## What is "Dependency Injection" { #what-is-dependency-injection }

**"Dependency Injection"** means, in programming, that there is a way for your code (in this case, your *path operation functions*) to declare things that it requires to work and use: "dependencies".

And then, that system (in this case **FastAPI**) will take care of doing whatever is needed to provide your code with those needed dependencies ("inject" the dependencies).

        assertFalse(transaction.hasMoreElements(), "hasMoreElements should be false when all data is sent");
    }

    @Test
    @DisplayName("Test transaction with large data requires multiple elements")
    void testLargeDataMultipleElements() {
        // Set large amounts that won't fit in one buffer
        transaction.maxBufferSize = 100;
        transaction.setParameterBytesWritten(200);

            try {
                principal = getAuthenticator().authenticate(request, spnegoResponse);
                if (logger.isDebugEnabled()) {
                    logger.debug("principal: {}", principal);
                }
            } catch (final Exception e) {
                final String msg = "Failed to process Authorization Header: " + request.getHeader(Constants.AUTHZ_HEADER);
                if (logger.isDebugEnabled()) {

        assertEquals(1234, timeout);
    }

    @Test
    @DisplayName("getResponseTimeout falls back to config for non-SMB requests")
    void getResponseTimeout_default() {
        // Arrange
        Request req = mock(Request.class);
        when(cfg.getResponseTimeout()).thenReturn(2222);

        // Act & Assert
        assertEquals(2222, transport.getResponseTimeout(req));
    }

    @Test

is widely used on most Java projects within Google, and widely used by many
other companies as well.



Guava comes in two flavors:

*   The JRE flavor requires JDK 1.8 or higher.
*   If you need support for Android, use
    [the Android flavor](https://github.com/google/guava/wiki/Android). You can
    find the Android Guava source in the [`android` directory].

Let's start with a simple FastAPI application:

{* ../../docs_src/generate_clients/tutorial001_py39.py hl[7:9,12:13,16:17,21] *}

Notice that the *path operations* define the models they use for request payload and response payload, using the models `Item` and `ResponseMessage`.

### API Docs { #api-docs }

// multipart upload is a multipart upload that has been initiated,
// using the Initiate Multipart Upload request, but has not yet been
// completed or aborted. This operation returns at most 1,000 multipart
// uploads in the response.
func (api objectAPIHandlers) ListMultipartUploadsHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "ListMultipartUploads")

	defer logger.AuditLog(ctx, w, r, mustGetClaimsFromToken(r))

It is designed to have functions that receive two parameters, one "request" and one "response". Then you "read" parts from the request, and "write" parts to the response. Because of this design, it is not possible to declare request parameters and bodies with standard Python type hints as function parameters.

          .Builder()
          .code(101)
          .message("OK")
          .request(Request.Builder().url(url).build())
          .headers(responseHeaders!!)
          .protocol(Protocol.HTTP_1_1)
          .build()
      webSocket =
        RealWebSocket(
          taskFaker.taskRunner,
          response.request,
          listener,
          random!!,
          pingIntervalMillis.toLong(),

        }
    }

    /**
     * Processes a storage request with timeout management.
     * @param uri the URI to process
     * @param includeContent whether to include the actual content in the response
     * @return the response data for the request
     * @throws CrawlingAccessException if an error occurs while processing the request
     */