diff --git a/tests/util/id/Atffile b/tests/util/id/Atffile
new file mode 100644
index 000000000000..c36d8cdb7be8
--- /dev/null
+++ b/tests/util/id/Atffile
@@ -0,0 +1,5 @@
+Content-Type: application/X-atf-atffile; version="1"
+
+prop: test-suite = "NetBSD"
+
+tp-glob: t_*
diff --git a/tests/util/id/Makefile b/tests/util/id/Makefile
new file mode 100644
index 000000000000..0081c8f86138
--- /dev/null
+++ b/tests/util/id/Makefile
@@ -0,0 +1,12 @@
+# $NetBSD: Makefile,v 1.1 2007/11/16 18:06:46 jmmv Exp $
+
+.include <bsd.own.mk>
+
+SUBDIR=		libfake
+
+TESTS_SH=	t_groups
+TESTS_SH+=	t_id
+TESTS_SH+=	t_whoami
+
+.include <bsd.test.mk>
+.include <bsd.subdir.mk>
diff --git a/tests/util/id/libfake/Makefile b/tests/util/id/libfake/Makefile
new file mode 100644
index 000000000000..bd4f4a7579fd
--- /dev/null
+++ b/tests/util/id/libfake/Makefile
@@ -0,0 +1,22 @@
+# $NetBSD: Makefile,v 1.1 2007/11/16 18:06:47 jmmv Exp $
+
+.include <bsd.own.mk>
+
+# XXX This installs too much "garbage" in the destination directory, such as
+# the libfake_pic.a and libfake.so files.  We only need a shared object that
+# we can later LD_PRELOAD, but I don't know how to do this from our current
+# bsd.lib.mk (or, for that matter, any other .mk file).
+
+LIB=	fake
+SRCS=	pwgr.c
+
+MKLINKLIB=	no
+MKSTATICLIB=	no
+MKPIC=		yes
+MKPROFILE=	no
+SHLIB_MAJOR=	0
+SHLIB_MINOR=	0
+LIBDIR=		/usr/tests/util/id
+
+.include <bsd.lib.mk>
+.include <bsd.subdir.mk>
diff --git a/tests/util/id/libfake/pwgr.c b/tests/util/id/libfake/pwgr.c
new file mode 100644
index 000000000000..bc0440d69f4d
--- /dev/null
+++ b/tests/util/id/libfake/pwgr.c
@@ -0,0 +1,193 @@
+/* $NetBSD: pwgr.c,v 1.1 2007/11/16 18:06:47 jmmv Exp $ */
+/*
+ * Copyright (c) 2007 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * This file implements replacements for all user/group-related functions
+ * called by id(1).  It provides fake but deterministic user and group
+ * information.  The details are as such:
+ * User root, uid 0, primary group 0 (wheel).
+ * User test, uid 100, primary group 100 (users), secondary group 0 (wheel).
+ */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <grp.h>
+#include <pwd.h>
+#include <stdlib.h>
+#include <string.h>
+
+char Login[16];
+struct group GrEntry;
+struct passwd PwEntry;
+
+gid_t
+getgid(void)
+{
+	return 100;
+}
+
+gid_t
+getegid(void)
+{
+	if (getenv("LIBFAKE_EGID_ROOT") != NULL)
+		return 0;
+	else
+		return 100;
+}
+
+uid_t
+getuid(void)
+{
+	return 100;
+}
+
+uid_t
+geteuid(void)
+{
+	if (getenv("LIBFAKE_EUID_ROOT") != NULL)
+		return 0;
+	else
+		return 100;
+}
+
+char *
+getlogin(void)
+{
+	strcpy(Login, "test");
+	return Login;
+}
+
+struct group *
+getgrgid(gid_t gid)
+{
+	struct group *g = &GrEntry;
+
+	memset(g, 0, sizeof(*g));
+	if (gid == 0) {
+		g->gr_name = "wheel";
+		g->gr_gid = 0;
+	} else if (gid == 100) {
+		g->gr_name = "users";
+		g->gr_gid = 100;
+	} else
+		g = NULL;
+
+	return g;
+}
+
+int
+getgrouplist(const char *name, int basegid, int *groups, int *ngroups)
+{
+	int cnt, ret;
+
+	if (name == "root") {
+		if (*ngroups >= 1) {
+			groups[0] = basegid;
+			cnt = 1;
+		}
+
+		ret = (*ngroups >= cnt) ? 0 : -1;
+		*ngroups = cnt;
+	} else if (name == "test") {
+		if (*ngroups >= 1) {
+			groups[0] = basegid;
+			cnt = 1;
+		}
+
+		if (*ngroups >= 2) {
+			groups[1] = 0;
+			cnt = 2;
+		}
+
+		ret = (*ngroups >= cnt) ? 0 : -1;
+		*ngroups = cnt;
+	} else
+		ret = -1;
+
+	return ret;
+}
+
+int
+getgroups(int gidsetlen, gid_t *gidset)
+{
+	if (gidsetlen < 2) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	gidset[0] = 100;
+	gidset[1] = 0;
+	return 2;
+}
+
+struct passwd *
+getpwnam(const char *login)
+{
+	struct passwd *p = &PwEntry;
+
+	memset(p, 0, sizeof(*p));
+	if (strcmp(login, "root") == 0) {
+		p->pw_name = "root";
+		p->pw_uid = 0;
+		p->pw_gid = 0;
+	} else if (strcmp(login, "test") == 0) {
+		p->pw_name = "test";
+		p->pw_uid = 100;
+		p->pw_gid = 100;
+	} else
+		p = NULL;
+
+	return p;
+}
+
+struct passwd *
+getpwuid(uid_t uid)
+{
+	struct passwd *p = &PwEntry;
+
+	memset(p, 0, sizeof(*p));
+	if (uid == 0) {
+		p->pw_name = "root";
+		p->pw_uid = 0;
+		p->pw_gid = 0;
+	} else if (uid == 100) {
+		p->pw_name = "test";
+		p->pw_uid = 100;
+		p->pw_gid = 100;
+	} else
+		p = NULL;
+
+	return p;
+}
diff --git a/tests/util/id/t_groups.sh b/tests/util/id/t_groups.sh
new file mode 100644
index 000000000000..35967585a595
--- /dev/null
+++ b/tests/util/id/t_groups.sh
@@ -0,0 +1,69 @@
+# $NetBSD: t_groups.sh,v 1.1 2007/11/16 18:06:46 jmmv Exp $
+#
+# Copyright (c) 2007 The NetBSD Foundation, Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+# 3. All advertising materials mentioning features or use of this software
+#    must display the following acknowledgement:
+#        This product includes software developed by the NetBSD
+#        Foundation, Inc. and its contributors.
