pkg/analyzer/test/id_tests/nullability_test.dart

// Copyright (c) 2019, 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 'dart:io';

import 'package:_fe_analyzer_shared/src/testing/id.dart' show ActualData, Id;
import 'package:_fe_analyzer_shared/src/testing/id_testing.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/dart/element/type.dart';
import 'package:analyzer/dart/element/type_system.dart';
import 'package:analyzer/src/dart/analysis/testing_data.dart';
import 'package:analyzer/src/dart/ast/extensions.dart';
import 'package:analyzer/src/util/ast_data_extractor.dart';

import '../util/id_testing_helper.dart';

main(List<String> args) {
  Directory dataDir = Directory.fromUri(
    Platform.script.resolve(
      '../../../_fe_analyzer_shared/test/flow_analysis/nullability/data',
    ),
  );
  return runTests<String>(
    dataDir,
    args: args,
    createUriForFileName: createUriForFileName,
    onFailure: onFailure,
    runTest: runTestFor(const _NullabilityDataComputer(), [
      analyzerDefaultConfig,
    ]),
  );
}

class _NullabilityDataComputer extends DataComputer<String> {
  const _NullabilityDataComputer();

  @override
  DataInterpreter<String> get dataValidator =>
      const _NullabilityDataInterpreter();

  @override
  void computeUnitData(
    TestingData testingData,
    CompilationUnit unit,
    Map<Id, ActualData<String>> actualMap,
  ) {
    var unitElement = unit.declaredFragment!;
    _NullabilityDataExtractor(
      unitElement.source.uri,
      actualMap,
      unitElement.element.typeSystem,
    ).run(unit);
  }
}

class _NullabilityDataExtractor extends AstDataExtractor<String> {
  final TypeSystem _typeSystem;

  _NullabilityDataExtractor(super.uri, super.actualMap, this._typeSystem);

  @override
  String? computeNodeValue(Id id, AstNode node) {
    if (node is SimpleIdentifier &&
        node.inGetterContext() &&
        !node.inDeclarationContext()) {
      var element = node.element;
      if (element is LocalVariableElement2 ||
          element is FormalParameterElement) {
        var promotedType = _readType(node);
        var declaredType = (element as VariableElement2).type;
        var isPromoted = promotedType != declaredType;
        if (isPromoted &&
            _typeSystem.isPotentiallyNullable(declaredType) &&
            !_typeSystem.isPotentiallyNullable(promotedType)) {
          return 'nonNullable';
        }
      }
    }
    return null;
  }

  static DartType _readType(SimpleIdentifier node) {
    var parent = node.parent;
    if (parent is AssignmentExpression && parent.leftHandSide == node) {
      return parent.readType!;
    } else if (parent is PostfixExpression) {
      return parent.readType ?? node.typeOrThrow;
    } else if (parent is PrefixExpression) {
      return parent.readType ?? node.typeOrThrow;
    } else {
      return node.typeOrThrow;
    }
  }
}

class _NullabilityDataInterpreter implements DataInterpreter<String> {
  const _NullabilityDataInterpreter();

  @override
  String getText(String actualData, [String? indentation]) => actualData;

  @override
  String? isAsExpected(String actualData, String? expectedData) {
    if (actualData == expectedData) {
      return null;
    } else {
      return 'Expected $expectedData, got $actualData';
    }
  }

  @override
  bool isEmpty(String actualData) => actualData.isEmpty;
}