diff --git a/test/gtest-extra-test.cc b/test/gtest-extra-test.cc
index 5b79bbb3..02feaa01 100644
--- a/test/gtest-extra-test.cc
+++ b/test/gtest-extra-test.cc
@@ -204,7 +204,7 @@ TEST(FileTest, MoveAssignmentClosesFile) {
   File f2("CMakeLists.txt", File::RDONLY);
   int old_fd = f2.descriptor();
   f2 = std::move(f);
-  EXPECT_CLOSED(old_fd);
+  EXPECT_TRUE(IsClosedInternal(old_fd));
 }
 
 File OpenFile(int &fd) {
@@ -272,7 +272,7 @@ TEST(FileTest, CloseError) {
   EXPECT_EQ(message, error.what());
 }
 
-// Attempts to read count characters from the file.
+// Attempts to read count characters from a file.
 std::string Read(File &f, std::size_t count) {
   std::string buffer(count, '\0');
   std::streamsize offset = 0, n = 0;
@@ -284,6 +284,17 @@ std::string Read(File &f, std::size_t count) {
   return buffer;
 }
 
+// Attempts to write a string to a file.
+void Write(File &f, fmt::StringRef s) {
+  std::size_t num_chars_left = s.size();
+  const char *ptr = s.c_str();
+  do {
+    std::streamsize count = f.write(ptr, num_chars_left);
+    ptr += count;
+    num_chars_left -= count;
+  } while (num_chars_left != 0);
+}
+
 #define EXPECT_READ(file, expected_content) \
   EXPECT_EQ(expected_content, Read(file, std::strlen(expected_content)))
 
@@ -299,17 +310,11 @@ TEST(FileTest, ReadError) {
 }
 
 TEST(FileTest, Write) {
-  const char MESSAGE[] = "test";
   File read_end, write_end;
   File::pipe(read_end, write_end);
-  enum { SIZE = sizeof(MESSAGE) - 1 };
-  std::streamsize offset = 0, count = 0;
-  do {
-    count = write_end.write(MESSAGE + offset, SIZE - offset);
-    offset += count;
-  } while (offset < SIZE && count != 0);
-  write_end = File();  // Close file.
-  EXPECT_READ(read_end, MESSAGE);
+  Write(write_end, "test");
+  write_end.close();
+  EXPECT_READ(read_end, "test");
 }
 
 TEST(FileTest, WriteError) {
@@ -341,7 +346,7 @@ TEST(FileTest, Dup2) {
 TEST(FileTest, Dup2Error) {
   File f(".travis.yml", File::RDONLY);
   EXPECT_SYSTEM_ERROR(f.dup2(-1), EBADF,
-      fmt::Format("cannot duplicate file descriptor {} to -1") << f.descriptor());
+    fmt::Format("cannot duplicate file descriptor {} to -1") << f.descriptor());
 }
 
 TEST(FileTest, Dup2NoExcept) {
@@ -366,7 +371,8 @@ TEST(FileTest, Pipe) {
   File::pipe(read_end, write_end);
   EXPECT_NE(-1, read_end.descriptor());
   EXPECT_NE(-1, write_end.descriptor());
-  // TODO: try writing to write_end and reading from read_end
+  Write(write_end, "test");
+  EXPECT_READ(read_end, "test");
 }
 
 // TODO: test pipe
diff --git a/test/gtest-extra.cc b/test/gtest-extra.cc
index e6db5688..bc9003b7 100644
--- a/test/gtest-extra.cc
+++ b/test/gtest-extra.cc
@@ -82,7 +82,7 @@ void File::close() {
 
 std::streamsize File::read(void *buffer, std::size_t count) {
   std::streamsize result = 0;
-  FMT_RETRY(result, ::read(fd_, buffer, count));
+  FMT_RETRY(result, ::FMT_POSIX(read(fd_, buffer, count)));
   if (result == -1)
     fmt::ThrowSystemError(errno, "cannot read from file");
   return result;
@@ -90,7 +90,7 @@ std::streamsize File::read(void *buffer, std::size_t count) {
 
 std::streamsize File::write(const void *buffer, std::size_t count) {
   std::streamsize result = 0;
-  FMT_RETRY(result, ::write(fd_, buffer, count));
+  FMT_RETRY(result, ::FMT_POSIX(write(fd_, buffer, count)));
   if (result == -1)
     fmt::ThrowSystemError(errno, "cannot write to file");
   return result;
@@ -145,7 +145,7 @@ void File::pipe(File &read_end, File &write_end) {
 OutputRedirector::OutputRedirector(FILE *file) : file_(file) {
   if (std::fflush(file) != 0)
     fmt::ThrowSystemError(errno, "cannot flush stream");
-  int fd = fileno(file);
+  int fd = FMT_POSIX(fileno(file));
   saved_ = File::dup(fd);
   File write_end;
   File::pipe(read_end_, write_end);
@@ -156,7 +156,7 @@ OutputRedirector::~OutputRedirector() {
   if (std::fflush(file_) != 0)
     fmt::ReportSystemError(errno, "cannot flush stream");
   ErrorCode ec;
-  saved_.dup2(fileno(file_), ec);
+  saved_.dup2(FMT_POSIX(fileno(file_)), ec);
   if (ec.get())
     fmt::ReportSystemError(errno, "cannot restore output");
 }