test: Add test cases for special attribute in DomValidator

Add test cases to verify DomValidator accepts attribute:
- ':' prefix for binding attributes (e.g. :class)
- '@' prefix for event handlers (e.g. @scroll.window)

packages/jaspr/test/server/dom_validator_test.dart

@@ -0,0 +1,92 @@
+import 'package:jaspr/src/server/markup_render_object.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('DomValidator', () {
+    late DomValidator validator;
+
+    setUp(() {
+      validator = DomValidator();
+    });
+
+    group('validateElementName', () {
+      test('accepts valid element names', () {
+        expect(() => validator.validateElementName('div'), returnsNormally);
+        expect(() => validator.validateElementName('custom-element'),
+            returnsNormally);
+        expect(() => validator.validateElementName('h1'), returnsNormally);
+      });
+
+      test('throws on invalid element names', () {
+        expect(
+            () => validator.validateElementName('1div'), throwsArgumentError);
+        expect(() => validator.validateElementName('-element'),
+            throwsArgumentError);
+        expect(
+            () => validator.validateElementName('div!'), throwsArgumentError);
+      });
+    });
+
+    group('validateAttributeName', () {
+      test('accepts valid attribute names', () {
+        expect(() => validator.validateAttributeName('id'), returnsNormally);
+        expect(() => validator.validateAttributeName('data-test'),
+            returnsNormally);
+        expect(() => validator.validateAttributeName('aria-label'),
+            returnsNormally);
+        expect(
+            () => validator.validateAttributeName(':class'), returnsNormally);
+        expect(() => validator.validateAttributeName('@scroll.window'),
+            returnsNormally);
+      });
+
+      test('throws on invalid attribute names', () {
+        expect(
+            () => validator.validateAttributeName('1id'), throwsArgumentError);
+        expect(() => validator.validateAttributeName('-test'),
+            throwsArgumentError);
+        expect(() => validator.validateAttributeName('data!'),
+            throwsArgumentError);
+      });
+    });
+
+    group('isSelfClosing', () {
+      test('returns true for self-closing elements', () {
+        expect(validator.isSelfClosing('img'), isTrue);
+        expect(validator.isSelfClosing('br'), isTrue);
+        expect(validator.isSelfClosing('input'), isTrue);
+      });
+
+      test('returns false for non-self-closing elements', () {
+        expect(validator.isSelfClosing('div'), isFalse);
+        expect(validator.isSelfClosing('span'), isFalse);
+        expect(validator.isSelfClosing('p'), isFalse);
+      });
+    });
+
+    group('hasStrictWhitespace', () {
+      test('returns true for elements with strict whitespace', () {
+        expect(validator.hasStrictWhitespace('p'), isTrue);
+        expect(validator.hasStrictWhitespace('h1'), isTrue);
+        expect(validator.hasStrictWhitespace('label'), isTrue);
+      });
+
+      test('returns false for elements without strict whitespace', () {
+        expect(validator.hasStrictWhitespace('div'), isFalse);
+        expect(validator.hasStrictWhitespace('span'), isFalse);
+      });
+    });
+
+    group('hasStrictFormatting', () {
+      test('returns true for elements with strict formatting', () {
+        expect(validator.hasStrictFormatting('pre'), isTrue);
+        expect(validator.hasStrictFormatting('span'), isTrue);
+      });
+
+      test('returns false for elements without strict formatting', () {
+        expect(validator.hasStrictFormatting('div'), isFalse);
+        expect(validator.hasStrictFormatting('p'), isFalse);
+      });
+    });
+  });
+}