Add lint rule for calling init() after creation.

lib/widgets/app_text_field.dart

@@ -13,18 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-import 'dart:async';
-
 import 'package:flutter/material.dart';
 
 import 'app_input_decoration.dart';
 
 /// TextField without autocorrect and suggestions
-// ignore: must_be_immutable
 class AppTextField extends TextField {
-  bool _initialized = false;
-  AppTextField({
+  const AppTextField({
     // default settings to turn off autocorrect
     super.autocorrect = false,
     super.enableSuggestions = false,
@@ -89,22 +84,14 @@ class AppTextField extends TextField {
     super.canRequestFocus,
     super.spellCheckConfiguration,
     super.magnifierConfiguration,
-  }) : super(decoration: decoration) {
-    // TODO: Replace this with a custom lint check, if possible
-    Timer.run(() {
-      assert(_initialized, 'AppTextField not initialized!');
-    });
-  }
+  }) : super(decoration: decoration);
 
-  Widget init() {
-    _initialized = true;
-    return Builder(
-      builder: (context) => DefaultSelectionStyle(
-        selectionColor: decoration?.errorText != null
-            ? Theme.of(context).colorScheme.error
-            : null,
-        child: this,
-      ),
-    );
-  }
+  Widget init() => Builder(
+        builder: (context) => DefaultSelectionStyle(
+          selectionColor: decoration?.errorText != null
+              ? Theme.of(context).colorScheme.error
+              : null,
+          child: this,
+        ),
+      );
 }

lib/widgets/app_text_form_field.dart

@@ -14,17 +14,13 @@
  * limitations under the License.
  */
 
-import 'dart:async';
-
 import 'package:flutter/material.dart';
 
 import 'app_input_decoration.dart';
 
 /// TextFormField without autocorrect and suggestions
-// ignore: must_be_immutable
 class AppTextFormField extends TextFormField {
   final AppInputDecoration? decoration;
-  bool _initialized = false;
   AppTextFormField({
     // default settings to turn off autocorrect
     super.autocorrect = false,
@@ -94,22 +90,14 @@ class AppTextFormField extends TextFormField {
     super.clipBehavior,
     super.scribbleEnabled,
     super.canRequestFocus,
-  }) : super(decoration: decoration) {
-    // TODO: Replace this with a custom lint check, if possible
-    Timer.run(() {
-      assert(_initialized, 'AppTextFormField not initialized!');
-    });
-  }
+  }) : super(decoration: decoration);
 
-  Widget init() {
-    _initialized = true;
-    return Builder(
-      builder: (context) => DefaultSelectionStyle(
-        selectionColor: decoration?.errorText != null
-            ? Theme.of(context).colorScheme.error
-            : null,
-        child: this,
-      ),
-    );
-  }
+  Widget init() => Builder(
+        builder: (context) => DefaultSelectionStyle(
+          selectionColor: decoration?.errorText != null
+              ? Theme.of(context).colorScheme.error
+              : null,
+          child: this,
+        ),
+      );
 }

lint/lib/lint.dart

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:custom_lint_builder/custom_lint_builder.dart';
 
@@ -30,6 +31,8 @@ class _AppLinter extends PluginBase {
           discouraged: 'TextFormField',
           recommended: 'AppTextFormField',
         ),
+        const CallInitAfterCreation(className: 'AppTextField'),
+        const CallInitAfterCreation(className: 'AppTextFormField'),
       ];
 }
 
@@ -59,3 +62,35 @@ class UseRecommendedWidget extends DartLintRule {
     });
   }
 }
+
+class CallInitAfterCreation extends DartLintRule {
+  final String className;
+
+  const CallInitAfterCreation({required this.className})
+      : super(
+            code: const LintCode(
+          name: 'call_init_after_creation',
+          problemMessage: 'Call init() after creation',
+        ));
+
+  @override
+  void run(
+    CustomLintResolver resolver,
+    ErrorReporter reporter,
+    CustomLintContext context,
+  ) {
+    context.registry.addInstanceCreationExpression((node) {
+      if (node.constructorName.toString() == className) {
+        final dot = node.endToken.next;
+        final next = dot?.next;
+        if (dot?.type == TokenType.PERIOD) {
+          if (next?.type == TokenType.IDENTIFIER &&
+              next?.toString() == 'init') {
+            return;
+          }
+        }
+        reporter.reportErrorForNode(code, node.constructorName);
+      }
+    });
+  }
+}