Add tests for Android-specific stubs

Also fix problem with multi-user IDs that the home directory was
returned as "/data" instead of "/" unlike all the other uids.

Change-Id: I914d22052e5a86552989f8969b85aadbc748c65d
diff --git a/tests/stubs_test.cpp b/tests/stubs_test.cpp
new file mode 100644
index 0000000..079779e
--- /dev/null
+++ b/tests/stubs_test.cpp
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2012 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 <gtest/gtest.h>
+
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <pwd.h>
+#include <errno.h>
+#include <limits.h>
+#include <unistd.h>
+
+#if __BIONIC__
+
+#define CHECK_GETPWNAM_FOR(username, uid, uid_type) \
+    SCOPED_TRACE(username); \
+    ASSERT_NO_FATAL_FAILURE(check_getpwnam(username, uid, uid_type));
+
+typedef enum {
+  TYPE_SYSTEM,
+  TYPE_APP
+} uid_type_t;
+
+static void check_getpwnam(const char* username, int uid, uid_type_t uid_type) {
+  errno = 0;
+  passwd* pwd = getpwuid(uid);
+  ASSERT_TRUE(pwd != NULL);
+  ASSERT_EQ(errno, 0);
+  EXPECT_STREQ(username, pwd->pw_name);
+  EXPECT_EQ(uid, pwd->pw_uid);
+  EXPECT_EQ(uid, pwd->pw_gid);
+
+  if (uid_type == TYPE_SYSTEM) {
+    EXPECT_STREQ("/", pwd->pw_dir);
+  } else if (uid_type == TYPE_APP) {
+    EXPECT_STREQ("/data", pwd->pw_dir);
+  }
+
+  EXPECT_STREQ("/system/bin/sh", pwd->pw_shell);
+}
+
+TEST(getpwnam, system_id_root) {
+  CHECK_GETPWNAM_FOR("root", 0, TYPE_SYSTEM);
+}
+
+TEST(getpwnam, system_id_system) {
+  CHECK_GETPWNAM_FOR("system", 1000, TYPE_SYSTEM);
+}
+
+TEST(getpwnam, app_id_radio) {
+  CHECK_GETPWNAM_FOR("radio", 1001, TYPE_SYSTEM);
+}
+
+TEST(getpwnam, app_id_nobody) {
+  CHECK_GETPWNAM_FOR("nobody", 9999, TYPE_SYSTEM);
+}
+
+TEST(getpwnam, app_id_u0_a0) {
+  CHECK_GETPWNAM_FOR("u0_a0", 10000, TYPE_APP);
+}
+
+TEST(getpwnam, app_id_u0_a1234) {
+  CHECK_GETPWNAM_FOR("u0_a1234", 11234, TYPE_APP);
+}
+
+TEST(getpwnam, app_id_u0_a9999) {
+  CHECK_GETPWNAM_FOR("u0_a9999", 19999, TYPE_APP);
+}
+
+// nonsensical, but expected
+TEST(getpwnam, app_id_u1_root) {
+  CHECK_GETPWNAM_FOR("u1_root", 100000, TYPE_SYSTEM);
+}
+
+TEST(getpwnam, app_id_u1_radio) {
+  CHECK_GETPWNAM_FOR("u1_radio", 101001, TYPE_SYSTEM);
+}
+
+TEST(getpwnam, app_id_u1_a0) {
+  CHECK_GETPWNAM_FOR("u1_a0", 110000, TYPE_APP);
+}
+
+TEST(getpwnam, app_id_u1_i0) {
+  CHECK_GETPWNAM_FOR("u1_i0", 199000, TYPE_APP);
+}
+
+#endif /* __BIONIC__ */