Optimization: do not try to load non-existent next page.

- Includes tests.

module/VuFind/src/VuFind/Controller/Plugin/ResultScroller.php

@@ -171,9 +171,11 @@ class ResultScroller extends AbstractPlugin
      */
     protected function fetchNextPage($retVal, $lastSearch, $pos)
     {
-        // if the next page has not been fetched, then
-        // fetch the next page
-        if ($this->data->nextIds == null) {
+        // if the current page is NOT the last page, and the next page has not been
+        // fetched, then fetch the next page
+        if ($this->data->page < ceil($this->data->total / $this->data->limit)
+            && $this->data->nextIds == null
+        ) {
             $this->data->nextIds = $this->fetchPage(
                 $lastSearch, $this->data->page + 1
             );

module/VuFind/tests/unit-tests/src/VuFindTest/Controller/Plugin/ResultScrollerTest.php

@@ -42,6 +42,13 @@ use VuFindTest\Unit\TestCase as TestCase;
  */
 class ResultScrollerTest extends TestCase
 {
+    /**
+     * Cache for record driver mocks.
+     *
+     * @var array
+     */
+    protected $recordDrivers = array();
+
     /**
      * Test disabled behavior
      *
@@ -58,6 +65,78 @@ class ResultScrollerTest extends TestCase
         $this->assertEquals($expected, $plugin->getScrollData($this->getMockRecordDriver('foo')));
     }
 
+    /**
+     * Test scrolling for a record in the middle of the page
+     *
+     * @return void
+     */
+    public function testScrollingInMiddleOfPage()
+    {
+        $results = $this->getMockResults(1, 10, 10);
+        $plugin = $this->getMockResultScroller();
+        $plugin->expects($this->any())->method('restoreLastSearch')->will($this->returnValue($results));
+        $this->assertTrue($plugin->init($results));
+        $expected = array(
+            'previousRecord'=>'VuFind|4', 'nextRecord'=>'VuFind|6',
+            'currentPosition'=>5, 'resultTotal'=>10
+        );
+        $this->assertEquals($expected, $plugin->getScrollData($this->getMockRecordDriver(5)));
+    }
+
+    /**
+     * Test scrolling for a record at the start of the first page
+     *
+     * @return void
+     */
+    public function testScrollingAtStartOfFirstPage()
+    {
+        $results = $this->getMockResults(1, 10, 10);
+        $plugin = $this->getMockResultScroller();
+        $plugin->expects($this->any())->method('restoreLastSearch')->will($this->returnValue($results));
+        $this->assertTrue($plugin->init($results));
+        $expected = array(
+            'previousRecord'=>null, 'nextRecord'=>'VuFind|2',
+            'currentPosition'=>1, 'resultTotal'=>10
+        );
+        $this->assertEquals($expected, $plugin->getScrollData($this->getMockRecordDriver(1)));
+    }
+
+    /**
+     * Test scrolling for a record at the end of the last page (single-page example)
+     *
+     * @return void
+     */
+    public function testScrollingAtEndOfLastPage()
+    {
+        $results = $this->getMockResults(1, 10, 10);
+        $plugin = $this->getMockResultScroller();
+        $plugin->expects($this->any())->method('restoreLastSearch')->will($this->returnValue($results));
+        $this->assertTrue($plugin->init($results));
+        $expected = array(
+            'previousRecord'=>'VuFind|9', 'nextRecord'=>null,
+            'currentPosition'=>10, 'resultTotal'=>10
+        );
+        $this->assertEquals($expected, $plugin->getScrollData($this->getMockRecordDriver(10)));
+    }
+
+    /**
+     * Test scrolling for a record at the end of the last page (multi-page example)
+     *
+     * @return void
+     */
+    public function testScrollingAtEndOfLastPageInMultiPageScenario()
+    {
+        $results = $this->getMockResults(2, 10, 17);
+        $plugin = $this->getMockResultScroller();
+        $plugin->expects($this->any())->method('restoreLastSearch')->will($this->returnValue($results));
+        $this->assertTrue($plugin->init($results));
+        $expected = array(
+            'previousRecord'=>'VuFind|16', 'nextRecord'=>null,
+            'currentPosition'=>17, 'resultTotal'=>17
+        );
+        $this->assertEquals($expected, $plugin->getScrollData($this->getMockRecordDriver(17)));
+    }
+
     /**
      * Get mock record driver
      *
@@ -68,24 +147,87 @@ class ResultScrollerTest extends TestCase
      */
     protected function getMockRecordDriver($id, $source = 'VuFind')
     {
-        $driver = $this->getMockBuilder('VuFind\RecordDriver\AbstractBase')
-            ->disableOriginalConstructor()
-            ->getMock();
-        $driver->expects($this->any())->method('getUniqueId')->will($this->returnValue($id));
-        $driver->expects($this->any())->method('getResourceSource')->will($this->returnValue($source));
-        return $driver;
+        if (!isset($this->recordDrivers["$source|$id"])) {
+            $driver = $this->getMockBuilder('VuFind\RecordDriver\AbstractBase')
+                ->disableOriginalConstructor()
+                ->getMock();
+            $driver->expects($this->any())->method('getUniqueId')->will($this->returnValue($id));
+            $driver->expects($this->any())->method('getResourceSource')->will($this->returnValue($source));
+            $this->recordDrivers["$source|$id"] = $driver;
+        }
+        return $this->recordDrivers["$source|$id"];
     }
 
