Move prefer_double_quotes tests

test/rules/all.dart

@@ -100,6 +100,7 @@ import 'prefer_const_literals_to_create_immutables_test.dart'
 import 'prefer_constructors_over_static_methods_test.dart'
     as prefer_constructors_over_static_methods;
 import 'prefer_contains_test.dart' as prefer_contains;
+import 'prefer_double_quotes_test.dart' as prefer_double_quotes;
 import 'prefer_expression_function_bodies_test.dart'
     as prefer_expression_function_bodies;
 import 'prefer_final_fields_test.dart' as prefer_final_fields;
@@ -252,6 +253,7 @@ void main() {
   prefer_const_literals_to_create_immutables.main();
   prefer_constructors_over_static_methods.main();
   prefer_contains.main();
+  prefer_double_quotes.main();
   prefer_expression_function_bodies.main();
   prefer_final_fields.main();
   prefer_final_in_for_each.main();

test/rules/prefer_double_quotes_test.dart

@@ -0,0 +1,116 @@
+// Copyright (c) 2023, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../rule_test_support.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(PreferDoubleQuotesTest);
+  });
+}
+
+@reflectiveTest
+class PreferDoubleQuotesTest extends LintRuleTest {
+  @override
+  String get lintRule => 'prefer_double_quotes';
+
+  test_doubleQuotes() async {
+    await assertNoDiagnostics(r'''
+var s = "uses double";
+''');
+  }
+
+  test_doubleQuotes_raw() async {
+    await assertNoDiagnostics(r'''
+var s = r"uses double";
+''');
+  }
+
+  test_doubleQuotes_triple_raw() async {
+    await assertNoDiagnostics(r'''
+var s = r"""uses double""";
+''');
+  }
+
+  test_doubleQuotes_withInterpolation() async {
+    await assertNoDiagnostics(r'''
+var x = "x";
+var s = "uses double $x";
+''');
+  }
+
+  test_doubleQuotes_withInterpolationWithSingleQuote() async {
+    await assertNoDiagnostics(r'''
+var x = "x";
+var s = "foo ${x == 'x'} bar";
+''');
+  }
+
+  test_singleQuote() async {
+    await assertDiagnostics(r'''
+var s = 'no quote';
+''', [
+      lint(8, 10),
+    ]);
+  }
+
+  test_singleQuote_hasDoubleQuote_withInterpolation() async {
+    await assertNoDiagnostics(r'''
+var x = "x";
+var s = 'has double quote " $x';
+''');
+  }
+
+  test_singleQuote_hasDoubleQuotes() async {
+    await assertNoDiagnostics(r'''
+var s = 'has double quote "';
+''');
+  }
+
+  test_singleQuote_raw() async {
+    await assertDiagnostics(r'''
+var s = r'no double quote';
+''', [
+      lint(8, 18),
+    ]);
+  }
+
+  test_singleQuote_raw_hasDoubleQuotes() async {
+    await assertNoDiagnostics(r'''
+var s = r'has double quote "';
+''');
+  }
+
+  test_singleQuote_triple_raw() async {
+    await assertDiagnostics(r"""
+var s = r'''no double quote''';
+""", [
+      lint(8, 22),
+    ]);
+  }
+
+  test_singleQuote_triple_raw_hasDouble() async {
+    await assertNoDiagnostics(r"""
+var s = r'''has double quote "''';
+""");
+  }
+
+  test_singleQuote_withInterpolation() async {
+    await assertDiagnostics(r'''
+var x = "x";
+var s = 'no double quote $x';
+''', [
+      lint(21, 20),
+    ]);
+  }
+
+  test_singleQuote_withInterpolationWithDoubleQuotes() async {
+    await assertNoDiagnostics(r'''
+var x = "x";
+var s = 'foo ${x == "x"} bar';
+''');
+  }
+}