globalMinioDefaultRegion, serviceS3), "policy"),
				},
				"Policy": []string{"policy"},
			},
			expected: ErrNone,
		},
	}

	// Run each test case individually.
	for i, testCase := range testCases {
		_, code := doesPolicySignatureMatch(testCase.form)
		if code != testCase.expected {

pkg syscall (netbsd-arm64-cgo), type InterfaceMessage struct, Header IfMsghdr
pkg syscall (netbsd-arm64-cgo), type Iovec struct
pkg syscall (netbsd-arm64-cgo), type Iovec struct, Base *uint8
pkg syscall (netbsd-arm64-cgo), type Iovec struct, Len uint64
pkg syscall (netbsd-arm64-cgo), type IPv6MTUInfo struct
pkg syscall (netbsd-arm64-cgo), type IPv6MTUInfo struct, Addr RawSockaddrInet6

)

var errEtcdUnreachable = errors.New("etcd is unreachable, please check your endpoints")

func etcdErrToErr(err error, etcdEndpoints []string) error {
	if err == nil {
		return nil
	}
	switch err {
	case context.DeadlineExceeded:
		return fmt.Errorf("%w %s", errEtcdUnreachable, etcdEndpoints)
	default:
		return fmt.Errorf("unexpected error %w from etcd, please check your endpoints %s", err, etcdEndpoints)
	}
}

	{err: errObjectTampered, errCode: ErrObjectTampered},

	{err: nil, errCode: ErrNone},
	{err: errors.New("Custom error"), errCode: ErrInternalError}, // Case where err type is unknown.
}

func TestAPIErrCode(t *testing.T) {
	ctx := context.Background()
	for i, testCase := range toAPIErrorTests {
		errCode := toAPIErrorCode(ctx, testCase.err)

```Python hl_lines="11  14-16"
{!../../docs_src/sub_applications/tutorial001.py!}
```

### Mount the sub-application

In your top-level application, `app`, mount the sub-application, `subapi`.

In this case, it will be mounted at the path `/subapi`:

```Python hl_lines="11  19"
{!../../docs_src/sub_applications/tutorial001.py!}
```

### Check the automatic API docs

Now, run the `fastapi` command with your file:

You probably want to test the external provider once, but not necessarily call it for every test that runs.

In this case, you can override the dependency that calls that provider, and use a custom dependency that returns a mock user, only for your tests.

### Use the `app.dependency_overrides` attribute

		return fmt.Errorf("poolMeta: no data")
	}
	// Read header
	switch binary.LittleEndian.Uint16(data[0:2]) {
	case poolMetaFormat:
	default:
		return fmt.Errorf("poolMeta: unknown format: %d", binary.LittleEndian.Uint16(data[0:2]))
	}
	switch binary.LittleEndian.Uint16(data[2:4]) {
	case poolMetaVersion:
	default:
		return fmt.Errorf("poolMeta: unknown version: %d", binary.LittleEndian.Uint16(data[2:4]))
	}

 * methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change the
 * behavior of {@link #offer} which can lead to unexpected behavior. In this case, you should
 * override {@code offer} as well.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code

	if err == nil {
		t.Fatalf("should returns error but got nil")
	}
}

func TestReturningWithNullToZeroValues(t *testing.T) {
	dialect := DB.Dialector.Name()
	switch dialect {
	case "mysql", "sqlserver":
		// these dialects do not support the "returning" clause
		return
	default:
		// This user struct will leverage the existing users table, but override
		// the Name field to default to null.

# Bigger Applications - Multiple Files

If you are building an application or a web API, it's rarely the case that you can put everything in a single file.

**FastAPI** provides a convenience tool to structure your application while keeping all the flexibility.

/// info

If you come from Flask, this would be the equivalent of Flask's Blueprints.

///

## An example file structure

Let's say you have a file structure like this:

```