feat: add prefer_mirror_test_structure rule (#379)

Co-authored-by: Illia Aihistov <illia.aihistov-us@solid.software>

Author: solid-illiaaihistov

lib/analysis_options.yaml

@@ -110,6 +110,7 @@ solid_lints:
     prefer_first: true
     prefer_last: true
     prefer_match_file_name: true
+    prefer_mirror_test_structure: true
     proper_super_calls: true
     # Disabled for now due to conflict with
     # `always_put_required_named_parameters_first`.

lib/main.dart

@@ -33,6 +33,7 @@ import 'package:solid_lints/src/lints/prefer_early_return/prefer_early_return_ru
 import 'package:solid_lints/src/lints/prefer_first/prefer_first_rule.dart';
 import 'package:solid_lints/src/lints/prefer_last/prefer_last_rule.dart';
 import 'package:solid_lints/src/lints/prefer_match_file_name/prefer_match_file_name_rule.dart';
+import 'package:solid_lints/src/lints/prefer_mirror_test_structure/prefer_mirror_test_structure_rule.dart';
 import 'package:solid_lints/src/lints/proper_super_calls/proper_super_calls_rule.dart';
 import 'package:solid_lints/src/lints/use_descriptive_names_for_type_parameters/use_descriptive_names_for_type_parameters_rule.dart';
 import 'package:solid_lints/src/lints/use_nearest_context/use_nearest_context_rule.dart';
@@ -89,6 +90,7 @@ class SolidLintsPlugin extends Plugin {
       PreferFirstRule(),
       PreferLastRule(),
       PreferMatchFileNameRule(analysisOptionsLoader: analysisLoader),
+      PreferMirrorTestStructureRule(),
       ProperSuperCallsRule(),
       UseDescriptiveNamesForTypeParametersRule(
         analysisOptionsLoader: analysisLoader,

lib/src/lints/prefer_mirror_test_structure/prefer_mirror_test_structure_rule.dart

@@ -0,0 +1,73 @@
+import 'package:analyzer/analysis_rule/rule_context.dart';
+import 'package:analyzer/analysis_rule/rule_visitor_registry.dart';
+import 'package:analyzer/error/error.dart';
+import 'package:solid_lints/src/lints/prefer_mirror_test_structure/visitors/prefer_mirror_test_structure_visitor.dart';
+import 'package:solid_lints/src/models/solid_lint_rule.dart';
+
+/// Warns when the test file folder structure does not mirror the 'lib/' folder
+/// structure of the imported implementation file.
+///
+/// Keeping the same folder structure for your tests makes it easier to locate
+/// test files and allows using IDE commands such as 'Go to Test/Implementation
+/// File'.
+///
+/// This rule highlights test files that import implementation files with the
+/// same name (without the `_test` suffix) when their relative directory path in
+/// `test/` does not match the relative directory path in `lib/`.
+///
+/// ### Example
+///
+/// #### BAD:
+///
+/// File: `test/auth_service_test.dart`
+///
+/// ```dart
+/// import 'package:my_app/src/services/auth_service.dart'; // LINT
+/// ```
+///
+/// #### GOOD:
+///
+/// File: `test/src/services/auth_service_test.dart`
+///
+/// ```dart
+/// import 'package:my_app/src/services/auth_service.dart'; // OK
+/// ```
+///
+class PreferMirrorTestStructureRule extends SolidLintRule<void> {
+  /// Name of the lint.
+  static const lintName = 'prefer_mirror_test_structure';
+
+  static const _code = LintCode(
+    lintName,
+    "The test file folder structure does not mirror the 'lib/' folder "
+    'structure.',
+    correctionMessage: "Move the test file to '{0}'.",
+  );
+
+  /// Creates an instance of [PreferMirrorTestStructureRule].
+  PreferMirrorTestStructureRule()
+    : super(
+        name: lintName,
+        description:
+            'Warns when the test file folder structure does not mirror the '
+            "'lib/' folder structure.",
+      );
+
+  @override
+  DiagnosticCode get diagnosticCode => _code;
+
+  @override
+  void registerNodeProcessors(
+    RuleVisitorRegistry registry,
+    RuleContext context,
+  ) {
+    super.registerNodeProcessors(registry, context);
+
+    final visitor = PreferMirrorTestStructureVisitor(
+      rule: this,
+      context: context,
+    );
+
+    registry.addCompilationUnit(this, visitor);
+  }
+}

lib/src/lints/prefer_mirror_test_structure/visitors/prefer_mirror_test_structure_visitor.dart

@@ -0,0 +1,80 @@
+import 'package:analyzer/analysis_rule/rule_context.dart';
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:path/path.dart' as p;
+import 'package:solid_lints/src/lints/prefer_mirror_test_structure/prefer_mirror_test_structure_rule.dart';
+
+/// The AST visitor that checks if test files mirror the folder structure of
+/// their corresponding implementation files.
+class PreferMirrorTestStructureVisitor extends SimpleAstVisitor<void> {
+  static const _testSuffix = '_test.dart';
+  static const _dartSuffix = '.dart';
+  static const _testDirName = 'test';
+  static const _libDirName = 'lib';
+
+  /// The rule that instantiated this visitor.
+  final PreferMirrorTestStructureRule rule;
+
+  /// The context of the current analysis rule.
+  final RuleContext context;
+
+  /// Creates a new instance of [PreferMirrorTestStructureVisitor].
+  PreferMirrorTestStructureVisitor({
+    required this.rule,
+    required this.context,
+  });
+
+  @override
+  void visitCompilationUnit(CompilationUnit node) {
+    final currentUnit = context.currentUnit;
+    final packageRoot = context.package?.root.path;
+    if (currentUnit == null ||
+        packageRoot == null ||
+        !context.isInTestDirectory) {
+      return;
+    }
+
+    final file = currentUnit.file;
+    final fileName = file.shortName;
+    if (!fileName.endsWith(_testSuffix)) return;
+
+    final pathContext = file.provider.pathContext;
+    final testDir = pathContext.relative(
+      file.parent.path,
+      from: pathContext.join(packageRoot, _testDirName),
+    );
+
+    final libRoot = pathContext.join(packageRoot, _libDirName);
+    final targetFileName = fileName.replaceFirst(_testSuffix, _dartSuffix);
+
+    for (final directive in node.directives.whereType<ImportDirective>()) {
+      if (directive.libraryImport?.uri case DirectiveUriWithSource(
+        :final source,
+      )) {
+        final importedPath = source.fullName;
+        if (pathContext.basename(importedPath) != targetFileName ||
+            !pathContext.isWithin(libRoot, importedPath)) {
+          continue;
+        }
+
+        final libDir = pathContext.relative(
+          pathContext.dirname(importedPath),
+          from: libRoot,
+        );
+        if (libDir == testDir) return;
+
+        final nativePath = pathContext.normalize(
+          pathContext.join(_testDirName, libDir, fileName),
+        );
+        currentUnit.diagnosticReporter.atNode(
+          directive.uri,
+          rule.diagnosticCode,
+          arguments: [p.posix.joinAll(pathContext.split(nativePath))],
+        );
+
+        return;
+      }
+    }
+  }
+}