Disentangle fpdfsave_embeddertest's FPDF_FILEWRITE, use gmock matchers.

fpdfsdk/src/fpdfsave_embeddertest.cpp

 // 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 <string.h>
 
 #include "core/include/fxcrt/fx_string.h"
 #include "public/fpdf_save.h"
 #include "public/fpdfview.h"
 #include "testing/embedder_test.h"
 #include "testing/fx_string_testhelpers.h"
+#include "testing/gmock/include/gmock/gmock-matchers.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "testing/test_support.h"
 
-class FPDFSaveEmbedderTest : public EmbedderTest, public FPDF_FILEWRITE {
- public:
-  FPDFSaveEmbedderTest() {
-    FPDF_FILEWRITE::version = 1;
-    FPDF_FILEWRITE::WriteBlock = WriteBlockCallback;
-  }
-  bool SaveDocumentToString() {
-    m_String.clear();
-    return FPDF_SaveAsCopy(document(), this, 0);
-  }
-  bool SaveDocumentWithVersionToString(int version) {
-    m_String.clear();
-    return FPDF_SaveWithVersion(document(), this, 0, version);
-  }
-  const std::string& GetString() const { return m_String; }
-
- private:
-  static int WriteBlockCallback(FPDF_FILEWRITE* pFileWrite,
-                                const void* data,
-                                unsigned long size) {
-    FPDFSaveEmbedderTest* pThis =
-        static_cast<FPDFSaveEmbedderTest*>(pFileWrite);
-    pThis->m_String.append(static_cast<const char*>(data), size);
-    return 1;
-  }
-
-  std::string m_String;
-};
+class FPDFSaveEmbedderTest : public EmbedderTest, public TestSaver {};
 
 TEST_F(FPDFSaveEmbedderTest, SaveSimpleDoc) {
   EXPECT_TRUE(OpenDocument("hello_world.pdf"));
-  EXPECT_TRUE(SaveDocumentToString());
-  EXPECT_EQ("%PDF-1.7\r\n", GetString().substr(0, 10));
+  EXPECT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
+  EXPECT_THAT(GetString(), testing::StartsWith("%PDF-1.7\r\n"));
   EXPECT_EQ(843, GetString().length());
 }
 
 TEST_F(FPDFSaveEmbedderTest, SaveSimpleDocWithVersion) {
   EXPECT_TRUE(OpenDocument("hello_world.pdf"));
-  EXPECT_TRUE(SaveDocumentWithVersionToString(14));
-  EXPECT_EQ("%PDF-1.4\r\n", GetString().substr(0, 10));
+  EXPECT_TRUE(FPDF_SaveWithVersion(document(), this, 0, 14));
+  EXPECT_THAT(GetString(), testing::StartsWith("%PDF-1.4\r\n"));
   EXPECT_EQ(843, GetString().length());
 }
 
 TEST_F(FPDFSaveEmbedderTest, SaveSimpleDocWithBadVersion) {
   EXPECT_TRUE(OpenDocument("hello_world.pdf"));
-  EXPECT_TRUE(SaveDocumentWithVersionToString(-1));
-  EXPECT_EQ("%PDF-1.7\r\n", GetString().substr(0, 10));
-  EXPECT_TRUE(SaveDocumentWithVersionToString(0));
-  EXPECT_EQ("%PDF-1.7\r\n", GetString().substr(0, 10));
-  EXPECT_TRUE(SaveDocumentWithVersionToString(18));
-  EXPECT_EQ("%PDF-1.7\r\n", GetString().substr(0, 10));
+  EXPECT_TRUE(FPDF_SaveWithVersion(document(), this, 0, -1));
+  EXPECT_THAT(GetString(), testing::StartsWith("%PDF-1.7\r\n"));
+
+  ClearString();
+  EXPECT_TRUE(FPDF_SaveWithVersion(document(), this, 0, 0));
+  EXPECT_THAT(GetString(), testing::StartsWith("%PDF-1.7\r\n"));
+
+  ClearString();
+  EXPECT_TRUE(FPDF_SaveWithVersion(document(), this, 0, 18));
+  EXPECT_THAT(GetString(), testing::StartsWith("%PDF-1.7\r\n"));
 }
 
 TEST_F(FPDFSaveEmbedderTest, BUG_342) {
   EXPECT_TRUE(OpenDocument("hello_world.pdf"));
-  EXPECT_TRUE(SaveDocumentToString());
-  EXPECT_EQ(std::string::npos, GetString().find("0000000000 65536 f\r\n"));
-  EXPECT_NE(std::string::npos, GetString().find("0000000000 65535 f\r\n"));
+  EXPECT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
+  EXPECT_THAT(GetString(), testing::HasSubstr("0000000000 65535 f\r\n"));
+  EXPECT_THAT(GetString(),
+              testing::Not(testing::HasSubstr("0000000000 65536 f\r\n")));
 }