Stop using SpawnedTestServer in DownloadContentTest.*

content/public/test/test_download_request_handler.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_PUBLIC_TEST_TEST_DOWNLOAD_REQUEST_HANDLER_H_

[sky, 2015/12/01 21:58:50]

Is there a reason this class needs to live in content? Can't it live next to the
only that that is using it?

[asanka, 2015/12/02 15:41:34]

We want to also switch over //chrome/browser/download/download_browsertest.cc to
use this when we add automatic resumption in //chrome. Automatic resumption
relies on a number of signals (user preferences, connection type changes, etc..)
that are exposed at //chrome and not //content.

+#define CONTENT_PUBLIC_TEST_TEST_DOWNLOAD_REQUEST_HANDLER_H_
+
+#include <stdint.h>
+#include <queue>
+
+#include "base/callback_forward.h"
+#include "base/files/file.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/non_thread_safe.h"
+#include "net/base/completion_callback.h"
+#include "net/base/net_errors.h"
+#include "net/http/http_byte_range.h"
+#include "net/http/http_response_headers.h"
+#include "net/http/http_util.h"
+#include "net/url_request/url_request_job.h"
+#include "url/gurl.h"
+
+namespace content {
+
+// A request handler that can be used to mock the behavior of a URLRequestJob
+// for a download.
+//
+// Testing of download interruption scenarios typically involve simulating
+// errors that occur:
+// 1. On the client, prior to the request being sent out,
+// 2. On the network, between the client and the server,
+// 3. On the server,
+// 4. Back on the client, while writing the response to disk,
+// 5. On the client, after the response has been written to disk.
+//
+// This test class is meant to help test failures in #2 and #3 above. The test
+// implementation depends on content::BrowserThread and assumes that the
+// thread identified by BrowserThread::IO is the network task runner thread.
+//
+// TestDownloadRequestHandler can be used on any thread as long as it is used
+// and destroyed on the same thread it was constructed on.
+//
+// To use the test request handler:
+//
+//  // Define the request handler. Note that initialization of the
+//  // TestDownloadRequestHandler object immediately registers it as well and is
+//  // a blocking operation.
+//  TestDownloadRequestHandler request_handler;
+//
+//  // Set up parameters for the partial request handler.
+//  TestDownloadRequestHandler::Parameters parameters;
+//
+//  // Inject an error at offset 100.
+//  parameters.injected_errors.push(TestDownloadRequestHandler::InjectedError(
+//      100, net::ERR_CONNECTION_RESET));
+//
+//  // Start serving.
+//  request_handler.StartServing(parameters);
+//
+// At this point, you can initiate a URLRequest for request_handler.url(). The
+// request will fail when offset 100 is reached with the error specified above.
+class TestDownloadRequestHandler : public base::NonThreadSafe {
+ public:
+  // OnStartHandler can be used to intercept the Start() event of a new
+  // URLRequest. Set it as the |on_start_handler| member of Parameters below.
+  //
+  // The callback is invoked on the thread on which TestDownloadRequestHandler
+  // was created. Once the callback has a response ready, it can invoke the
+  // OnStartResponseCallback object. The latter can be invoked on any thread and
+  // will post back to the IO thread to continue with processing the Start()
+  // event.
+  //
+  // The parameters to the OnStartResponseCallback are:
+  //
+  // * a |const std::string&| containing the headers to be sent in response to
+  //   the request. The headers should be formatted according to the
+  //   requirements of net::HttpUtil::AssembleRawHeaders(). The headers are only
+  //   used if the |net::Error| parameters is net::OK.
+  //
+  // * a |net::Error| indicating the result of the operation. If this parameters
+  //   is not net::OK, then that error value is set as the result of the Start()
+  //   operation. The headers are ignored in this case.
+  //
+  //   If the error is net::OK, and the headers are empty, then the request is
+  //   handled based on the remaining parameters in |Parameters|.
+  using OnStartResponseCallback =
+      base::Callback<void(const std::string&, net::Error)>;
+
+  using OnStartHandler = base::Callback<void(const net::HttpRequestHeaders&,
+                                             const OnStartResponseCallback&)>;
+
+  // An injected error.
+  struct InjectedError {
+    InjectedError(int64_t offset, net::Error error);
