is not available, instead of erroring out, the dependency result will
                be `None`.

                This is useful when you want to have optional authentication.

                It is also useful when you want to have authentication that can be
                provided in one of multiple optional ways (for example, in HTTP Basic
                authentication or in an HTTP Bearer token).

	a := arena.NewArena()
	defer a.Free()

	tt := arena.New[T1](a)
	tt.n = 1

	ts := arena.MakeSlice[T1](a, 99, 100)
	if len(ts) != 99 {
		t.Errorf("Slice() len = %d, want 99", len(ts))
	}
	if cap(ts) != 100 {
		t.Errorf("Slice() cap = %d, want 100", cap(ts))
	}
	ts[1].n = 42
}

func TestSmokeLarge(t *testing.T) {
	a := arena.NewArena()
	defer a.Free()
	for i := 0; i < 10*64; i++ {
		_ = arena.New[T2](a)

		t.Fatalf("Output didn't match for '%s %s'\n got %v\nwant: %v", cmd.Name(), strings.Join(c.args, " "), output, c.expectedString)
	}

	if c.wantException {
		if fErr == nil {
			t.Fatalf("Wanted an exception for 'istioctl %s', didn't get one, output was %q",
				strings.Join(c.args, " "), output)
		}
	} else {
		if fErr != nil {

     * configuration). This is useful when you want to force the user to use common POM elements rather than plugin
     * configurations, as in the case where you want to use the artifact's final name as a parameter. In this case, you
     * want the user to modify <code>&lt;build&gt;&lt;finalName/&gt;&lt;/build&gt;</code> rather than specifying a value

	if domain := S3.String(); domain != Domain {
		t.Errorf("S3's string method returns wrong domain: got '%s' - want '%s'", domain, Domain)
	}
}

func TestSSECString(t *testing.T) {
	const Domain = "SSE-C"
	if domain := SSEC.String(); domain != Domain {
		t.Errorf("SSEC's string method returns wrong domain: got '%s' - want '%s'", domain, Domain)
	}
}

var ssecUnsealObjectKeyTests = []struct {
	Headers        http.Header

In some cases, you may want to override the logic used by the `Request` and `APIRoute` classes.

In particular, this may be a good alternative to logic in a middleware.

For example, if you want to read or manipulate the request body before it is processed by your application.

/// danger

This is an "advanced" feature.

If you are just starting with **FastAPI** you might want to skip this section.

///

  /**
   * No-op null-pointer test for {@link LongAdder} to override the {@link PackageSanityTests}
   * version, which checks package-private methods that we don't want to have to annotate as {@code
   * Nullable} because we don't want diffs from jsr166e.
   */
  public void testNulls() {}

  public void testOverflows() {
    LongAdder longAdder = new LongAdder();
    longAdder.add(Long.MAX_VALUE);

# Development - Contributing

First, you might want to see the basic ways to [help FastAPI and get help](help-fastapi.md){.internal-link target=_blank}.

## Developing

If you already cloned the <a href="https://github.com/fastapi/fastapi" class="external-link" target="_blank">fastapi repository</a> and you want to deep dive in the code, here are some guidelines to set up your environment.

### Virtual environment

But you are not restricted to using some specific data model, class or type.

Do you want to have an `id` and `email` and not have any `username` in your model? Sure. You can use these same tools.

Do you want to just have a `str`? Or just a `dict`? Or a database class model instance directly? It all works the same way.

    "version" that omits the class to avoid conflicts with the copy in Guava
    itself. The idea is:

    - If users want only ListenableFuture, they depend on listenablefuture-1.0.

    - If users want all of Guava, they depend on guava, which, as of Guava
    27.0, depends on
    listenablefuture-9999.0-empty-to-avoid-conflict-with-guava. The 9999.0-...