diff --git a/tests/grp_pwd_file_test.cpp b/tests/grp_pwd_file_test.cpp
new file mode 100644
index 0000000..79f9a10
--- /dev/null
+++ b/tests/grp_pwd_file_test.cpp
@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) 2018 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 <unistd.h>
+
+#include <gtest/gtest.h>
+
+#include "TemporaryFile.h"
+
+#if defined(__BIONIC__)
+#include "../libc/bionic/grp_pwd_file.cpp"
+
+void FindAndCheckPasswdEntry(PasswdFile* file, const char* name, uid_t uid, gid_t gid,
+                             const char* dir, const char* shell) {
+  passwd_state_t name_passwd_state;
+  ASSERT_TRUE(file->FindByName(name, &name_passwd_state)) << name;
+
+  passwd& name_passwd = name_passwd_state.passwd_;
+  EXPECT_STREQ(name, name_passwd.pw_name);
+  EXPECT_EQ(nullptr, name_passwd.pw_passwd);
+  EXPECT_EQ(uid, name_passwd.pw_uid);
+  EXPECT_EQ(gid, name_passwd.pw_gid);
+  EXPECT_EQ(nullptr, name_passwd.pw_gecos);
+  EXPECT_STREQ(dir, name_passwd.pw_dir);
+  EXPECT_STREQ(shell, name_passwd.pw_shell);
+
+  passwd_state_t id_passwd_state;
+  ASSERT_TRUE(file->FindById(uid, &id_passwd_state)) << uid;
+
+  passwd& id_passwd = id_passwd_state.passwd_;
+  EXPECT_STREQ(name, id_passwd.pw_name);
+  EXPECT_EQ(nullptr, id_passwd.pw_passwd);
+  EXPECT_EQ(uid, id_passwd.pw_uid);
+  EXPECT_EQ(gid, id_passwd.pw_gid);
+  EXPECT_EQ(nullptr, id_passwd.pw_gecos);
+  EXPECT_STREQ(dir, id_passwd.pw_dir);
+  EXPECT_STREQ(shell, id_passwd.pw_shell);
+}
+
+void FindAndCheckGroupEntry(GroupFile* file, const char* name, gid_t gid) {
+  group_state_t name_group_state;
+  ASSERT_TRUE(file->FindByName(name, &name_group_state)) << name;
+
+  group& name_group = name_group_state.group_;
+  EXPECT_STREQ(name, name_group.gr_name);
+  EXPECT_EQ(nullptr, name_group.gr_passwd);
+  EXPECT_EQ(gid, name_group.gr_gid);
+  EXPECT_EQ(name_group.gr_name, name_group.gr_mem[0]);
+  EXPECT_EQ(nullptr, name_group.gr_mem[1]);
+
+  group_state_t id_group_state;
+  ASSERT_TRUE(file->FindById(gid, &id_group_state)) << gid;
+
+  group& id_group = id_group_state.group_;
+  EXPECT_STREQ(name, id_group.gr_name);
+  EXPECT_EQ(nullptr, id_group.gr_passwd);
+  EXPECT_EQ(gid, id_group.gr_gid);
+  EXPECT_EQ(id_group.gr_name, id_group.gr_mem[0]);
+  EXPECT_EQ(nullptr, id_group.gr_mem[1]);
+}
+
+#endif  // __BIONIC__
+
+TEST(grp_pwd_file, passwd_file_one_entry) {
+#if defined(__BIONIC__)
+  TemporaryFile file;
+  ASSERT_NE(-1, file.fd);
+  static const char test_string[] = "name:password:1:2:user_info:dir:shell\n";
+  write(file.fd, test_string, sizeof(test_string) - 1);
+
+  PasswdFile passwd_file(file.filename);
+
+  FindAndCheckPasswdEntry(&passwd_file, "name", 1, 2, "dir", "shell");
+
+  EXPECT_FALSE(passwd_file.FindByName("not_name", nullptr));
+  EXPECT_FALSE(passwd_file.FindById(3, nullptr));
+
+#else   // __BIONIC__
+  GTEST_LOG_(INFO) << "This test does nothing.\n";
