migrate prefer early return rule with tests

lib/src/lints/prefer_early_return/prefer_early_return_rule.dart

@@ -32,23 +32,20 @@ import 'package:solid_lints/src/lints/prefer_early_return/visitors/prefer_early_
 /// }
 /// ```
 class PreferEarlyReturnRule extends AnalysisRule {
-  /// The name of the lint
+  /// Lint name
   static const String lintName = 'prefer_early_return';
 
-  /// The message shown when the lint is triggered
-  static const String lintMessage = 'Use reverse if to reduce nesting';
-
   /// Lint code
   static const LintCode _code = LintCode(
     lintName,
-    lintMessage,
+    "Use reverse if to reduce nesting",
   );
 
-  /// Creates a new instance of [PreferEarlyReturnRule]
+  /// Creates an instance of [PreferEarlyReturnRule]
   PreferEarlyReturnRule()
       : super(
           name: lintName,
-          description: lintMessage,
+          description: 'Use reverse if to reduce nesting',
         );
 
   @override
@@ -59,7 +56,11 @@ class PreferEarlyReturnRule extends AnalysisRule {
     RuleVisitorRegistry registry,
     RuleContext context,
   ) {
-    final visitor = PreferEarlyReturnVisitor(this);
+    final visitor = PreferEarlyReturnVisitor(
+      rule: this,
+      context: context,
+    );
+
     registry.addBlockFunctionBody(this, visitor);
   }
 }

lib/src/lints/prefer_early_return/visitors/prefer_early_return_visitor.dart

@@ -1,3 +1,4 @@
+import 'package:analyzer/analysis_rule/rule_context.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:solid_lints/src/lints/prefer_early_return/prefer_early_return_rule.dart';
@@ -6,19 +7,27 @@ import 'package:solid_lints/src/lints/prefer_early_return/visitors/throw_express
 
 /// Visitor for [PreferEarlyReturnRule].
 class PreferEarlyReturnVisitor extends RecursiveAstVisitor<void> {
-  /// The rule associated with this visitor.
+  /// The rule associated with the visitor.
   final PreferEarlyReturnRule rule;
 
-  /// Creates an instance of [PreferEarlyReturnVisitor].
-  PreferEarlyReturnVisitor(this.rule);
+  /// The context associated with the visitor.
+  final RuleContext context;
+
+  /// Constructor for [PreferEarlyReturnVisitor].
+  PreferEarlyReturnVisitor({
+    required this.rule,
+    required this.context,
+  });
 
   @override
   void visitBlockFunctionBody(BlockFunctionBody node) {
     super.visitBlockFunctionBody(node);
 
     if (node.block.statements.isEmpty) return;
 
-    final (ifStatements, nextStatement) = _getStartIfStatements(node);
+    final (ifStatements, nextStatement) = _getIfStatementsAndNextStatement(
+      node,
+    );
     if (ifStatements.isEmpty) return;
 
     // limit visitor to only work with functions
@@ -29,25 +38,24 @@ class PreferEarlyReturnVisitor extends RecursiveAstVisitor<void> {
 
     if (!nextStatementIsEmptyReturn && !nextStatementIsNull) return;
 
-    _handleIfStatement(ifStatements.last);
-  }
+    final lastIf = ifStatements.last;
 
-  void _handleIfStatement(IfStatement node) {
-    if (_isElseIfStatement(node)) return;
-    if (_hasElseStatement(node)) return;
-    if (_hasReturnStatement(node)) return;
-    if (_hasThrowExpression(node)) return;
+    if (lastIf case IfStatement(elseStatement: Statement())) return;
+    if (_hasReturnStatement(lastIf) || _hasThrowExpression(lastIf)) return;
 
-    rule.reportAtNode(node);
+    context.currentUnit?.diagnosticReporter.atNode(
+      lastIf,
+      rule.diagnosticCode,
+    );
   }
 
-// returns a list of if statements at the start of the function
-// and the next statement after it
-// examples:
-// [if, if, if, return] -> ([if, if, if], return)
-// [if, if, if, _doSomething, return] -> ([if, if, if], _doSomething)
-// [if, if, if] -> ([if, if, if], null)
-  (List<IfStatement>, Statement?) _getStartIfStatements(
+  // returns a list of if statements at the start of the function
+  // and the next statement after it
+  // examples:
+  // [if, if, if, return] -> ([if, if, if], return)
+  // [if, if, if, _doSomething, return] -> ([if, if, if], _doSomething)
+  // [if, if, if] -> ([if, if, if], null)
+  (List<IfStatement>, Statement?) _getIfStatementsAndNextStatement(
     BlockFunctionBody body,
   ) {
     final List<IfStatement> ifStatements = [];
@@ -58,15 +66,8 @@ class PreferEarlyReturnVisitor extends RecursiveAstVisitor<void> {
         return (ifStatements, statement);
       }
     }
-    return (ifStatements, null);
-  }
 
-  bool _hasElseStatement(IfStatement node) {
-    return node.elseStatement != null;
-  }
-
-  bool _isElseIfStatement(IfStatement node) {
-    return node.elseStatement != null && node.elseStatement is IfStatement;
+    return (ifStatements, null);
   }
 
   bool _hasReturnStatement(Statement node) {