@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class CollectionIsEmptyTester<E> extends AbstractCollectionTester<E> {
  @CollectionSize.Require(ZERO)
  public void testIsEmpty_yes() {
    assertTrue("isEmpty() should return true", collection.isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  public void testIsEmpty_no() {
    assertFalse("isEmpty() should return false", collection.isEmpty());
  }

  }

  @MapFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nonNullWhenNullContained() {
    initMapWithNullValue();
    assertFalse("containsValue(notPresent) should return false", getMap().containsValue(v3()));
  }

  @MapFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nullContained() {
    initMapWithNullValue();

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nonNullWhenNullContained() {
    initCollectionWithNullElement();
    assertFalse("contains(notPresent) should return false", collection.contains(e3()));
  }

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nullContained() {
    initCollectionWithNullElement();

   *
   * <p>Zero is treated as having log2 == 0.
   */
  static double randomDouble(int maxExponent) {
    double result = RANDOM_SOURCE.nextDouble();
    result = Math.scalb(result, RANDOM_SOURCE.nextInt(maxExponent + 1));
    return RANDOM_SOURCE.nextBoolean() ? result : -result;
  }

  /** Returns a random integer between zero and {@code MAX_EXPONENT}. */
  static int randomExponent() {

  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutAll_supportedSomePresent() {
    putAll(MinimalCollection.of(e3(), e0()));
    expectAdded(e3());
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_PUT})
  @CollectionSize.Require(absent = ZERO)
  public void testPutAllSomePresentConcurrentWithEntrySetIteration() {
    assertThrows(

```Python
if not (credentials.username == "stanleyjobson") or not (credentials.password == "swordfish"):
    # Devuelve algún error
    ...
```

Pero al usar `secrets.compare_digest()` será seguro contra un tipo de ataques llamados "timing attacks".

### Timing attacks { #timing-attacks }

¿Pero qué es un "timing attack"?

Imaginemos que algunos atacantes están tratando de adivinar el nombre de usuario y la contraseña.

  @CollectionSize.Require(absent = ZERO)
  public void testContainsValueYes() {
    assertTrue(multimap().containsValue(v0()));
  }

  public void testContainsValueNo() {
    assertFalse(multimap().containsValue(v3()));
  }

  @MapFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContainsNullValueYes() {
    initMultimapWithNullValue();

 * the License.
 */

package com.google.common.collect.testing.google;

import static com.google.common.collect.testing.Helpers.mapEntry;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEYS;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;

import com.google.common.annotations.GwtCompatible;

    assertEmpty(multimap().removeAll(k3()));
    expectUnchanged();
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testRemoveAllPresentKey() {
    assertContentsAnyOrder(multimap().removeAll(k0()), v0());
    expectMissing(e0());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testRemoveAllPropagatesToGet() {

  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(absent = NON_STANDARD_TOSTRING)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testToStringWithNullKey() {
    initMapWithNullKey();
    testToString_formatting();
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(absent = NON_STANDARD_TOSTRING)