In order to land https://codereview.webrtc.org/2790933002/ and due to the

ongoing clean-up work (see https://codereview.webrtc.org/2887093002,
https://codereview.webrtc.org/2894583002/ and
https://codereview.webrtc.org/2891923002/), ReadDirectory() has been
added in webrtc/test/testsupport/fileutils.h.

BUG=NOBUG

Review-Url: https://codereview.webrtc.org/2898753002
Cr-Commit-Position: refs/heads/master@{#18369}

webrtc/test/testsupport/fileutils.cc

@@ -24,6 +24,7 @@
 #include "webrtc/base/win32.h"
 #define GET_CURRENT_DIR _getcwd
 #else
+#include <dirent.h>
 #include <unistd.h>
 
 #define GET_CURRENT_DIR getcwd
@@ -39,7 +40,9 @@
 #include <string.h>
 
 #include <memory>
+#include <utility>
 
+#include "webrtc/base/checks.h"
 #include "webrtc/typedefs.h"  // For architecture defines
 
 namespace webrtc {
@@ -126,7 +129,7 @@ std::string WorkingDir() {
   return kRootDirName;
 }
 
-#else // WEBRTC_ANDROID
+#else  // WEBRTC_ANDROID
 
 std::string ProjectRootPath() {
 #if defined(WEBRTC_IOS)
@@ -212,6 +215,57 @@ std::string TempFilename(const std::string &dir, const std::string &prefix) {
 #endif
 }
 
+rtc::Optional<std::vector<std::string>> ReadDirectory(std::string path) {
+  if (path.length() == 0)
+    return rtc::Optional<std::vector<std::string>>();
+
+#if defined(WEBRTC_WIN)
+  // Append separator character if needed.
+  if (path.back() != '\\')
+    path += '\\';
+
+  // Init.
+  WIN32_FIND_DATA data;
+  HANDLE handle = ::FindFirstFile(rtc::ToUtf16(path + '*').c_str(), &data);
+  if (handle == INVALID_HANDLE_VALUE)
+    return rtc::Optional<std::vector<std::string>>();
+
+  // Populate output.
+  std::vector<std::string> found_entries;
+  do {
+    const std::string name = rtc::ToUtf8(data.cFileName);
+    if (name != "." && name != "..")
+      found_entries.emplace_back(path + name);
+  } while (::FindNextFile(handle, &data) == TRUE);
+
+  // Release resources.
+  if (handle != INVALID_HANDLE_VALUE)
+    ::FindClose(handle);
+#else
+  // Append separator character if needed.
+  if (path.back() != '/')
+    path += '/';
+
+  // Init.
+  DIR* dir = ::opendir(path.c_str());
+  if (dir == nullptr)
+    return rtc::Optional<std::vector<std::string>>();
+
+  // Populate output.
+  std::vector<std::string> found_entries;
+  while (dirent* dirent = readdir(dir)) {
+    const std::string& name = dirent->d_name;
+    if (name != "." && name != "..")
+      found_entries.emplace_back(path + name);
+  }
+
+  // Release resources.
+  closedir(dir);
+#endif
+
+  return rtc::Optional<std::vector<std::string>>(std::move(found_entries));
+}
+
 bool CreateDir(const std::string& directory_name) {
   struct stat path_info = {0};
   // Check if the path exists already:

webrtc/test/testsupport/fileutils.h

@@ -14,6 +14,9 @@
 #define WEBRTC_TEST_TESTSUPPORT_FILEUTILS_H_
 
 #include <string>
+#include <vector>
+
+#include "webrtc/base/optional.h"
 
 namespace webrtc {
 namespace test {
@@ -66,6 +69,12 @@ std::string ResourcePath(const std::string& name,
 // directory.
 std::string WorkingDir();
 
+// Reads the content of a directory and, in case of success, returns a vector
+// of strings with one element for each found file or directory. Each element is
+// a path created by prepending |dir| to the file/directory name. "." and ".."
+// are never added in the returned vector.
+rtc::Optional<std::vector<std::string>> ReadDirectory(std::string path);
+
 // Creates a directory if it not already exists.
 // Returns true if successful. Will print an error message to stderr and return
 // false if a file with the same name already exists.

