final HashFunction[] functions;

  AbstractCompositeHashFunction(HashFunction... functions) {
    for (HashFunction function : functions) {
      checkNotNull(function);
    }
    this.functions = functions;
  }

  /**
   * Constructs a {@code HashCode} from the {@code Hasher} objects of the functions. Each of them

                Map.of("_default", List.of("QUERY1")),...

As dependencies will also be called by **FastAPI** (the same as your *path operation functions*), the same rules apply while defining your functions.

You can use `async def` or normal `def`.

And you can declare dependencies with `async def` inside of normal `def` *path operation functions*, or `def` dependencies inside of `async def` *path operation functions*, etc.

It doesn't matter. **FastAPI** will know what to do.

/// note

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Let's look at how we can make that work.

## pytest.mark.anyio

If we want to call asynchronous functions in our tests, our test functions have to be asynchronous. AnyIO provides a neat plugin for this, that allows us to specify that some test functions are to be called asynchronously.

## HTTPX

Even if your **FastAPI** application uses normal `def` functions instead of `async def`, it is still an `async` application underneath.

    /**
     * Creates a composite function from a collection of functions.
     *
     * @param functions A collection of functions, each taking a String as input and returning a String.
     * @return A function that applies each function in the collection in order until a non-null result is found.
     *         If all functions return null, the composite function returns null.
     *

  }

  @Override
  protected Map<String, String> makePopulatedMap() {
    Map<String, Integer> underlying = Maps.newHashMap();
    underlying.put("a", 1);
    underlying.put("b", 2);
    underlying.put("c", 3);
    return transformValues(
        new UnmodifiableIteratorMap<String, Integer>(underlying), Functions.toStringFunction());
  }

    return transformValues(Maps.<String, String>newHashMap(), Functions.<String>identity());
  }

  @Override
  protected Map<String, String> makePopulatedMap() {
    Map<String, Integer> underlying = Maps.newHashMap();
    underlying.put("a", 1);
    underlying.put("b", 2);
    underlying.put("c", 3);
    return transformValues(underlying, Functions.toStringFunction());
  }

    Map<String, String> map =
        transformValues(ImmutableMap.<String, Integer>of(), Functions.toStringFunction());
    assertMapsEqual(Maps.newHashMap(), map);
  }

  public void testTransformSingletonMapEquality() {
    Map<String, String> map =
        transformValues(ImmutableMap.of("a", 1), Functions.toStringFunction());
    Map<String, String> expected = ImmutableMap.of("a", "1");
    assertMapsEqual(expected, map);

            ArrayListMultimap.<String, Integer>create(), Functions.<Integer>identity())
        .asMap();
  }

  @Override
  protected Map<String, Collection<Integer>> makePopulatedMap() {
    ListMultimap<String, Integer> delegate = ArrayListMultimap.create();
    populate(delegate);
    return Multimaps.transformValues(delegate, Functions.<Integer>identity()).asMap();
  }