Add CPDF_Document::GetPage() unittests

Added a nontrivial page tree and a test that pages are being fetched
properly, both when requested in order and in reverse order. This will
help prevent introducing bugs while changing the way the page tree is
processed.

BUG=chromium:638513

Review-Url: https://chromiumcodereview.appspot.com/2435783006

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
index caeb029..05408e0 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1634,6 +1634,7 @@
     "core/fpdfapi/page/fpdf_page_parser_old_unittest.cpp",
     "core/fpdfapi/page/fpdf_page_parser_unittest.cpp",
     "core/fpdfapi/parser/cpdf_array_unittest.cpp",
+    "core/fpdfapi/parser/cpdf_document_unittest.cpp",
     "core/fpdfapi/parser/cpdf_object_unittest.cpp",
     "core/fpdfapi/parser/cpdf_parser_unittest.cpp",
     "core/fpdfapi/parser/cpdf_simple_parser_unittest.cpp",

core/fpdfapi/parser/cpdf_document.h

diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index c557a56..ea7bd32 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -102,9 +102,7 @@
                             FX_BOOL bTranslateName = FALSE);
 #endif
 
- private:
-  friend class CPDF_TestDocument;
-
+ protected:
   // Retrieve page count information by getting count value from the tree nodes
   int RetrievePageCount() const;
   CPDF_Dictionary* FindPDFPage(CPDF_Dictionary* pPages,

core/fpdfapi/parser/cpdf_document_unittest.cpp

diff --git a/core/fpdfapi/parser/cpdf_document_unittest.cpp b/core/fpdfapi/parser/cpdf_document_unittest.cpp
new file mode 100644
index 0000000..34661b1
--- /dev/null
+++ b/core/fpdfapi/parser/cpdf_document_unittest.cpp
@@ -0,0 +1,102 @@
+// Copyright 2016 PDFium 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 "core/fpdfapi/parser/cpdf_document.h"
+
+#include <memory>
+
+#include "core/fpdfapi/cpdf_modulemgr.h"
+#include "core/fpdfapi/parser/cpdf_array.h"
+#include "core/fpdfapi/parser/cpdf_dictionary.h"
+#include "core/fpdfapi/parser/cpdf_parser.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+CPDF_Dictionary* CreatePageTreeNode(CPDF_Array* kids,
+                                    CPDF_Document* pDoc,
+                                    int count) {
+  CPDF_Dictionary* pageNode = new CPDF_Dictionary();
+  pageNode->SetStringFor("Type", "Pages");
+  pageNode->SetReferenceFor("Kids", pDoc, pDoc->AddIndirectObject(kids));
+  pageNode->SetIntegerFor("Count", count);
+  uint32_t pageNodeRef = pDoc->AddIndirectObject(pageNode);
+  for (size_t i = 0; i < kids->GetCount(); i++)
+    kids->GetDictAt(i)->SetReferenceFor("Parent", pDoc, pageNodeRef);
+  return pageNode;
+}
+
+CPDF_Dictionary* CreateNumberedPage(size_t number) {
+  CPDF_Dictionary* page = new CPDF_Dictionary();
+  page->SetStringFor("Type", "Page");
+  page->SetIntegerFor("PageNumbering", number);
+  return page;
+}
+
+}  // namespace
+
+class CPDF_TestDocumentForPages : public CPDF_Document {
+ public:
+  CPDF_TestDocumentForPages() : CPDF_Document(nullptr) {
+    CPDF_ModuleMgr* module_mgr = CPDF_ModuleMgr::Get();
+    module_mgr->InitPageModule();
+    // Set up test
+    CPDF_Array* zeroToTwo = new CPDF_Array();
+    zeroToTwo->AddReference(this, AddIndirectObject(CreateNumberedPage(0)));
+    zeroToTwo->AddReference(this, AddIndirectObject(CreateNumberedPage(1)));
+    zeroToTwo->AddReference(this, AddIndirectObject(CreateNumberedPage(2)));
+    CPDF_Dictionary* branch1 = CreatePageTreeNode(zeroToTwo, this, 3);
+
+    CPDF_Array* zeroToThree = new CPDF_Array();
+    zeroToThree->AddReference(this, branch1->GetObjNum());
+    zeroToThree->AddReference(this, AddIndirectObject(CreateNumberedPage(3)));
+    CPDF_Dictionary* branch2 = CreatePageTreeNode(zeroToThree, this, 4);
+
+    CPDF_Array* fourFive = new CPDF_Array();
+    fourFive->AddReference(this, AddIndirectObject(CreateNumberedPage(4)));
+    fourFive->AddReference(this, AddIndirectObject(CreateNumberedPage(5)));
+    CPDF_Dictionary* branch3 = CreatePageTreeNode(fourFive, this, 2);
+
+    CPDF_Array* justSix = new CPDF_Array();
+    justSix->AddReference(this, AddIndirectObject(CreateNumberedPage(6)));
+    CPDF_Dictionary* branch4 = CreatePageTreeNode(justSix, this, 1);
+
+    CPDF_Array* allPages = new CPDF_Array();
+    allPages->AddReference(this, branch2->GetObjNum());
+    allPages->AddReference(this, branch3->GetObjNum());
+    allPages->AddReference(this, branch4->GetObjNum());
+    CPDF_Dictionary* pagesDict = CreatePageTreeNode(allPages, this, 7);
+
+    CPDF_Dictionary* root = new CPDF_Dictionary();
+    root->SetReferenceFor("Pages", this, AddIndirectObject(pagesDict));
+    m_pRootDict = root;
+    m_PageList.SetSize(7);
+  }
+};
+
+TEST(cpdf_document, GetPages) {
+  std::unique_ptr<CPDF_TestDocumentForPages> document =
+      pdfium::MakeUnique<CPDF_TestDocumentForPages>();
+  for (int i = 0; i < 7; i++) {
+    CPDF_Dictionary* page = document->GetPage(i);
+    ASSERT_TRUE(page);
+    ASSERT_TRUE(page->GetObjectFor("PageNumbering"));
+    EXPECT_EQ(i, page->GetIntegerFor("PageNumbering"));
+  }
+  CPDF_Dictionary* page = document->GetPage(7);
+  EXPECT_FALSE(page);
+}
+
+TEST(cpdf_document, GetPagesReverseOrder) {
+  std::unique_ptr<CPDF_TestDocumentForPages> document =
+      pdfium::MakeUnique<CPDF_TestDocumentForPages>();
+  for (int i = 6; i >= 0; i--) {
+    CPDF_Dictionary* page = document->GetPage(i);
+    ASSERT_TRUE(page);
+    ASSERT_TRUE(page->GetObjectFor("PageNumbering"));
+    EXPECT_EQ(i, page->GetIntegerFor("PageNumbering"));
+  }
+  CPDF_Dictionary* page = document->GetPage(7);
+  EXPECT_FALSE(page);
+}