Instead, you want to provide a different dependency that will be used only during tests (possibly only some specific tests), and will provide a value that can be used where the value of the original dependency was used.

### 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.

	"github.com/google/uuid"
)

var testUUID = uuid.MustParse("f5c58c61-7175-4018-ab5e-a94fe9c2de4e")

func BenchmarkCrcHash(b *testing.B) {
	cases := []struct {
		key int
	}{
		{16},
		{64},
		{128},
		{256},
		{512},
		{1024},
	}
	for _, testCase := range cases {
		key := randString(testCase.key)
		b.Run("", func(b *testing.B) {
			b.SetBytes(1024)
			b.ReportAllocs()
			b.ResetTimer()
			for b.Loop() {

///

## Use cases { #use-cases }

Some use cases include:

* Converting non-JSON request bodies to JSON (e.g. <a href="https://msgpack.org/index.html" class="external-link" target="_blank">`msgpack`</a>).
* Decompressing gzip-compressed request bodies.
* Automatically logging all request bodies.

## Handling custom request body encodings { #handling-custom-request-body-encodings }

Of course, there are some cases where there's no problem in running the previous steps multiple times, in that case, it's a lot easier to handle.

/// tip

Also, keep in mind that depending on your setup, in some cases you **might not even need any previous steps** before starting your application.

In that case, you wouldn't have to worry about any of this. 🤷

///

You probably read before that you can set a default [Response Status Code](../tutorial/response-status-code.md){.internal-link target=_blank}.

But in some cases you need to return a different status code than the default.

## Use case { #use-case }

For example, imagine that you want to return an HTTP status code of "OK" `200` by default.

Those parameters are what **FastAPI** will use to "solve" the dependency.

In both cases, it will have:

* An optional `q` query parameter that is a `str`.
* A `skip` query parameter that is an `int`, with a default of `0`.
* A `limit` query parameter that is an `int`, with a default of `100`.

In both cases the data will be converted, validated, documented on the OpenAPI schema, etc.

## Use it { #use-it }

				return
			}
		}
	}

	for idx, ownField := range ownForeignFields {
		joinFieldName := cases.Title(language.Und, cases.NoLower).String(schema.Name) + ownField.Name
		if len(joinForeignKeys) > idx {
			joinFieldName = cases.Title(language.Und, cases.NoLower).String(joinForeignKeys[idx])
		}

		ownFieldsMap[joinFieldName] = ownField
		fieldsMap[joinFieldName] = ownField

		},
		{bucketName: "a", objName: "obj", PartID: 1, expectedError: fmt.Errorf("%s", "Bucket name invalid: a")},
		// Test case - 5.
		// Case with invalid object names.
		{bucketName: bucket, PartID: 1, expectedError: fmt.Errorf("%s", "Object name invalid: minio-bucket/")},
		// Test case - 6.
		// Valid object and bucket names but non-existent bucket.

   *
   * {@snippet :
   * // Falling back to a zero counter in case an exception happens when processing the RPC to fetch
   * // counters.
   * ListenableFuture<Integer> faultTolerantFuture =
   *     fetchCounters().catching(FetchException.class, x -> 0, directExecutor());
   * }
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See

# Dependencies in path operation decorators { #dependencies-in-path-operation-decorators }

In some cases you don't really need the return value of a dependency inside your *path operation function*.

Or the dependency doesn't return a value.

But you still need it to be executed/solved.

For those cases, instead of declaring a *path operation function* parameter with `Depends`, you can add a `list` of `dependencies` to the *path operation decorator*.