Introducing JSBigFileString

Reviewed By: michalgr

Differential Revision: D4189896

fbshipit-source-id: 0f3cebcd7e76d5c763c29ebc1119ae24b643e5ad

ReactCommon/cxxreact/tests/jsbigstring.cpp

@@ -0,0 +1,61 @@
+
+// Copyright 2004-present Facebook. All Rights Reserved.
+#include <sys/mman.h>
+#include <fcntl.h>
+
+#include <folly/File.h>
+#include <gtest/gtest.h>
+#include <cxxreact/Executor.h>
+#include <cxxreact/MessageQueueThread.h>
+#include <cxxreact/MethodCall.h>
+
+using namespace facebook;
+using namespace facebook::react;
+
+namespace {
+int tempFileFromString(std::string contents)
+{
+  std::string tmp {getenv("TMPDIR")};
+  tmp += "/temp.XXXXX";
+
+  std::vector<char> tmpBuf {tmp.begin(), tmp.end()};
+  tmpBuf.push_back('\0');
+
+  const int fd = mkstemp(tmpBuf.data());
+  write(fd, contents.c_str(), contents.size() + 1);
+
+  return fd;
+}
+};
+
+TEST(JSBigFileString, MapWholeFileTest) {
+  std::string data {"Hello, world"};
+  const auto size = data.length() + 1;
+
+  // Initialise Big String
+  int fd = tempFileFromString("Hello, world");
+  JSBigFileString bigStr {fd, size};
+
+  // Test
+  ASSERT_EQ(fd, bigStr.fd());
+  ASSERT_STREQ(data.c_str(), bigStr.c_str());
+}
+
+TEST(JSBigFileString, MapPartTest) {
+  std::string data {"Hello, world"};
+
+  // Sub-string to actually map
+  std::string needle {"or"};
+  off_t offset = data.find(needle);
+
+  // Initialise Big String
+  int fd = tempFileFromString(data);
+  JSBigFileString bigStr {fd, needle.size(), offset};
+
+  // Test
+  ASSERT_EQ(fd, bigStr.fd());
+  ASSERT_EQ(needle.length(), bigStr.size());
+  for (unsigned int i = 0; i < needle.length(); ++i) {
+    ASSERT_EQ(needle[i], bigStr.c_str()[i]);
+  }
+}