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.

     *         If all functions return null, the composite function returns null.
     *
     * @throws NullPointerException if the input collection is null or contains null elements.
     */
    static Function<String, String> chain(Collection<? extends Function<String, String>> functions) {
        return s -> {
            for (Function<String, String> function : functions) {
                String v = function.apply(s);

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

    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);

import static com.google.common.collect.Maps.transformValues;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import java.util.SortedMap;

/**
 * Tests for {@link Maps#transformValues(SortedMap, Function)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

import static com.google.common.collect.Maps.transformValues;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import java.util.Map;

/**
 * Tests for {@link Maps#transformValues(Map, Function)}.
 *
 * @author Isaac Shum
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

import static com.google.common.collect.Maps.transformValues;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import java.util.Map;

/**
 * Tests for {@link Maps#transformValues(Map, Function)}.
 *
 * @author Isaac Shum
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

  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

You can define event handlers (functions) that need to be executed before the application starts up, or when the application is shutting down.

These functions can be declared with `async def` or normal `def`.

### `startup` event

To add a function that should be run before the application starts, declare it with the event `"startup"`:

// and other runtime functions while identifying leaks.
var ignoredStackFns = []string{
	"",
	// Below are the stacks ignored by the upstream leaktest code.
	"testing.Main(",
	"testing.tRunner(",
	"testing.tRunner(",
	"runtime.goexit",
	"created by runtime.gc",
	// ignore the snapshot function.
	// since the snapshot is taken here the entry will have the current function too.