## Mounting a **FastAPI** application

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

### Top-level application

First, create the main, top-level, **FastAPI** application, and its *path operations*:

```Python hl_lines="3  6-8"
{!../../docs_src/sub_applications/tutorial001.py!}
```

def test_path_foobar():
    response = client.get("/path/foobar")
    assert response.status_code == 200
    assert response.json() == "foobar"


def test_path_str_foobar():
    response = client.get("/path/str/foobar")
    assert response.status_code == 200
    assert response.json() == "foobar"


def test_path_str_42():
    response = client.get("/path/str/42")
    assert response.status_code == 200

   * href="https://url.spec.whatwg.org/#syntax-url-path-segment">URL path segments</a>. The returned
   * escaper escapes all non-ASCII characters, even though <a
   * href="https://url.spec.whatwg.org/#url-code-points">many of these are accepted in modern
   * URLs</a>. (<a href="https://url.spec.whatwg.org/#path-state">If the escaper were to leave these

#   * -classpath
#   * -D...appname settings
#   * --module-path (only if needed)
#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.

# For Cygwin or MSYS, switch paths to Windows format before running java
if "$cygwin" || "$msys" ; then
    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )

    JAVACMD=$( cygpath --unix "$JAVACMD" )

@Warmup(iterations = 3)
@Measurement(time = 10)
public class Xpp3DomPerfTest {
    @State(Scope.Benchmark)
    public static class AdditionState {
        List<Path> poms;

        @Setup(Level.Iteration)
        public void setUp() throws IOException {
            Path userHome = Paths.get(System.getProperty("user.home"));
            poms = Files.walk(userHome.resolve(".m2/repository/org/apache/maven"))

        assertArgumentNotEmpty("path", path);

        return getResourceNoException(path) != null;
    }

    /**
     * コンテキストクラスローダからプロパティファイルをロードして返します。
     *
     * @param path
     *            プロパティファイルのパス。{@literal null}や空文字列であってはいけません
     * @return プロパティファイル
     */
    public static Properties getProperties(final String path) {

    PluginsMetadata(PluginInfo pluginInfo, Date timestamp) {
        super(createRepositoryMetadata(pluginInfo), (Path) null, timestamp);
        this.pluginInfo = pluginInfo;
    }

    PluginsMetadata(PluginInfo pluginInfo, Path path, Date timestamp) {
        super(createRepositoryMetadata(pluginInfo), path, timestamp);
        this.pluginInfo = pluginInfo;
    }

        return Collections.unmodifiableCollection(result);
    }

    @Override
    public void attachArtifact(Project project, ProducedArtifact artifact, Path path) {
        nonNull(project, "project");
        nonNull(artifact, "artifact");
        nonNull(path, "path");
        if (artifact.getGroupId().isEmpty()
                || artifact.getArtifactId().isEmpty()
                || artifact.getBaseVersion().asString().isEmpty()) {

        Response response = checkMethodBase(body).get(getApiPath() + "/" + path);
        // logger.debug(response.asString());
        return response;
    }

    protected Response checkPutMethod(final Map<String, Object> body, final String path) {
        Response response = checkMethodBase(body).put(getApiPath() + "/" + path);
        // logger.debug(response.asString());

            ]
        }
    )


@needs_py39
def test_post_files(tmp_path, app: FastAPI):
    path = tmp_path / "test.txt"
    path.write_bytes(b"<file content>")
    path2 = tmp_path / "test2.txt"
    path2.write_bytes(b"<file content2>")

    client = TestClient(app)
    with path.open("rb") as file, path2.open("rb") as file2:
        response = client.post(
            "/files/",
            files=(