Named _named4 = ({required text}) => text;
+
+// expect_lint: avoid_unused_parameters
+final optional = (int a, [int b = 0]) {
+  return a;
+};
+
+// expect_lint: avoid_unused_parameters
+final named = (int a, {required int b, int c = 0}) {
+  return a + c;
+};
+
+// good
+var k = (String g) {
+  return g;
+};
+
+// expect_lint: avoid_unused_parameters
+var c = (String g) {
+  return '0';
+};
+
+// expect_lint: avoid_unused_parameters
+final MaxFun tetsFun = (int a, int b) {
+  return 4;
+};
+
 // expect_lint: avoid_unused_parameters
 void fun(String s) {
   return;
 }
 
+// expect_lint: avoid_unused_parameters
+void fun2(String s) {
+  return;
+}
+
 class TestClass {
   // expect_lint: avoid_unused_parameters
   static void staticMethod(int a) {}
@@ -34,6 +93,14 @@ class TestClass2 {
 }
 
 class SomeOtherClass {
+  // expect_lint: avoid_unused_parameters
+  final MaxFun maxFunLint = (int a, int b) => 1;
+
+  // Good
+  final MaxFun good = (int a, int b) {
+    return a * b;
+  };
+
   // expect_lint: avoid_unused_parameters
   void method(String s) {
     return;
@@ -67,11 +134,11 @@ void closure(int a) {
   }
 }
 
-typedef MaxFun = int Function(int a, int b);
-
-// Allowed same way as override
+// expect_lint: avoid_unused_parameters
 final MaxFun maxFunInstance = (int a, int b) => 1;
 
+final MaxFun m = (_, __) => 1;
+
 class Foo {
   final int a;
   final int? b;