Support for distilling prior pages in an article.

components/dom_distiller/core/distiller_unittest.cc

Index: components/dom_distiller/core/distiller_unittest.cc
diff --git a/components/dom_distiller/core/distiller_unittest.cc b/components/dom_distiller/core/distiller_unittest.cc
index 16b8d23a31d34bb1f8404dc681bdb7b730e96c71..6301f74f6b737a4b41bedf8068fe9ce653369d66 100644
--- a/components/dom_distiller/core/distiller_unittest.cc
+++ b/components/dom_distiller/core/distiller_unittest.cc
@@ -46,12 +46,14 @@ const size_t kMaxPagesInArticle = 10;
       const string& title,
       const string& content,
       const vector<int>& image_indices,
-      const string& next_page_url) {
+      const string& next_page_url,
+      const string& prev_page_url = "") {
     scoped_ptr<base::ListValue> list(new base::ListValue());
 
     list->AppendString(title);
     list->AppendString(content);
     list->AppendString(next_page_url);
+    list->AppendString(prev_page_url);
     for (size_t i = 0; i < image_indices.size(); ++i) {
       list->AppendString(kImageURLs[image_indices[i]]);
     }
@@ -149,14 +151,22 @@ ACTION_P2(CreateMockDistillerPage, list, kurl) {
   return distiller_page;
 }
 
-ACTION_P3(CreateMockDistillerPages, lists, kurls, num_pages) {
+ACTION_P4(CreateMockDistillerPages, lists, kurls, num_pages, start_page_num) {
   DistillerPage::Delegate* delegate = arg0;
   MockDistillerPage* distiller_page = new MockDistillerPage(delegate);
   EXPECT_CALL(*distiller_page, InitImpl());
   {
     testing::InSequence s;
-
-    for (int page = 0; page < num_pages; ++page) {
+    // Distiller prefers distilling past pages first. E.g. when distillation
+    // starts on page 2 then pages are distilled in the order: 2, 1, 0, 3, 4.
+    vector<int> page_nums;
+    for (int page = start_page_num; page >= 0; --page)
+      page_nums.push_back(page);
+    for (int page = start_page_num + 1; page < num_pages; ++page)
+      page_nums.push_back(page);
+
+    for (size_t page_num = 0; page_num < page_nums.size(); ++page_num) {
+      int page = page_nums[page_num];
       GURL url = GURL(kurls[page]);
       EXPECT_CALL(*distiller_page, LoadURLImpl(url))
           .WillOnce(testing::InvokeWithoutArgs(distiller_page,
@@ -247,7 +257,7 @@ TEST_F(DistillerTest, DistillMultiplePages) {
   }
 
   EXPECT_CALL(page_factory_, CreateDistillerPageMock(_))
-      .WillOnce(CreateMockDistillerPages(list, page_urls, kNumPages));
+      .WillOnce(CreateMockDistillerPages(list, page_urls, kNumPages, 0));
 
   distiller_.reset(new DistillerImpl(page_factory_, url_fetcher_factory_));
   distiller_->Init();
@@ -310,7 +320,7 @@ TEST_F(DistillerTest, CheckMaxPageLimit) {
 
   EXPECT_CALL(page_factory_, CreateDistillerPageMock(_))
       .WillOnce(CreateMockDistillerPages(
-          list, page_urls, static_cast<int>(kMaxPagesInArticle)));
+          list, page_urls, static_cast<int>(kMaxPagesInArticle), 0));
 
   distiller_.reset(new DistillerImpl(page_factory_, url_fetcher_factory_));
 
@@ -366,7 +376,7 @@ TEST_F(DistillerTest, MultiplePagesDistillationFailure) {
   // Expect only calls till the failed page number.
   EXPECT_CALL(page_factory_, CreateDistillerPageMock(_))
       .WillOnce(CreateMockDistillerPages(
-          distilled_values, page_urls, failed_page_num + 1));
+          distilled_values, page_urls, failed_page_num + 1, 0));
 
   distiller_.reset(new DistillerImpl(page_factory_, url_fetcher_factory_));
   distiller_->Init();
@@ -383,4 +393,44 @@ TEST_F(DistillerTest, MultiplePagesDistillationFailure) {
   }
 }
 
+TEST_F(DistillerTest, DistillPreviousPage) {
+  base::MessageLoopForUI loop;
+  const int kNumPages = 8;
+  string content[kNumPages];
+  string page_urls[kNumPages];
+  scoped_ptr<base::Value> distilled_values[kNumPages];
+
+  // The page number of the article on which distillation starts.
+  int start_page_number = 3;
+  string url_prefix = "http://a.com/";
+  for (int page_no = 0; page_no < kNumPages; ++page_no) {
+    page_urls[page_no] = url_prefix + base::IntToString(page_no);
+    content[page_no] = "Content for page:" + base::IntToString(page_no);
+    string next_page_url = (page_no + 1 < kNumPages)
+                               ? url_prefix + base::IntToString(page_no + 1)
+                               : "";
+    string prev_page_url = (page_no > 0) ? page_urls[page_no - 1] : "";
+    distilled_values[page_no] = CreateDistilledValueReturnedFromJS(
+        kTitle, content[page_no], vector<int>(), next_page_url, prev_page_url);
+  }
+
+  EXPECT_CALL(page_factory_, CreateDistillerPageMock(_))
+      .WillOnce(CreateMockDistillerPages(
+          distilled_values, page_urls, kNumPages, start_page_number));
+
+  distiller_.reset(new DistillerImpl(page_factory_, url_fetcher_factory_));
+  distiller_->Init();
+  distiller_->DistillPage(
+      GURL(page_urls[start_page_number]),
+      base::Bind(&DistillerTest::OnDistillPageDone, base::Unretained(this)));
+  base::MessageLoop::current()->RunUntilIdle();
+  EXPECT_EQ(kTitle, article_proto_->title());
+  EXPECT_EQ(kNumPages, article_proto_->pages_size());
+  for (int page_no = 0; page_no < kNumPages; ++page_no) {
+    const DistilledPageProto& page = article_proto_->pages(page_no);
+    EXPECT_EQ(content[page_no], page.html());
+    EXPECT_EQ(page_urls[page_no], page.url());
+  }
+}
+
 }  // namespace dom_distiller