pkg/front_end/test/fasta/type_inference/type_schema_elimination_nnbd_test.dart

// Copyright (c) 2020, 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:front_end/src/fasta/type_inference/type_schema.dart';
import 'package:front_end/src/fasta/type_inference/type_schema_elimination.dart'
    as typeSchemaElimination;
import 'package:kernel/ast.dart';
import 'package:kernel/testing/type_parser_environment.dart';
import 'package:test/test.dart';
import 'package:test_reflective_loader/test_reflective_loader.dart';

main() {
  defineReflectiveSuite(() {
    defineReflectiveTests(TypeSchemaEliminationTest);
  });
}

@reflectiveTest
class TypeSchemaEliminationTest {
  final Env env = new Env("", isNonNullableByDefault: true);
  final Map<String, DartType Function()> additionalTypes = {
    "UNKNOWN": () => new UnknownType()
  };

  DartType greatestClosure(DartType schema) {
    return typeSchemaElimination.greatestClosure(
        schema, const DynamicType(), const NeverType(Nullability.nonNullable));
  }

  DartType leastClosure(DartType schema) {
    return typeSchemaElimination.leastClosure(
        schema, const DynamicType(), const NeverType(Nullability.nonNullable));
  }

  void testGreatest(String type, String expectedClosure) {
    expect(
        greatestClosure(env.parseType(type, additionalTypes: additionalTypes)),
        env.parseType(expectedClosure, additionalTypes: additionalTypes));
  }

  void testLeast(String type, String expectedClosure) {
    expect(leastClosure(env.parseType(type, additionalTypes: additionalTypes)),
        env.parseType(expectedClosure, additionalTypes: additionalTypes));
  }

  void test_greatestClosure_contravariant() {
    testGreatest("(UNKNOWN) ->* dynamic", "(Never) ->* dynamic");
    testGreatest("({UNKNOWN foo}) ->* dynamic", "({Never foo}) ->* dynamic");
  }

  void test_greatestClosure_contravariant_contravariant() {
    testGreatest("((UNKNOWN) ->* dynamic) ->* dynamic",
        "((dynamic) ->* dynamic) ->* dynamic");
  }

  void test_greatestClosure_covariant() {
    testGreatest("() ->* UNKNOWN", "() ->* dynamic");
    testGreatest("List<UNKNOWN>*", "List<dynamic>*");
  }

  void test_greatestClosure_function_multipleUnknown() {
    testGreatest("(UNKNOWN, UNKNOWN, {UNKNOWN a, UNKNOWN b}) ->* UNKNOWN",
        "(Never, Never, {Never a, Never b}) ->* dynamic");
  }

  void test_greatestClosure_simple() {
    testGreatest("UNKNOWN", "dynamic");
  }

  void test_leastClosure_contravariant() {
    testLeast("(UNKNOWN) ->* dynamic", "(dynamic) ->* dynamic");
    testLeast("({UNKNOWN foo}) ->* dynamic", "({dynamic foo}) ->* dynamic");
  }

  void test_leastClosure_contravariant_contravariant() {
    testLeast("((UNKNOWN) ->* dynamic) ->* dynamic",
        "((Never) ->* dynamic) ->* dynamic");
  }

  void test_leastClosure_covariant() {
    testLeast("() ->* UNKNOWN", "() ->* Never");
    testLeast("List<UNKNOWN>*", "List<Never>*");
  }

  void test_leastClosure_function_multipleUnknown() {
    testLeast("(UNKNOWN, UNKNOWN, {UNKNOWN a, UNKNOWN b}) ->* UNKNOWN",
        "(dynamic, dynamic, {dynamic a, dynamic b}) ->* Never");
  }

  void test_leastClosure_simple() {
    testLeast("UNKNOWN", "Never");
  }
}