     /**
      * Get mock search results
      *
+     * @param int $page  Current page number
+     * @param int $limit Page size
+     * @param int $total Total size of fake result set
+     *
      * @return \VuFind\Search\Base\Results
      */
-    protected function getMockResults()
+    protected function getMockResults($page = 0, $limit = 0, $total = 0)
     {
         $results = $this->getMockBuilder('VuFind\Search\Solr\Results')
             ->disableOriginalConstructor()
             ->getMock();
+        $results->expects($this->any())->method('getSearchId')->will($this->returnValue('dummy-search-id'));
+        $results->expects($this->any())->method('getParams')->will($this->returnValue($this->getMockParams($page, $limit)));
+        $results->expects($this->any())->method('getResultTotal')->will($this->returnValue($total));
+        $results->expects($this->any())->method('getResults')->will($this->returnValue($this->getResultSet($page, $limit, $total)));
         return $results;
     }
+
+    /**
+     * Get mock search params
+     *
+     * @param int $page  Current page number
+     * @param int $limit Page size
+     *
+     * @return \VuFind\Search\Base\Params
+     */
+    protected function getMockParams($page = 0, $limit = 0)
+    {
+        $params = $this->getMockBuilder('VuFind\Search\Solr\Params')
+            ->disableOriginalConstructor()
+            ->getMock();
+        $params->expects($this->any())->method('getPage')->will($this->returnValue($page));
+        $params->expects($this->any())->method('getLimit')->will($this->returnValue($limit));
+        return $params;
+    }
+
+    /**
+     * Get mock result scroller
+     *
+     * @param array $methods Methods to mock
+     *
+     * @return ResultScroller
+     */
+    protected function getMockResultScroller($methods = array('restoreLastSearch', 'rememberSearch'))
+    {
+        return $this->getMock('VuFind\Controller\Plugin\ResultScroller', $methods);
+    }
+
+    /**
+     * Get set of fake record drivers.
+     *
+     * @param int $page  Current page number
+     * @param int $limit Page size
+     * @param int $total Total size of fake result set
+     *
+     * @return array
+     */
+    protected function getResultSet($page, $limit, $total)
+    {
+        $retVal = array();
+        for ($i = 1; $i <= $limit; $i++) {
+            $current = ($page - 1) * $limit + $i;
+            if ($current > $total) {
+                break;
+            }
+            $retVal[] = $this->getMockRecordDriver($current);
+        }
+        return $retVal;
+    }
 }
\ No newline at end of file