diff --git a/tests/stdio_ext_test.cpp b/tests/stdio_ext_test.cpp
new file mode 100644
index 0000000..3dbc485
--- /dev/null
+++ b/tests/stdio_ext_test.cpp
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio_ext.h>
+
+#include <gtest/gtest.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <math.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <wchar.h>
+#include <locale.h>
+
+#include "TemporaryFile.h"
+
+TEST(stdio_ext, __fbufsize) {
+  FILE* fp = fopen("/proc/version", "r");
+
+  char buf[128];
+
+  ASSERT_EQ(0, setvbuf(fp, buf, _IOFBF, 1));
+  ASSERT_EQ(1U, __fbufsize(fp));
+
+  ASSERT_EQ(0, setvbuf(fp, buf, _IOFBF, 8));
+  ASSERT_EQ(8U, __fbufsize(fp));
+
+  fclose(fp);
+}
+
+TEST(stdio_ext, __flbf) {
+  FILE* fp = fopen("/proc/version", "r");
+
+  ASSERT_FALSE(__flbf(fp));
+
+  char buf[128];
+  ASSERT_EQ(0, setvbuf(fp, buf, _IOLBF, sizeof(buf)));
+
+  ASSERT_TRUE(__flbf(fp));
+
+  fclose(fp);
+}
+
+TEST(stdio_ext, __fpending) {
+  FILE* fp = fopen("/dev/null", "w");
+  ASSERT_EQ(0U, __fpending(fp));
+  ASSERT_EQ('x', fputc('x', fp));
+  ASSERT_EQ(1U, __fpending(fp));
+  ASSERT_EQ('y', fputc('y', fp));
+  ASSERT_EQ(2U, __fpending(fp));
+  fflush(fp);
+  ASSERT_EQ(0U, __fpending(fp));
+  fclose(fp);
+}
+
+TEST(stdio_ext, __fpurge) {
+  FILE* fp = tmpfile();
+
+  ASSERT_EQ('a', fputc('a', fp));
+  ASSERT_EQ(1U, __fpending(fp));
+  __fpurge(fp);
+  ASSERT_EQ(0U, __fpending(fp));
+
+  ASSERT_EQ('b', fputc('b', fp));
+  ASSERT_EQ('\n', fputc('\n', fp));
+  ASSERT_EQ(2U, __fpending(fp));
+
+  rewind(fp);
+
+  char buf[16];
+  char* s = fgets(buf, sizeof(buf), fp);
+  ASSERT_TRUE(s != NULL);
+  ASSERT_STREQ("b\n", s);
+
+  fclose(fp);
+}
+
+TEST(stdio_ext, _flushlbf) {
+  FILE* fp = fopen("/dev/null", "w");
+
+  char buf[128];
+  ASSERT_EQ(0, setvbuf(fp, buf, _IOLBF, sizeof(buf)));
+
+  ASSERT_EQ('a', fputc('a', fp));
+  ASSERT_EQ(1U, __fpending(fp));
+
+  _flushlbf();
+
+  ASSERT_EQ(0U, __fpending(fp));
+
+  fclose(fp);
+}
+
+TEST(stdio_ext, __freadable__fwritable) {
+  FILE* fp = fopen("/dev/null", "r");
+  ASSERT_TRUE(__freadable(fp));
+  ASSERT_FALSE(__fwritable(fp));
+  fclose(fp);
+
+  fp = fopen("/dev/null", "w");
+  ASSERT_FALSE(__freadable(fp));
+  ASSERT_TRUE(__fwritable(fp));
+  fclose(fp);
+
+  fp = fopen("/dev/null", "w+");
+  ASSERT_TRUE(__freadable(fp));
+  ASSERT_TRUE(__fwritable(fp));
+  fclose(fp);
+}
+
+TEST(stdio_ext, __fsetlocking) {
+  FILE* fp = fopen("/proc/version", "r");
+  // Android doesn't actually support the other modes.
+  ASSERT_EQ(FSETLOCKING_INTERNAL, __fsetlocking(fp, FSETLOCKING_QUERY));
+  fclose(fp);
+}