+#endif  // __BIONIC__
+}
+
+TEST(grp_pwd_file, group_file_one_entry) {
+#if defined(__BIONIC__)
+  TemporaryFile file;
+  ASSERT_NE(-1, file.fd);
+  static const char test_string[] = "name:password:1:one,two,three\n";
+  write(file.fd, test_string, sizeof(test_string) - 1);
+
+  GroupFile group_file(file.filename);
+
+  FindAndCheckGroupEntry(&group_file, "name", 1);
+
+  EXPECT_FALSE(group_file.FindByName("not_name", nullptr));
+  EXPECT_FALSE(group_file.FindById(3, nullptr));
+
+#else   // __BIONIC__
+  GTEST_LOG_(INFO) << "This test does nothing.\n";
+#endif  // __BIONIC__
+}
+
+TEST(grp_pwd_file, passwd_file_many_entries) {
+#if defined(__BIONIC__)
+  TemporaryFile file;
+  ASSERT_NE(-1, file.fd);
+  static const char test_string[] =
+      "first:x:1:2::dir:shell\n"
+      "abc1::3:4::def:abc\n"
+      "abc2::5:4:abc::abc\n"
+      "abc3::7:4:abc:def:\n"
+      "abc4::9:4:::abc\n"
+      "abc5::11:4:abc:def:abc\n"
+      "middle-ish::13:4::/:/system/bin/sh\n"
+      "abc7::15:4:abc::\n"
+      "abc8::17:4:::\n"
+      "abc9::19:4:abc:def:abc\n"
+      "abc10::21:4:abc:def:abc\n"
+      "abc11::23:4:abc:def:abc\n"
+      "abc12::25:4:abc:def:abc\n"
+      "abc13::27:4:abc:def:abc\n"
+      "last::29:4::last_user_dir:last_user_shell\n";
+
+  write(file.fd, test_string, sizeof(test_string) - 1);
+
+  PasswdFile passwd_file(file.filename);
+
+  FindAndCheckPasswdEntry(&passwd_file, "first", 1, 2, "dir", "shell");
+  FindAndCheckPasswdEntry(&passwd_file, "middle-ish", 13, 4, "/", "/system/bin/sh");
+  FindAndCheckPasswdEntry(&passwd_file, "last", 29, 4, "last_user_dir", "last_user_shell");
+
+  EXPECT_FALSE(passwd_file.FindByName("not_name", nullptr));
+  EXPECT_FALSE(passwd_file.FindById(50, nullptr));
+
+#else   // __BIONIC__
+  GTEST_LOG_(INFO) << "This test does nothing.\n";
+#endif  // __BIONIC__
+}
+
+TEST(grp_pwd_file, group_file_many_entries) {
+#if defined(__BIONIC__)
+  TemporaryFile file;
+  ASSERT_NE(-1, file.fd);
+  static const char test_string[] =
+      "first:password:1:one,two,three\n"
+      "abc:def:2:group1,group2,group3\n"
+      "abc:def:3:\n"
+      "abc:def:4:\n"
+      "abc:def:5:\n"
+      "middle-ish:def_a_password_that_is_over_32_characters_long:6:\n"
+      "abc:def:7:\n"
+      "abc:def:8:\n"
+      "abc:def:20:\n"
+      "abc:def:25:\n"
+      "abc:def:27:\n"
+      "abc:def:52:\n"
+      "last::800:\n";
+
+  write(file.fd, test_string, sizeof(test_string) - 1);
+
+  GroupFile group_file(file.filename);
+
+  FindAndCheckGroupEntry(&group_file, "first", 1);
+  FindAndCheckGroupEntry(&group_file, "middle-ish", 6);
+  FindAndCheckGroupEntry(&group_file, "last", 800);
+
+  EXPECT_FALSE(group_file.FindByName("not_name", nullptr));
+  EXPECT_FALSE(group_file.FindById(799, nullptr));
+
+#else   // __BIONIC__
+  GTEST_LOG_(INFO) << "This test does nothing.\n";
+#endif  // __BIONIC__
+}