Merge pull request #151 from byshy/prefer_single_quotes

Add prefer single quotes rule

example/analysis_options.yaml

@@ -56,6 +56,7 @@ dart_code_linter:
     - no-blank-line-before-single-return
     - no-boolean-literal-compare
     - no-empty-block
+    - prefer-single-quotes
     - no-equal-then-else
     - prefer-async-await
     - prefer-correct-type-name:

lib/src/analyzers/lint_analyzer/rules/rules_factory.dart

@@ -71,6 +71,7 @@ import 'rules_list/prefer_last/prefer_last_rule.dart';
 import 'rules_list/prefer_match_file_name/prefer_match_file_name_rule.dart';
 import 'rules_list/prefer_moving_to_variable/prefer_moving_to_variable_rule.dart';
 import 'rules_list/prefer_provide_intl_description/prefer_provide_intl_description_rule.dart';
+import 'rules_list/prefer_single_quotes/prefer_single_qoutes.dart';
 import 'rules_list/prefer_single_widget_per_file/prefer_single_widget_per_file_rule.dart';
 import 'rules_list/prefer_static_class/prefer_static_class_rule.dart';
 import 'rules_list/prefer_trailing_comma/prefer_trailing_comma_rule.dart';
@@ -134,6 +135,7 @@ final _implementedRules = <String, Rule Function(Map<String, Object>)>{
   NewlineBeforeReturnRule.ruleId: NewlineBeforeReturnRule.new,
   NoBlankLineBeforeSingleReturnRule.ruleId: NoBlankLineBeforeSingleReturnRule.new,
   PreferFirstOrNullRule.ruleId: PreferFirstOrNullRule.new,
+  PreferSingleQuotesRule.ruleId: PreferSingleQuotesRule.new,
   NoBooleanLiteralCompareRule.ruleId: NoBooleanLiteralCompareRule.new,
   NoEmptyBlockRule.ruleId: NoEmptyBlockRule.new,
   NoEqualArgumentsRule.ruleId: NoEqualArgumentsRule.new,

lib/src/analyzers/lint_analyzer/rules/rules_list/prefer_single_quotes/prefer_single_qoutes.dart

@@ -0,0 +1,61 @@
+// ignore_for_file: public_member_api_docs
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+
+import '../../../../../utils/node_utils.dart';
+import '../../../lint_utils.dart';
+import '../../../models/internal_resolved_unit_result.dart';
+import '../../../models/issue.dart';
+import '../../../models/replacement.dart';
+import '../../../models/severity.dart';
+import '../../models/dart_rule.dart';
+import '../../rule_utils.dart';
+
+part 'visitor.dart';
+
+class PreferSingleQuotesRule extends DartRule {
+  static const ruleId = 'prefer-single-quotes';
+  static const _warningMessage = 'Use single quotation marks instead of double quotations.';
+  static const _replaceComment = "Replace with ''.";
+
+  PreferSingleQuotesRule([Map<String, Object> config = const {}])
+      : super(
+          id: ruleId,
+          severity: readSeverity(config, Severity.style),
+          excludes: readExcludes(config),
+          includes: readIncludes(config),
+        );
+
+  @override
+  Iterable<Issue> check(InternalResolvedUnitResult source) {
+    final visitor = _Visitor();
+    source.unit.visitChildren(visitor);
+
+    return visitor.expressions
+        .map((expression) => createIssue(
+              rule: this,
+              location: nodeLocation(node: expression, source: source),
+              message: _warningMessage,
+              replacement: _createReplacement(expression),
+            ))
+        .toList(growable: false);
+  }
+
+  Replacement _createReplacement(Expression expression) {
+    if (expression is StringLiteral) {
+      final originalString = expression.stringValue ?? '';
+      final singleQuotedString = "'$originalString'";
+
+      return Replacement(
+        comment: _replaceComment,
+        replacement: singleQuotedString,
+      );
+    }
+
+    return Replacement(
+      comment: _replaceComment,
+      replacement: expression.toSource(),
+    );
+  }
+}

lib/src/analyzers/lint_analyzer/rules/rules_list/prefer_single_quotes/visitor.dart

@@ -0,0 +1,18 @@
+part of 'prefer_single_qoutes.dart';
+
+class _Visitor extends RecursiveAstVisitor<void> {
+  final _expressions = <Expression>[];
+
+  Iterable<Expression> get expressions => _expressions;
+
+  @override
+  void visitSimpleStringLiteral(SimpleStringLiteral node) {
+    super.visitSimpleStringLiteral(node);
+
+    if (node.isSingleQuoted) {
+      return; // Already using single quotes
+    }
+
+    _expressions.add(node);
+  }
+}

test/src/analyzers/lint_analyzer/rules/rules_list/prefer_single_quotes/examples/example.dart

@@ -0,0 +1,18 @@
+// ignore_for_file: unnecessary_cast, unused_local_variable
+
+import 'dart:collection';
+
+void func() {
+  final String value1 = "some value"; // Lint
+  final String value2 = 'some value';
+
+  final String value3 = "some value \"another text\""; // Lint
+  final String value4 = 'some value \"another text\"';
+
+  final String value5 = """
+  multi line text
+  """;
+  final String value6 = '''
+  multi line text
+  ''';
+}

test/src/analyzers/lint_analyzer/rules/rules_list/prefer_single_quotes/prefer_single_quotes_rule_test.dart

@@ -0,0 +1,67 @@
+import 'package:dart_code_linter/src/analyzers/lint_analyzer/models/severity.dart';
+import 'package:dart_code_linter/src/analyzers/lint_analyzer/rules/rules_list/prefer_single_quotes/prefer_single_qoutes.dart';
+import 'package:test/test.dart';
+
+import '../../../../../helpers/rule_test_helper.dart';
+
+const _examplePath = 'prefer_single_quotes/examples/example.dart';
+
+void main() {
+  group(
+    'PreferSingleQuotesRule',
+    () {
+      test('initialization', () async {
+        final unit = await RuleTestHelper.resolveFromFile(_examplePath);
+        final issues = PreferSingleQuotesRule().check(unit);
+
+        RuleTestHelper.verifyInitialization(
+          issues: issues,
+          ruleId: PreferSingleQuotesRule.ruleId,
+          severity: Severity.style,
+        );
+      });
+
+      test('reports about found issues', () async {
+        final unit = await RuleTestHelper.resolveFromFile(_examplePath);
+        final issues = PreferSingleQuotesRule().check(unit);
+
+        RuleTestHelper.verifyIssues(
+          issues: issues,
+          startLines: [
+            6,
+            9,
+            12,
+          ],
+          startColumns: [
+            25,
+            25,
+            25,
+          ],
+          messages: [
+            'Use single quotation marks instead of double quotations.',
+            'Use single quotation marks instead of double quotations.',
+            'Use single quotation marks instead of double quotations.',
+          ],
+          replacementComments: [
+            "Replace with ''.",
+            "Replace with ''.",
+            "Replace with ''.",
+          ],
+          replacements: [
+            "'some value'",
+            '\'some value "another text"\'',
+            "'  multi line text\n"
+                "  '",
+          ],
+          locationTexts: [
+            '"some value"',
+            r'"some value \"another text\""',
+            '"""\n'
+                '  multi line text\n'
+                '  """',
+          ],
+        );
+      });
+    },
+  );
+}