+
+    int64_t offset;
+    net::Error error;
+  };
+
+  // Parameters used by StartServing().
+  struct Parameters {
+    // Constructs a Parameters structure using the default constructor, but with
+    // the addition of a net::ERR_CONNECTION_RESET which will be triggered at
+    // byte offset (filesize / 2).
+    static Parameters WithSingleInterruption();
+
+    // The default constructor initializes the parameters for serving a 100 KB
+    // resource with no interruptions. The response contains an ETag and a
+    // Last-Modified header and the server supports byte range requests.
+    Parameters();
+
+    // Parameters is expected to be copyable and moveable.
+    Parameters(Parameters&&);
+    Parameters(const Parameters&);
+    Parameters& operator=(Parameters&&);
+    Parameters& operator=(const Parameters&);
+    ~Parameters();
+
+    // Clears the errors in injected_errors.
+    void ClearInjectedErrors();
+
+    // Contents of the ETag header field of the response.  No Etag header is
+    // sent if this field is empty.
+    std::string etag;
+
+    // Contents of the Last-Modified header field of the response. No
+    // Last-Modified header is sent if this field is empty.
+    std::string last_modified;
+
+    // The Content-Type of the response. No Content-Type header is sent if this
+    // field is empty.
+    std::string content_type;
+
+    // The total size of the entity. If the entire entity is requested, then
+    // this would be the same as the value returned in the Content-Length
+    // header.
+    int64_t size;
+
+    // Seed for the pseudo-random sequence that defines the response body
+    // contents. The seed is with GetPatternBytes() to generate the body of the
+    // response.
+    int pattern_generator_seed;
+
+    // If true, the response contains a 'Accept-Ranges: bytes' header.
+    bool support_byte_ranges;
+
+    // If on_start_handler is valid, it will be invoked when a new request is
+    // received. See details about the OnStartHandler above.
+    OnStartHandler on_start_handler;
+
+    // Errors to be injected. Each injected error is defined by an offset and an
+    // error. Request handler will successfully fulfil requests to read up to
+    // |offset|. An attempt to read the byte at |offset| will result in the
+    // error defined by the InjectErrors object.
+    //
+    // If a read spans the range containing |offset|, then the portion of the
+    // request preceding |offset| will succeed. The next read would start at
+    // |offset| and hence would result in an error.
+    //
+    // E.g.: injected_errors.push(InjectedError(100, ERR_CONNECTION_RESET));
+    //
+    //    A network read for 1024 bytes at offset 0 would result in successfully
+    //    reading 100 bytes (bytes with offset 0-99). The next read would,
+    //    therefore, start at offset 100 and would result in
+    //    ERR_CONNECTION_RESET.
+    //
+    // Injected errors are processed in the order in which they appear in
+    // |injected_errors|. When handling a network request for the range [S,E]
+    // (inclusive), all events in |injected_errors| where |offset| is less than
+    // S will be ignored. The first event remaining will trigger an error once
+    // the sequence of reads proceeds to a point where its |offset| is included
+    // in [S,E].
+    //
+    // This implies that |injected_errors| must be specified in increasing order
+    // of |offset|. I.e. |injected_errors| must be sorted by |offset|.
+    //
+    // Errors at relative offset 0 are ignored for a partial request. I.e. If
+    // the request is for the byte range 100-200, then an error at offset 100
+    // will not trigger. This is done so that non-overlapping continuation
+    // attempts don't require resetting parameters to succeed.
+    //
+    // E.g.: If the caller injects an error at offset 100, then a request for
+    // the entire entity will fail after reading 100 bytes (offsets 0 through
+    // 99). A subsequent request for byte range "100-" (offsets 100 through EOF)
+    // will succeed since the error at offset 100 is ignored.
+    //
+    // Notes:
+    //
+    // * Distinctions about which read requests signal the error is often only
+    //   important at the //net layer. From //content, it would appear that 100
+    //   bytes were read and then request failed with ERR_CONNECTION_RESET.
+    std::queue<InjectedError> injected_errors;
+  };
+
