FessCrawlerThread crawlerThread = new FessCrawlerThread();
        assertNotNull(crawlerThread, "FessCrawlerThread should be instantiable");
    }

    /**
     * Test URL deduplication in getAnchorSet
     */
    @Test
    public void test_getAnchorSet_deduplication() {
        FessCrawlerThread crawlerThread = new FessCrawlerThread();

        List<String> urls = new ArrayList<>();

///

## Réduire la duplication { #reduce-duplication }

Réduire la duplication de code est l'une des idées centrales de **FastAPI**.

La duplication de code augmente les risques de bogues, de problèmes de sécurité, de désynchronisation du code (lorsque vous mettez à jour un endroit mais pas les autres), etc.

///

## Reduce duplication { #reduce-duplication }

Reducing code duplication is one of the core ideas in **FastAPI**.

As code duplication increments the chances of bugs, security issues, code desynchronization issues (when you update in one place but not in the others), etc.

    }

    @CanIgnoreReturnValue // Sure, why not?
    @Override
    public T apply(T key) {
      awaitUninterruptibly(delayLatch);
      return key;
    }
  }

  /*
   * TODO(cpovirk): eliminate duplication between these tests and those in LegacyMapMakerTests and
   * anywhere else
   */

  public void testInitialCapacity_negative() {
    MapMaker maker = new MapMaker();

    }

    @CanIgnoreReturnValue // Sure, why not?
    @Override
    public T apply(T key) {
      awaitUninterruptibly(delayLatch);
      return key;
    }
  }

  /*
   * TODO(cpovirk): eliminate duplication between these tests and those in LegacyMapMakerTests and
   * anywhere else
   */

  public void testInitialCapacity_negative() {
    MapMaker maker = new MapMaker();

<img src="/img/tutorial/dependencies/image02.png">

## Raccourci { #shortcut }

Mais vous voyez qu'il y a ici de la duplication de code : nous écrivons `CommonQueryParams` deux fois :

//// tab | Python 3.10+

```Python
commons: Annotated[CommonQueryParams, Depends(CommonQueryParams)]
```

////

Додаткові допоміжні функції `fake_password_hasher` і `fake_save_user` лише демонструють можливий потік даних і, звісно, не забезпечують реальної безпеки.

///

## Зменшення дублювання { #reduce-duplication }

Зменшення дублювання коду - одна з ключових ідей у **FastAPI**.

Адже дублювання коду підвищує ймовірність помилок, проблем безпеки, розсинхронізації коду (коли ви оновлюєте в одному місці, але не в інших) тощо.

    inverseFeatures.remove(CollectionFeature.KNOWN_ORDER);
    inverseFeatures.add(MapFeature.REJECTS_DUPLICATES_AT_CREATION);

    return inverseFeatures;
  }

  // TODO(lowasser): can we eliminate the duplication from MapTestSuiteBuilder here?

  private static Set<Feature<?>> computeValuesSetFeatures(Set<Feature<?>> mapFeatures) {
    Set<Feature<?>> valuesCollectionFeatures = computeCommonDerivedCollectionFeatures(mapFeatures);

 *     list of available routes.
 *
 * If the pool gains an eligible connection while DNS, TCP, or TLS work is in flight, this finder
 * will prefer pooled connections. Only pooled HTTP/2 connections are used for such de-duplication.
 *
 * It is possible to cancel the finding process by canceling its call.
 *
 * Implementations of this interface are not thread-safe. Each instance is thread-confined to the
 * thread executing the call.
 */

    inverseFeatures.remove(CollectionFeature.KNOWN_ORDER);
    inverseFeatures.add(MapFeature.REJECTS_DUPLICATES_AT_CREATION);

    return inverseFeatures;
  }

  // TODO(lowasser): can we eliminate the duplication from MapTestSuiteBuilder here?

  private static Set<Feature<?>> computeValuesSetFeatures(Set<Feature<?>> mapFeatures) {
    Set<Feature<?>> valuesCollectionFeatures = computeCommonDerivedCollectionFeatures(mapFeatures);