pkgs/stream_transform/test/debounce_test.dart

// Copyright (c) 2017, 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 'package:test/test.dart';
import 'package:stream_transform/stream_transform.dart';

import 'utils.dart';

void main() {
  for (var streamType in streamTypes) {
    group('Stream type [$streamType]', () {
      group('debounce - trailing', () {
        late StreamController<int> values;
        late List<int> emittedValues;
        late bool valuesCanceled;
        late bool isDone;
        late List<String> errors;
        late StreamSubscription<int> subscription;
        late Stream<int> transformed;

        setUp(() async {
          valuesCanceled = false;
          values = createController(streamType)
            ..onCancel = () {
              valuesCanceled = true;
            };
          emittedValues = [];
          errors = [];
          isDone = false;
          transformed = values.stream.debounce(const Duration(milliseconds: 5));
          subscription = transformed
              .listen(emittedValues.add, onError: errors.add, onDone: () {
            isDone = true;
          });
        });

        test('cancels values', () async {
          await subscription.cancel();
          expect(valuesCanceled, true);
        });

        test('swallows values that come faster than duration', () async {
          values..add(1)..add(2);
          await values.close();
          await waitForTimer(5);
          expect(emittedValues, [2]);
        });

        test('outputs multiple values spaced further than duration', () async {
          values.add(1);
          await waitForTimer(5);
          values.add(2);
          await waitForTimer(5);
          expect(emittedValues, [1, 2]);
        });

        test('waits for pending value to close', () async {
          values.add(1);
          await waitForTimer(5);
          await values.close();
          await Future(() {});
          expect(isDone, true);
        });

        test('closes output if there are no pending values', () async {
          values.add(1);
          await waitForTimer(5);
          values.add(2);
          await Future(() {});
          await values.close();
          expect(isDone, false);
          await waitForTimer(5);
          expect(isDone, true);
        });

        if (streamType == 'broadcast') {
          test('multiple listeners all get values', () async {
            var otherValues = [];
            transformed.listen(otherValues.add);
            values..add(1)..add(2);
            await waitForTimer(5);
            expect(emittedValues, [2]);
            expect(otherValues, [2]);
          });
        }
      });

      group('debounce - leading', () {
        late StreamController<int> values;
        late List<int> emittedValues;
        late Stream<int> transformed;
        late bool isDone;

        setUp(() async {
          values = createController(streamType);
          emittedValues = [];
          isDone = false;
          transformed = values.stream.debounce(const Duration(milliseconds: 5),
              leading: true, trailing: false)
            ..listen(emittedValues.add, onDone: () {
              isDone = true;
            });
        });

        test('swallows values that come faster than duration', () async {
          values..add(1)..add(2);
          await values.close();
          expect(emittedValues, [1]);
        });

        test('outputs multiple values spaced further than duration', () async {
          values.add(1);
          await waitForTimer(5);
          values.add(2);
          await waitForTimer(5);
          expect(emittedValues, [1, 2]);
        });

        if (streamType == 'broadcast') {
          test('multiple listeners all get values', () async {
            var otherValues = [];
            transformed.listen(otherValues.add);
            values..add(1)..add(2);
            await waitForTimer(5);
            expect(emittedValues, [1]);
            expect(otherValues, [1]);
          });
        }

        test('closes output immediately if not waiting for trailing value',
            () async {
          values.add(1);
          await values.close();
          expect(isDone, true);
        });
      });

      group('debounce - leading and trailing', () {
        late StreamController<int> values;
        late List<int> emittedValues;
        late Stream<int> transformed;

        setUp(() async {
          values = createController(streamType);
          emittedValues = [];
          transformed = values.stream.debounce(const Duration(milliseconds: 5),
              leading: true, trailing: true)
            ..listen(emittedValues.add);
        });

        test('swallows values that come faster than duration', () async {
          values..add(1)..add(2)..add(3);
          await values.close();
          await waitForTimer(5);
          expect(emittedValues, [1, 3]);
        });

        test('outputs multiple values spaced further than duration', () async {
          values.add(1);
          await waitForTimer(5);
          values.add(2);
          await waitForTimer(5);
          expect(emittedValues, [1, 2]);
        });

        if (streamType == 'broadcast') {
          test('multiple listeners all get values', () async {
            var otherValues = [];
            transformed.listen(otherValues.add);
            values..add(1)..add(2);
            await waitForTimer(5);
            expect(emittedValues, [1, 2]);
            expect(otherValues, [1, 2]);
          });
        }
      });

      group('debounceBuffer', () {
        late StreamController<int> values;
        late List<List<int>> emittedValues;
        late List<String> errors;
        late Stream<List<int>> transformed;

        setUp(() async {
          values = createController(streamType);
          emittedValues = [];
          errors = [];
          transformed = values.stream
              .debounceBuffer(const Duration(milliseconds: 5))
                ..listen(emittedValues.add, onError: errors.add);
        });

        test('Emits all values as a list', () async {
          values..add(1)..add(2);
          await values.close();
          await waitForTimer(5);
          expect(emittedValues, [
            [1, 2]
          ]);
        });

        test('separate lists for multiple values spaced further than duration',
            () async {
          values.add(1);
          await waitForTimer(5);
          values.add(2);
          await waitForTimer(5);
          expect(emittedValues, [
            [1],
            [2]
          ]);
        });

        if (streamType == 'broadcast') {
          test('multiple listeners all get values', () async {
            var otherValues = [];
            transformed.listen(otherValues.add);
            values..add(1)..add(2);
            await waitForTimer(5);
            expect(emittedValues, [
              [1, 2]
            ]);
            expect(otherValues, [
              [1, 2]
            ]);
          });
        }
      });
    });
  }
  test('allows nulls', () async {
    final values = Stream<int?>.fromIterable([null]);
    final transformed = values.debounce(const Duration(milliseconds: 1));
    expect(await transformed.toList(), [null]);
  });
}