assertEquals("correct", f.apply(new Object()));
    assertEquals("correct", f.apply(null));

    Function<@Nullable Object, @Nullable String> g = Functions.constant(null);
    assertEquals(null, g.apply(2));
    assertEquals(null, g.apply(null));

    new EqualsTester()
        .addEqualityGroup(f, Functions.constant("correct"))

    assertEquals(1, (int) iter.peek());
    assertEquals(1, (int) iter.next());

    /*
     * We test peek() after various calls to make sure that one bad call doesn't interfere with its
     * ability to throw the correct exception in the future.
     */
    assertThrows(NoSuchElementException.class, iter::peek);
    assertThrows(NoSuchElementException.class, iter::peek);
    assertThrows(NoSuchElementException.class, iter::next);

    @ParameterizedTest
    @ValueSource(strings = { "NONE", "NO_TIMEOUT", "NO_RETRY", "RETAIN_PAYLOAD" })
    @DisplayName("valueOf(name) returns the correct enum and toString matches name")
    void valueOfResolvesNamesAndToString(String name) {
        RequestParam rp = RequestParam.valueOf(name);
        assertNotNull(rp);

    if (dividend >= 0) {
      return dividend / divisor;
    }

    /*
     * Otherwise, approximate the quotient, check, and correct if necessary. Our approximation is
     * guaranteed to be either exact or one less than the correct value. This follows from fact that
     * floor(floor(x)/i) == floor(x/i) for any real x and integer i != 0. The proof is not quite
     * trivial.
     */

        }

        // Verify that the scroll method exists with correct signature
        try {
            SearchEngineUtil.class.getMethod("scroll", String.class, java.util.function.Function.class);
        } catch (NoSuchMethodException e) {
            fail("scroll method should exist with correct signature");
        }
    }

<img src="/img/tutorial/security/image12.png">

## Verifique o usuário

Aqui está um exemplo mais completo.

Utilize uma dependência para verificar se o usuário e a senha estão corretos.

Para isso, utilize o módulo padrão do Python <a href="https://docs.python.org/3/library/secrets.html" class="external-link" target="_blank">`secrets`</a> para verificar o usuário e senha.

        assertNotNull(DialectVersion.SMB300);
        assertNotNull(DialectVersion.SMB302);
        assertNotNull(DialectVersion.SMB311);
    }

    @Test
    @DisplayName("Should have correct version ordering")
    void testVersionOrdering() {
        // SMB versions should be ordered chronologically
        assertTrue(DialectVersion.SMB1.compareTo(DialectVersion.SMB202) < 0);

        // Test with various messages
        String message = "Test error message";
        TransportException exception = new TransportException(message);

        // Verify the exception has the correct message
        assertNotNull(exception);
        assertEquals(message, exception.getMessage());
        assertNull(exception.getCause());

        // Test with empty string

Of course, the attackers would not try all this by hand, they would write a program to do it, possibly with thousands or millions of tests per second. And they would get just one extra correct letter at a time.

But doing that, in some minutes or hours the attackers would have guessed the correct username and password, with the "help" of our application, just using the time taken to answer.

#### Fix it with `secrets.compare_digest()` { #fix-it-with-secrets-compare-digest }

    assertEquals("correct", f.apply(new Object()));
    assertEquals("correct", f.apply(null));

    Function<@Nullable Object, @Nullable String> g = Functions.constant(null);
    assertEquals(null, g.apply(2));
    assertEquals(null, g.apply(null));

    new EqualsTester()
        .addEqualityGroup(f, Functions.constant("correct"))