webrtc/test/testsupport/fileutils_unittest.cc

@@ -12,9 +12,14 @@
 
 #include <stdio.h>
 
+#include <fstream>
+#include <iostream>
 #include <list>
 #include <string>
 
+#include "webrtc/base/checks.h"
+#include "webrtc/base/optional.h"
+#include "webrtc/base/pathutils.h"
 #include "webrtc/test/gtest.h"
 
 #ifdef WIN32
@@ -24,11 +29,41 @@ static const char* kPathDelimiter = "\\";
 static const char* kPathDelimiter = "/";
 #endif
 
-static const std::string kResourcesDir = "resources";
-static const std::string kTestName = "fileutils_unittest";
-static const std::string kExtension = "tmp";
+static const char kTestName[] = "fileutils_unittest";
+static const char kExtension[] = "tmp";
 
 namespace webrtc {
+namespace test {
+
+namespace {
+
+// Remove files and directories in a directory non-recursively and writes the
+// number of deleted items in |num_deleted_entries|.
+void CleanDir(const std::string& dir, size_t* num_deleted_entries) {
+  RTC_DCHECK(num_deleted_entries);
+  *num_deleted_entries = 0;
+  rtc::Optional<std::vector<std::string>> dir_content = ReadDirectory(dir);
+  EXPECT_TRUE(dir_content);
+  for (const auto& entry : *dir_content) {
+    if (DirExists(entry)) {
+      EXPECT_TRUE(RemoveDir(entry));
+      (*num_deleted_entries)++;
+    } else if (FileExists(entry)) {
+      EXPECT_TRUE(RemoveFile(entry));
+      (*num_deleted_entries)++;
+    } else {
+      FAIL();
+    }
+  }
+}
+
+void WriteStringInFile(const std::string& what, const std::string& file_path) {
+  std::ofstream out(file_path);
+  out << what;
+  out.close();
+}
+
+}  // namespace
 
 // Test fixture to restore the working directory between each test, since some
 // of them change it with chdir during execution (not restored by the
@@ -170,4 +205,36 @@ TEST_F(FileUtilsTest, DirExists) {
   remove(temp_filename.c_str());
 }
 
+TEST_F(FileUtilsTest, WriteReadDeleteFilesAndDirs) {
+  size_t num_deleted_entries;
+
+  // Create an empty temporary directory for this test.
+  const std::string temp_directory =
+      OutputPath() + "TempFileUtilsTestReadDirectory" + kPathDelimiter;
+  CreateDir(temp_directory);
+  EXPECT_NO_FATAL_FAILURE(CleanDir(temp_directory, &num_deleted_entries));
+  EXPECT_TRUE(DirExists(temp_directory));
+
+  // Add a file.
+  const std::string temp_filename = temp_directory + "TempFilenameTest";
+  WriteStringInFile("test\n", temp_filename);
+  EXPECT_TRUE(FileExists(temp_filename));
+
+  // Add an empty directory.
+  const std::string temp_subdir = temp_directory + "subdir" + kPathDelimiter;
+  EXPECT_TRUE(CreateDir(temp_subdir));
+  EXPECT_TRUE(DirExists(temp_subdir));
+
+  // Checks.
+  rtc::Optional<std::vector<std::string>> dir_content =
+      ReadDirectory(temp_directory);
+  EXPECT_TRUE(dir_content);
+  EXPECT_EQ(2u, dir_content->size());
+  EXPECT_NO_FATAL_FAILURE(CleanDir(temp_directory, &num_deleted_entries));
+  EXPECT_EQ(2u, num_deleted_entries);
+  EXPECT_TRUE(RemoveDir(temp_directory));
+  EXPECT_FALSE(DirExists(temp_directory));
+}
+
+}  // namespace test
 }  // namespace webrtc