test/result/result_test.dart

// Copyright (c) 2013, 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:async";
import "dart:collection";

import "package:async/async.dart";
import "package:stack_trace/stack_trace.dart";
import "package:test/test.dart";

void main() {
  var stack = Trace.current();

  test("create result value", () {
    Result<int> result = Result<int>.value(42);
    expect(result.isValue, isTrue);
    expect(result.isError, isFalse);
    ValueResult value = result.asValue;
    expect(value.value, equals(42));
  });

  test("create result value 2", () {
    Result<int> result = ValueResult<int>(42);
    expect(result.isValue, isTrue);
    expect(result.isError, isFalse);
    ValueResult<int> value = result.asValue;
    expect(value.value, equals(42));
  });

  test("create result error", () {
    Result<bool> result = Result<bool>.error("BAD", stack);
    expect(result.isValue, isFalse);
    expect(result.isError, isTrue);
    ErrorResult error = result.asError;
    expect(error.error, equals("BAD"));
    expect(error.stackTrace, same(stack));
  });

  test("create result error 2", () {
    Result<bool> result = ErrorResult("BAD", stack);
    expect(result.isValue, isFalse);
    expect(result.isError, isTrue);
    ErrorResult error = result.asError;
    expect(error.error, equals("BAD"));
    expect(error.stackTrace, same(stack));
  });

  test("create result error no stack", () {
    Result<bool> result = Result<bool>.error("BAD");
    expect(result.isValue, isFalse);
    expect(result.isError, isTrue);
    ErrorResult error = result.asError;
    expect(error.error, equals("BAD"));
    expect(error.stackTrace, isNull);
  });

  test("complete with value", () {
    Result<int> result = ValueResult<int>(42);
    var c = Completer<int>();
    c.future.then(expectAsync1((int v) {
      expect(v, equals(42));
    }), onError: (e, s) {
      fail("Unexpected error");
    });
    result.complete(c);
  });

  test("complete with error", () {
    Result<bool> result = ErrorResult("BAD", stack);
    var c = Completer<bool>();
    c.future.then((bool v) {
      fail("Unexpected value $v");
    }, onError: expectAsync2((e, s) {
      expect(e, equals("BAD"));
      expect(s, same(stack));
    }));
    result.complete(c);
  });

  test("add sink value", () {
    var result = ValueResult<int>(42);
    EventSink<int> sink = TestSink(onData: expectAsync1((v) {
      expect(v, equals(42));
    }));
    result.addTo(sink);
  });

  test("add sink error", () {
    Result<bool> result = ErrorResult("BAD", stack);
    EventSink<bool> sink = TestSink(onError: expectAsync2((e, s) {
      expect(e, equals("BAD"));
      expect(s, same(stack));
    }));
    result.addTo(sink);
  });

  test("value as future", () {
    Result<int> result = ValueResult<int>(42);
    result.asFuture.then(expectAsync1((int v) {
      expect(v, equals(42));
    }), onError: (e, s) {
      fail("Unexpected error");
    });
  });

  test("error as future", () {
    Result<bool> result = ErrorResult("BAD", stack);
    result.asFuture.then((bool v) {
      fail("Unexpected value $v");
    }, onError: expectAsync2((e, s) {
      expect(e, equals("BAD"));
      expect(s, same(stack));
    }));
  });

  test("capture future value", () {
    Future<int> value = Future<int>.value(42);
    Result.capture(value).then(expectAsync1((Result result) {
      expect(result.isValue, isTrue);
      expect(result.isError, isFalse);
      ValueResult value = result.asValue;
      expect(value.value, equals(42));
    }), onError: (e, s) {
      fail("Unexpected error: $e");
    });
  });

  test("capture future error", () {
    Future<bool> value = Future<bool>.error("BAD", stack);
    Result.capture(value).then(expectAsync1((Result result) {
      expect(result.isValue, isFalse);
      expect(result.isError, isTrue);
      ErrorResult error = result.asError;
      expect(error.error, equals("BAD"));
      expect(error.stackTrace, same(stack));
    }), onError: (e, s) {
      fail("Unexpected error: $e");
    });
  });

  test("release future value", () {
    Future<Result<int>> future =
        Future<Result<int>>.value(Result<int>.value(42));
    Result.release(future).then(expectAsync1((v) {
      expect(v, equals(42));
    }), onError: (e, s) {
      fail("Unexpected error: $e");
    });
  });

  test("release future error", () {
    // An error in the result is unwrapped and reified by release.
    Future<Result<bool>> future =
        Future<Result<bool>>.value(Result<bool>.error("BAD", stack));
    Result.release(future).then((v) {
      fail("Unexpected value: $v");
    }, onError: expectAsync2((e, s) {
      expect(e, equals("BAD"));
      expect(s, same(stack));
    }));
  });

  test("release future real error", () {
    // An error in the error lane is passed through by release.
    Future<Result<bool>> future = Future<Result<bool>>.error("BAD", stack);
    Result.release(future).then((v) {
      fail("Unexpected value: $v");
    }, onError: expectAsync2((e, s) {
      expect(e, equals("BAD"));
      expect(s, same(stack));
    }));
  });

  test("capture stream", () {
    var c = StreamController<int>();
    var stream = Result.captureStream(c.stream);
    var expectedList = Queue.from(
        [Result.value(42), Result.error("BAD", stack), Result.value(37)]);
    void listener(Result actual) {
      expect(expectedList.isEmpty, isFalse);
      expectResult(actual, expectedList.removeFirst());
    }

