core/modules/block/src/Tests/BlockTest.php                 |  4 +++-
 core/modules/file/src/Tests/DownloadTest.php               |  4 +++-
 core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php |  4 +++-
 .../page_cache/src/Tests/PageCacheTagsIntegrationTest.php  |  4 +++-
 core/modules/page_cache/src/Tests/PageCacheTest.php        | 14 ++++++++++----
 .../system/src/Tests/Ajax/AjaxFormPageCacheTest.php        |  4 +++-
 .../system/src/Tests/Cache/PageCacheTagsTestBase.php       |  4 +++-
 .../system/src/Tests/Form/FormStoragePageCacheTest.php     |  4 +++-
 core/modules/system/src/Tests/Session/SessionTest.php      |  4 +++-
 9 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/core/modules/block/src/Tests/BlockTest.php b/core/modules/block/src/Tests/BlockTest.php
index 8cdab7f..1ff3946 100644
--- a/core/modules/block/src/Tests/BlockTest.php
+++ b/core/modules/block/src/Tests/BlockTest.php
@@ -312,7 +312,9 @@ public function testBlockCacheTags() {
     $this->drupalLogout();
 
     // Enable page caching.
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 300);
+    $config->save();
 
     // Place the "Powered by Drupal" block.
     $block = $this->drupalPlaceBlock('system_powered_by_block', array('id' => 'powered', 'cache' => array('max_age' => 315360000)));
diff --git a/core/modules/file/src/Tests/DownloadTest.php b/core/modules/file/src/Tests/DownloadTest.php
index 87c4aa3..165a76a 100644
--- a/core/modules/file/src/Tests/DownloadTest.php
+++ b/core/modules/file/src/Tests/DownloadTest.php
@@ -58,7 +58,9 @@ public function testPrivateFileTransferWithPageCache() {
     // Turn on page caching and rerun the test.
     $this->assertTrue($this->container->get('module_installer')->install(['page_cache']), 'Page cache module installed.');
     $this->rebuildContainer();
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 300);
+    $config->save();
 
     $this->doPrivateFileTransferTest();
   }
diff --git a/core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php b/core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php
index 1960d0f..dba4cec 100644
--- a/core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php
+++ b/core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php
@@ -249,7 +249,9 @@ protected function enablePageCache() {
     // Turn on page caching and rerun the test.
     $this->assertTrue($this->container->get('module_installer')->install(['page_cache']), 'Page cache module installed.');
     $this->rebuildContainer();
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 300);
+    $config->save();
   }
 
 }
diff --git a/core/modules/page_cache/src/Tests/PageCacheTagsIntegrationTest.php b/core/modules/page_cache/src/Tests/PageCacheTagsIntegrationTest.php
index 8226c01..1d1b558 100644
--- a/core/modules/page_cache/src/Tests/PageCacheTagsIntegrationTest.php
+++ b/core/modules/page_cache/src/Tests/PageCacheTagsIntegrationTest.php
@@ -31,7 +31,9 @@ class PageCacheTagsIntegrationTest extends WebTestBase {
   protected function setUp() {
     parent::setUp();
 
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 300);
+    $config->save();
   }
 
   /**
diff --git a/core/modules/page_cache/src/Tests/PageCacheTest.php b/core/modules/page_cache/src/Tests/PageCacheTest.php
index 6c6fb06..0aef91f 100644
--- a/core/modules/page_cache/src/Tests/PageCacheTest.php
+++ b/core/modules/page_cache/src/Tests/PageCacheTest.php
@@ -36,7 +36,9 @@ protected function setUp() {
       ->set('page.front', 'test-page')
       ->save();
 
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 300);
+    $config->save();
   }
 
   /**
@@ -136,7 +138,9 @@ function testConditionalRequests() {
    * Tests cache headers.
    */
   function testPageCache() {
-    $this->config('system.performance')->set('response.gzip', 1)->save();
+    $config = $this->config('system.performance');
+    $config->set('response.gzip', 1);
+    $config->save();
 
     // Fill the cache.
     $this->drupalGet('system-test/set-header', array('query' => array('name' => 'Foo', 'value' => 'bar')));
@@ -204,7 +208,8 @@ public function testPageCacheWithoutVaryCookie() {
    */
   function testPageCompression() {
     $config = $this->config('system.performance');
-    $config->set('response.gzip', 1)->save();
+    $config->set('response.gzip', 1);
+    $config->save();
 
     // Fill the cache and verify that output is compressed.
     $this->drupalGet('', array(), array('Accept-Encoding: gzip,deflate'));
@@ -227,7 +232,8 @@ function testPageCompression() {
     $this->assertRaw('</html>', 'Page was not compressed.');
 
     // Disable compression mode.
-    $config->set('response.gzip', 0)->save();
+    $config->set('response.gzip', 0);
+    $config->save();
 
     // Verify if cached page is still available for a client with compression support.
     $this->drupalGet('', array(), array('Accept-Encoding: gzip,deflate'));
diff --git a/core/modules/system/src/Tests/Ajax/AjaxFormPageCacheTest.php b/core/modules/system/src/Tests/Ajax/AjaxFormPageCacheTest.php
index f58b08a..3e36515 100644
--- a/core/modules/system/src/Tests/Ajax/AjaxFormPageCacheTest.php
+++ b/core/modules/system/src/Tests/Ajax/AjaxFormPageCacheTest.php
@@ -25,7 +25,9 @@ class AjaxFormPageCacheTest extends AjaxTestBase {
   public function setUp() {
     parent::setUp();
 
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 300);
+    $config->save();
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Cache/PageCacheTagsTestBase.php b/core/modules/system/src/Tests/Cache/PageCacheTagsTestBase.php
index af738ad..7909300 100644
--- a/core/modules/system/src/Tests/Cache/PageCacheTagsTestBase.php
+++ b/core/modules/system/src/Tests/Cache/PageCacheTagsTestBase.php
@@ -35,7 +35,9 @@ protected function setUp() {
     parent::setUp();
 
     // Enable page caching.
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 3600);
+    $config->save();
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Form/FormStoragePageCacheTest.php b/core/modules/system/src/Tests/Form/FormStoragePageCacheTest.php
index 75bd207..bac12db 100644
--- a/core/modules/system/src/Tests/Form/FormStoragePageCacheTest.php
+++ b/core/modules/system/src/Tests/Form/FormStoragePageCacheTest.php
@@ -27,7 +27,9 @@ class FormStoragePageCacheTest extends WebTestBase {
   protected function setUp() {
     parent::setUp();
 
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 300);
+    $config->save();
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Session/SessionTest.php b/core/modules/system/src/Tests/Session/SessionTest.php
index e2c38f9..c5a7220 100644
--- a/core/modules/system/src/Tests/Session/SessionTest.php
+++ b/core/modules/system/src/Tests/Session/SessionTest.php
@@ -146,7 +146,9 @@ function testEmptyAnonymousSession() {
     // The same behavior is expected when caching is enabled.
     $this->assertTrue($this->container->get('module_installer')->install(['page_cache']), 'Page cache module installed.');
     $this->rebuildContainer();
-    $this->config('system.performance')->set('cache.page.max_age', 300)->save();
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 300);
+    $config->save();
     $this->drupalGet('');
     $this->assertSessionCookie(FALSE);
     // @todo Reinstate when REQUEST and RESPONSE events fire for cached pages.