### Use cases: external service { #use-cases-external-service }

An example could be that you have an external authentication provider that you need to call.

You send it a token and it returns an authenticated user.

This provider might be charging you per request, and calling it might take some extra time than if you had a fixed mock user for tests.

And Pydantic's `Field` returns an instance of `FieldInfo` as well.

`Body` also returns objects of a subclass of `FieldInfo` directly. And there are others you will see later that are subclasses of the `Body` class.

Remember that when you import `Query`, `Path`, and others from `fastapi`, those are actually functions that return special classes.

///

/// tip

        this.fieldName = fieldName;
    }

    /**
     * Returns the target class.
     *
     * @return Target class
     */
    public Class<?> getTargetClass() {
        return targetClass;
    }

    /**
     * Returns the field name.
     *
     * @return Field name
     */
    public String getFieldName() {
        return fieldName;
    }

 * <i>return</i> iterables should make every attempt to return ones of the robust variety.
 *
 * <p>This testing utility is not thread-safe.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
public final class MinimalIterable<E extends @Nullable Object> implements Iterable<E> {
  /** Returns an iterable whose iterator returns the given elements in order. */

    protected T doForward(String value) {
      return Enum.valueOf(enumClass, value);
    }

    @Override
    protected String doBackward(T enumValue) {
      return enumValue.name();
    }

    @Override
    public boolean equals(@Nullable Object obj) {
      if (obj instanceof StringConverter) {
        StringConverter<?> that = (StringConverter<?>) obj;
        return this.enumClass.equals(that.enumClass);
      }

        versionNo = null;

    }

    /**
     * Returns the default current page number.
     *
     * @return the default current page number (1)
     */
    protected int getDefaultCurrentPageNumber() {
        return DEFAULT_CURRENT_PAGE_NUMBER;
    }

    /**
     * Gets the total number of records across all pages.
     *
     * @return the total record count
     */

    }

    @Test
    @DisplayName("Test writeSetupWireFormat returns 0")
    void testWriteSetupWireFormat() {
        byte[] buffer = new byte[100];
        int result = response.writeSetupWireFormat(buffer, 0);

        assertEquals(0, result);
    }

    @Test
    @DisplayName("Test writeParametersWireFormat returns 0")
    void testWriteParametersWireFormat() {
        byte[] buffer = new byte[100];

     * Splits the given string into an array of substrings based on the specified regular expression
     * and returns a stream of those substrings.
     *
     * @param value the string to be split; if {@code null}, the method returns an empty stream
     * @param regex the regular expression to use for splitting the string
     * @return a stream of substrings resulting from splitting the input string, or an empty stream if the input is {@code null}
     */

    super(directed);
  }

  /** Returns a {@link NetworkBuilder} for building directed networks. */
  public static NetworkBuilder<Object, Object> directed() {
    return new NetworkBuilder<>(true);
  }

  /** Returns a {@link NetworkBuilder} for building undirected networks. */
  public static NetworkBuilder<Object, Object> undirected() {
    return new NetworkBuilder<>(false);
  }

  /**

        assertSame(session, session.acquire());
        verify(transport, times(1)).acquire();
        assertTrue(session.isInUse());
    }

    @Test
    @DisplayName("getSessionKey: throws when absent, returns when present")
    void testGetSessionKey() throws Exception {
        SmbSessionImpl session = newSession();

        // Absent key -> CIFSException