    stream.listen(expectAsync1(listener, count: 3),
        onDone: expectAsync0(() {}), cancelOnError: true);
    c.add(42);
    c.addError("BAD", stack);
    c.add(37);
    c.close();
  });

  test("release stream", () {
    StreamController<Result<int>> c = StreamController<Result<int>>();
    Stream<int> stream = Result.releaseStream(c.stream);
    var events = [
      Result<int>.value(42),
      Result<int>.error("BAD", stack),
      Result<int>.value(37)
    ];
    // Expect the data events, and an extra error event.
    var expectedList = Queue.from(events)..add(Result.error("BAD2", stack));

    void dataListener(int v) {
      expect(expectedList.isEmpty, isFalse);
      Result expected = expectedList.removeFirst();
      expect(expected.isValue, isTrue);
      expect(v, equals(expected.asValue.value));
    }

    void errorListener(error, StackTrace stackTrace) {
      expect(expectedList.isEmpty, isFalse);
      Result expected = expectedList.removeFirst();
      expect(expected.isError, isTrue);
      expect(error, equals(expected.asError.error));
      expect(stackTrace, same(expected.asError.stackTrace));
    }

    stream.listen(expectAsync1(dataListener, count: 2),
        onError: expectAsync2(errorListener, count: 2),
        onDone: expectAsync0(() {}));
    for (Result<int> result in events) {
      c.add(result); // Result value or error in data line.
    }
    c.addError("BAD2", stack); // Error in error line.
    c.close();
  });

  test("release stream cancel on error", () {
    StreamController<Result<int>> c = StreamController<Result<int>>();
    Stream<int> stream = Result.releaseStream(c.stream);
    stream.listen(expectAsync1((v) {
      expect(v, equals(42));
    }), onError: expectAsync2((e, s) {
      expect(e, equals("BAD"));
      expect(s, same(stack));
    }), onDone: () {
      fail("Unexpected done event");
    }, cancelOnError: true);
    c.add(Result.value(42));
    c.add(Result.error("BAD", stack));
    c.add(Result.value(37));
    c.close();
  });

  test("flatten error 1", () {
    Result<int> error = Result<int>.error("BAD", stack);
    Result<int> flattened =
        Result.flatten(Result<Result<int>>.error("BAD", stack));
    expectResult(flattened, error);
  });

  test("flatten error 2", () {
    Result<int> error = Result<int>.error("BAD", stack);
    Result<Result<int>> result = Result<Result<int>>.value(error);
    Result<int> flattened = Result.flatten(result);
    expectResult(flattened, error);
  });

  test("flatten value", () {
    Result<Result<int>> result =
        Result<Result<int>>.value(Result<int>.value(42));
    expectResult(Result.flatten(result), Result<int>.value(42));
  });

  test("handle unary", () {
    ErrorResult result = Result.error("error", stack);
    bool called = false;
    result.handle((error) {
      called = true;
      expect(error, "error");
    });
    expect(called, isTrue);
  });

  test("handle binary", () {
    ErrorResult result = Result.error("error", stack);
    bool called = false;
    result.handle((error, stackTrace) {
      called = true;
      expect(error, "error");
      expect(stackTrace, same(stack));
    });
    expect(called, isTrue);
  });

  test("handle unary and binary", () {
    ErrorResult result = Result.error("error", stack);
    bool called = false;
    result.handle((error, [stackTrace]) {
      called = true;
      expect(error, "error");
      expect(stackTrace, same(stack));
    });
    expect(called, isTrue);
  });

  test("handle neither unary nor binary", () {
    ErrorResult result = Result.error("error", stack);
    expect(() => result.handle(() => fail("unreachable")), throwsA(anything));
    expect(() => result.handle((a, b, c) => fail("unreachable")),
        throwsA(anything));
    expect(() => result.handle((a, b, {c}) => fail("unreachable")),
        throwsA(anything));
    expect(() => result.handle((a, {b}) => fail("unreachable")),
        throwsA(anything));
    expect(() => result.handle(({a, b}) => fail("unreachable")),
        throwsA(anything));
    expect(
        () => result.handle(({a}) => fail("unreachable")), throwsA(anything));
  });
}

void expectResult(Result actual, Result expected) {
  expect(actual.isValue, equals(expected.isValue));
  expect(actual.isError, equals(expected.isError));
  if (actual.isValue) {
    expect(actual.asValue.value, equals(expected.asValue.value));
  } else {
    expect(actual.asError.error, equals(expected.asError.error));
    expect(actual.asError.stackTrace, same(expected.asError.stackTrace));
  }
}

class TestSink<T> implements EventSink<T> {
  final Function onData;
  final Function onError;
  final Function onDone;

  TestSink(
      {void this.onData(T data) = _nullData,
      void this.onError(e, StackTrace s) = _nullError,
      void this.onDone() = _nullDone});

  void add(T value) {
    onData(value);
  }

  void addError(error, [StackTrace stack]) {
    onError(error, stack);
  }

  void close() {
    onDone();
  }

  static void _nullData(value) {
    fail("Unexpected sink add: $value");
  }

  static void _nullError(e, StackTrace s) {
    fail("Unexpected sink addError: $e");
  }

  static void _nullDone() {
    fail("Unepxected sink close");
  }
}