Using ScopedTempDir as the download directory used by the DownloadViaPost test.

chrome/browser/extensions/api/extension_action/browser_action_apitest.cc

 // Copyright (c) 2012 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.
 
 #include <stdint.h>
 
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/files/scoped_temp_dir.h"
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "chrome/browser/extensions/api/extension_action/extension_action_api.h"
 #include "chrome/browser/extensions/browser_action_test_util.h"
 #include "chrome/browser/extensions/extension_action.h"
 #include "chrome/browser/extensions/extension_action_icon_factory.h"
 #include "chrome/browser/extensions/extension_action_manager.h"
 #include "chrome/browser/extensions/extension_action_runner.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/extensions/extension_tab_util.h"
 #include "chrome/browser/extensions/extension_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_navigator_params.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/extensions/extension_process_policy.h"
+#include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/ui_test_utils.h"
+#include "components/prefs/pref_service.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/test/browser_test_utils.h"
 #include "content/public/test/content_browser_test_utils.h"
 #include "content/public/test/download_test_observer.h"
 #include "content/public/test/test_utils.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
@@ skipping 946 matching lines @@
 // works: No navigation, but download shelf visible + download goes through.
 //
 // Note - there is no "...ViaGet" flavour of this test, because we don't care
 // (yet) if GET succeeds with the download or not (it probably should succeed
 // for consistency with POST, but it always failed in M54 and before).  After
 // abandoing ShouldFork/OpenURL for all methods (not just for POST) [see comment
 // about https://crbug.com/646261 in ChromeContentRendererClient::ShouldFork]
 // GET should automagically start working for downloads.
 // TODO(lukasza): https://crbug.com/650694: Add a "Get" flavour of the test once
 // the download works both for GET and POST requests.
+IN_PROC_BROWSER_TEST_F(NavigatingExtensionPopupBrowserTest, DownloadViaPost) {
+  // Override the default downloads directory, so that the test can cleanup
+  // after itself.  This section is based on CreateAndSetDownloadsDirectory
+  // method defined in a few other source files with tests.
+  base::ScopedTempDir downloads_directory;
+  ASSERT_TRUE(downloads_directory.CreateUniqueTempDir());
+  browser()->profile()->GetPrefs()->SetFilePath(
+      prefs::kDownloadDefaultDirectory, downloads_directory.GetPath());
+  browser()->profile()->GetPrefs()->SetFilePath(
+      prefs::kSaveFileDefaultDirectory, downloads_directory.GetPath());
 
-// Disabled on Windows. See http://crbug.com/653856.
-#if defined(OS_WIN)
-#define MAYBE_DownloadViaPost DISABLED_DownloadViaPost
-#else
-#define MAYBE_DownloadViaPost DownloadViaPost
-#endif
-
-IN_PROC_BROWSER_TEST_F(NavigatingExtensionPopupBrowserTest,
-                       MAYBE_DownloadViaPost) {
+  // Setup monitoring of the downloads.
   content::DownloadTestObserverTerminal downloads_observer(
       content::BrowserContext::GetDownloadManager(browser()->profile()),
       1,  // == wait_count (only waiting for "download-test3.gif").
       content::DownloadTestObserver::ON_DANGEROUS_DOWNLOAD_FAIL);
 
   // Navigate to a URL that replies with
   // Content-Disposition: attachment; filename=...
   // header.
   GURL download_url(
       embedded_test_server()->GetURL("foo.com", "/download-test3.gif"));
   TestPopupNavigationViaPost(download_url, EXPECTING_NAVIGATION_FAILURE);
 
   // Verify that "download-test3.gif got downloaded.
   downloads_observer.WaitForFinished();
   EXPECT_EQ(0u, downloads_observer.NumDangerousDownloadsSeen());
   EXPECT_EQ(1u, downloads_observer.NumDownloadsSeenInState(
                     content::DownloadItem::COMPLETE));
+  EXPECT_TRUE(base::PathExists(downloads_directory.GetPath().AppendASCII(
+      "download-test3-attachment.gif")));

[Łukasz Anforowicz, 2016/10/07 23:32:03]

Inlining / having |downloads_directory| right here, also allows me add one more
simple test assert above.

 
   // The test verification below is applicable only to scenarios where the
   // download shelf is supported - on ChromeOS, instead of the download shelf,
   // there is a download notification in the right-bottom corner of the screen.
 #if !defined(OS_CHROMEOS)
   EXPECT_TRUE(browser()->window()->IsDownloadShelfVisible());
 #endif
 }
 
 }  // namespace
 }  // namespace extensions