[Android] Sort custom search engines based on last visited time and display only top 3 most recentl…

chrome/android/javatests/src/org/chromium/chrome/browser/search_engines/TemplateUrlServiceTest.java

 // Copyright 2013 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.
 
 package org.chromium.chrome.browser.search_engines;
 
 import android.net.Uri;
 import android.test.suitebuilder.annotation.SmallTest;
 
 import org.chromium.base.ThreadUtils;
@@ skipping 137 matching lines @@
         });
         searchEngineKeyword = ThreadUtils.runOnUiThreadBlockingNoException(new Callable<String>() {
             @Override
             public String call() throws Exception {
                 return templateUrlService.getDefaultSearchEngineTemplateUrl().getKeyword();
             }
         });
         assertEquals(searchEngines.get(1).getKeyword(), searchEngineKeyword);
     }
 
+    @SmallTest
+    @Feature({"SearchEngines"})
+    public void testSortandGetCustomSearchEngine() throws InterruptedException {
+        final TemplateUrlService templateUrlService = waitForTemplateUrlServiceToLoad();
+
+        // Add custom search engines and verified only engines visited within 2 days are added.
+        // Also verified custom engines are sorted correctly.
+        List<TemplateUrl> searchEngines =
+                ThreadUtils.runOnUiThreadBlockingNoException(new Callable<List<TemplateUrl>>() {
+                    @Override
+                    public List<TemplateUrl> call() throws Exception {
+                        templateUrlService.addSearchEngineForTesting("keyword1", 0);
+                        templateUrlService.addSearchEngineForTesting("keyword2", 0);
+                        templateUrlService.addSearchEngineForTesting("keyword3", 3);
+                        return templateUrlService.getSearchEngines();
+                    }
+                });
+        assertEquals(7, searchEngines.size());

[Ted C, 2016/12/15 21:38:06]

I assume the 7 comes from the fact that there are 5 prepopulated engines right?

If so, I would get the initial size before adding any new search engines.  Then
I would track the delta (here's you are expecting two new search engines only). 
If not, adding or removing a default search engine (or if your phone is in a
different region), the test might not pass.

Or, maybe it would be better do use this:
https://developer.android.com/reference/java/util/List.html#subList(int, int)
and just return the search engines after the pre-populated ones.

[ltian, 2016/12/15 22:56:54]

Return the sublist after pre-populated ones is a great idea, change to it!

+        assertEquals("keyword2", searchEngines.get(5).getKeyword());
+        assertEquals("keyword1", searchEngines.get(6).getKeyword());
+
+        // Add more custom search engines and verified at most 3 custom engines are returned.
+        // Also verified custom engines are sorted correctly.
+        searchEngines =
+                ThreadUtils.runOnUiThreadBlockingNoException(new Callable<List<TemplateUrl>>() {
+                    @Override
+                    public List<TemplateUrl> call() throws Exception {
+                        templateUrlService.addSearchEngineForTesting("keyword4", 0);
+                        templateUrlService.addSearchEngineForTesting("keyword5", 0);
+                        return templateUrlService.getSearchEngines();
+                    }
+                });
+        assertEquals(8, searchEngines.size());
+        assertEquals("keyword5", searchEngines.get(5).getKeyword());
+        assertEquals("keyword4", searchEngines.get(6).getKeyword());
+        assertEquals("keyword2", searchEngines.get(7).getKeyword());
+
+        // Verified last_visited is updated correctly and sorting in descending order correctly.
+        searchEngines =
+                ThreadUtils.runOnUiThreadBlockingNoException(new Callable<List<TemplateUrl>>() {
+                    @Override
+                    public List<TemplateUrl> call() throws Exception {
+                        templateUrlService.updateLastVisitedForTesting("keyword3");
+                        return templateUrlService.getSearchEngines();
+                    }
+                });
+        assertEquals(8, searchEngines.size());
+        assertEquals("keyword3", searchEngines.get(5).getKeyword());
+        assertEquals("keyword5", searchEngines.get(6).getKeyword());
+        assertEquals("keyword4", searchEngines.get(7).getKeyword());
+
+        // Set a custom engine as default provider and verified still 3 custom engines are returned.
+        // Also verified custom engines are sorted correctly.
+        searchEngines =
+                ThreadUtils.runOnUiThreadBlockingNoException(new Callable<List<TemplateUrl>>() {
+                    @Override
+                    public List<TemplateUrl> call() throws Exception {
+                        templateUrlService.setSearchEngine("keyword4");
+                        return templateUrlService.getSearchEngines();
+                    }
+                });
+        assertEquals(9, searchEngines.size());
+        assertEquals("keyword4", searchEngines.get(5).getKeyword());
+        assertEquals("keyword3", searchEngines.get(6).getKeyword());
+        assertEquals("keyword5", searchEngines.get(7).getKeyword());
+        assertEquals("keyword2", searchEngines.get(8).getKeyword());
+    }
+
     private TemplateUrlService waitForTemplateUrlServiceToLoad() throws InterruptedException {
         final AtomicBoolean observerNotified = new AtomicBoolean(false);
         final LoadListener listener = new LoadListener() {
             @Override
             public void onTemplateUrlServiceLoaded() {
                 observerNotified.set(true);
             }
         };
         final TemplateUrlService templateUrlService = ThreadUtils.runOnUiThreadBlockingNoException(
                 new Callable<TemplateUrlService>() {
                     @Override
                     public TemplateUrlService call() {
                         TemplateUrlService service = TemplateUrlService.getInstance();
                         service.registerLoadListener(listener);
                         service.load();
                         return service;
                     }
                 });
 
         CriteriaHelper.pollInstrumentationThread(new Criteria(
                 "Observer wasn't notified of TemplateUrlService load.") {
             @Override
             public boolean isSatisfied() {
                 return observerNotified.get();
             }
         });
         return templateUrlService;
     }
 }