Add WriteIsolatedOutput() functions

webrtc/test/testsupport/isolated_output_unittest.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/test/testsupport/isolated_output.h"
+
+#include <string.h>
+
+#include <string>
+
+#include "gflags/gflags.h"
+#include "webrtc/base/file.h"
+#include "webrtc/base/pathutils.h"
+#include "webrtc/test/gtest.h"
+
+DECLARE_string(isolated_out_dir);
+
+namespace webrtc {
+namespace test {
+
+TEST(IsolatedOutputTest, ShouldRejectInvalidIsolatedOutDir) {
+  std::string backup = FLAGS_isolated_out_dir;
+  FLAGS_isolated_out_dir = "";
+  ASSERT_FALSE(WriteIsolatedOutput("a-file", "some-contents"));
+  FLAGS_isolated_out_dir = backup;
+}
+
+TEST(IsolatedOutputTest, ShouldRejectInvalidFileName) {
+  ASSERT_FALSE(WriteIsolatedOutput(nullptr, "some-contents"));
+  ASSERT_FALSE(WriteIsolatedOutput("", "some-contents"));
+}
+
+// Sets isolated_out_dir=<a-writable-path> to execute this test.
+TEST(IsolatedOutputTest, ShouldBeAbleToWriteContent) {
+  const char* filename = "a-file";
+  const char* content = "some-contents";
+  if (WriteIsolatedOutput(filename, content)) {
+    rtc::File input =
+        rtc::File::Open(rtc::Pathname(FLAGS_isolated_out_dir, filename));
+    ASSERT_TRUE(input.IsOpen());
+    ASSERT_TRUE(input.Seek(0));
+    uint8_t buffer[32];
+    ASSERT_EQ(input.Read(buffer, strlen(content)), strlen(content));
+    buffer[strlen(content)] = 0;
+    ASSERT_EQ(std::string(content),
+              std::string(reinterpret_cast<char*>(buffer)));
+  }

[kjellander_webrtc, 2016/12/08 11:51:28]

Please add cleaning of the file and ensure it always happens. I think you either
need to change ASSERT->EXPECT or use a gtest fixture class+TEST_F and implement
TearDown().
Our tests shouldn't leave any files around after executing successfully (only on
failures).

[Hzj_jie, 2016/12/08 23:01:09]

Done.

+}
+
+}  // namespace test
+}  // namespace webrtc