+  // Details about completed requests returned by GetCompletedRequestInfo().
+  struct CompletedRequest {
+    // Count of bytes read by the client of the URLRequestJob. This counts the
+    // number of bytes of the entity that was transferred *after* content
+    // decoding is complete.
+    int64_t transferred_byte_count = -1;
+
+    net::HttpRequestHeaders request_headers;
+  };
+
+  using CompletedRequests = std::vector<CompletedRequest>;
+
+  // Registers a request handler at the default URL. Call url() to determine the
+  // URL.
+  //
+  // Notes:
+  // * This constructor is only meant to be used for convenience when the caller
+  //   is not interested in the URL used for interception. The URL used is
+  //   generated at run time and should not be assumed to be the same across
+  //   different runs of the same test.
+  //
+  // * Initialization of the handler synchronously runs a task on the
+  //   BrowserThread::IO thread using a nested message loop. Only construct an
+  //   instance of this object after browser threads have been initialized.
+  TestDownloadRequestHandler();
+
+  // Similar to the default constructor, but registers the handler at |url|.
+  //
+  // Notes:
+  // * The behavior is undefined if more than one TestDownloadRequestHandler is
+  //   registered for the same URL.
+  TestDownloadRequestHandler(const GURL& url);
+
+  // Destroys and posts a task to the IO thread to dismantle the registered URL
+  // request interceptor. Does not wait for the task to return.
+  ~TestDownloadRequestHandler();
+
+  // Returns the URL that this instance is intercepting URLRequests for.
+  const GURL& url() const { return url_; }
+
+  // Start responding to URLRequests for url() with responses based on
+  // |parameters|.
+  //
+  // This method invocation posts a task to the IO thread to update the
+  // URLRequestInterceptor with the new parameters and returns immediately. URL
+  // interception won't be updated until the posted task executes. The method
+  // returns without waiting for the posted task to complete.
+  //
+  // Calling this method does not affect URLRequests that have already started.
+  // The new parameters will only be used to respond to new URLRequests that are
+  // starting.
+  //
+  // StartServing() can be called multiple times to change the operating
+  // parameters of the current URL interceptor.
+  void StartServing(const Parameters& parameters);
+
+  // Start responding to URLRequests for url() with a static response
+  // containing the headers in |headers|.
+  //
+  // The format of |headers| should comply with the requirements for
+  // net::HttpUtil::AssembleRawHeaders().
+  void StartServingStaticResponse(const base::StringPiece& headers);
+
+  // Get the list of requests that have already completed.
+  //
+  // This method posts a task to the IO thread to collect the list of completed
+  // requests and waits for the task to complete.
+  //
+  // Requests that are currently in progress will not be reflected in
+  // |requests|.
+  void GetCompletedRequestInfo(CompletedRequests* requests);
+
+  // Generate a pseudo random pattern.
+  //
+  // |seed| is the seed for the pseudo random sequence.  |offset| is the byte
+  // offset into the sequence.  |length| is a count of bytes to generate.
+  // |data| receives the generated bytes and should be able to store |length|
+  // bytes.
+  //
+  // The pattern has the following properties:
+  //
+  // * For a given |seed|, the entire sequence of bytes is fixed. Any
+  //   subsequence can be generated by specifying the |offset| and |length|.
+  //
+  // * The sequence is aperiodic (at least for the first 1M bytes).
+  //
+  // * |seed| is chaotic. Different seeds produce "very different" data. This
+  //   means that there's no trivial mapping between sequences generated using
+  //   two distinct seeds.
+  //
+  // These properties make the generated bytes useful for testing partial
+  // requests where the response may need to be built using a sequence of
+  // partial requests.
+  //
+  // Note: Don't use this function to generate a cryptographically secure
+  // pseudo-random sequence.
+  static void GetPatternBytes(int seed, int64 offset, int length, char* data);
+
+ private:
+  class Interceptor;
+  class PartialResponseJob;
+
+  GURL url_;
+  base::WeakPtr<Interceptor> interceptor_;
+  DISALLOW_COPY_AND_ASSIGN(TestDownloadRequestHandler);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_TEST_TEST_DOWNLOAD_REQUEST_HANDLER_H_