+# 4. Neither the name of The NetBSD Foundation nor the names of its
+#    contributors may be used to endorse or promote products derived
+#    from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+# ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+
+run_groups() {
+	LD_PRELOAD=$(atf_get_srcdir)/libfake.so.0 groups "${@}"
+}
+
+atf_test_case correct
+correct_head() {
+	atf_set "descr" "Checks that correct queries work"
+}
+correct_body() {
+	echo "users wheel" >expout
+	atf_check "run_groups" 0 expout null
+	atf_check "run_groups 100" 0 expout null
+	atf_check "run_groups test" 0 expout null
+
+	echo "wheel" >expout
+	atf_check "run_groups 0" 0 expout null
+	atf_check "run_groups root" 0 expout null
+}
+
+atf_test_case syntax
+syntax_head() {
+	atf_set "descr" "Checks the command's syntax"
+}
+syntax_body() {
+	# Give an invalid flag but which is allowed by id (with which
+	# groups shares code) when using the -Gn options.
+	atf_check "run_groups -r" 1 null stderr
+	atf_check "grep '^usage:' stderr" 0 ignore null
+}
+
+atf_init_test_cases()
+{
+	atf_add_test_case correct
+	atf_add_test_case syntax
+}
diff --git a/tests/util/id/t_id.sh b/tests/util/id/t_id.sh
new file mode 100644
index 000000000000..10c81e3576f7
--- /dev/null
+++ b/tests/util/id/t_id.sh
@@ -0,0 +1,292 @@
+# $NetBSD: t_id.sh,v 1.1 2007/11/16 18:06:46 jmmv Exp $
+#
+# Copyright (c) 2007 The NetBSD Foundation, Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+# 3. All advertising materials mentioning features or use of this software
+#    must display the following acknowledgement:
+#        This product includes software developed by the NetBSD
+#        Foundation, Inc. and its contributors.
+# 4. Neither the name of The NetBSD Foundation nor the names of its
+#    contributors may be used to endorse or promote products derived
+#    from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+# ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+
+run_id() {
+	LD_PRELOAD=$(atf_get_srcdir)/libfake.so.0 id "${@}"
+}
+
+atf_test_case default
+default_head() {
+	atf_set "descr" "Checks that the output without options is correct"
+}
+default_body() {
+	echo "uid=100(test) gid=100(users) groups=100(users),0(wheel)" >expout
+	atf_check "run_id" 0 expout null
+	atf_check "run_id 100" 0 expout null
+	atf_check "run_id test" 0 expout null
+
+	echo "uid=0(root) gid=0(wheel) groups=0(wheel)" >expout
+	atf_check "run_id 0" 0 expout null
+	atf_check "run_id root" 0 expout null
+
+	export LIBFAKE_EGID_ROOT=1 LIBFAKE_EUID_ROOT=1
+	echo "uid=100(test) gid=100(users) euid=0(root) egid=0(wheel) groups=100(users),0(wheel)" >expout
+	atf_check "run_id" 0 expout null
+	unset LIBFAKE_EGID_ROOT LIBFAKE_EUID_ROOT
+
+	echo 'id: nonexistent: No such user' >experr
+	atf_check "run_id nonexistent" 1 null experr
+
+	atf_check "run_id root nonexistent" 1 null stderr
+	atf_check "grep ^usage: stderr" 0 ignore null
+}
+
+atf_test_case primaries
+primaries_head() {
+	atf_set "descr" "Checks that giving multiple primaries" \
+	                "simultaneously provides an error"
+}
+primaries_body() {
+	for p1 in -G -g -p -u; do
+		for p2 in -G -g -p -u; do
+			if [ ${p1} != ${p2} ]; then
+				atf_check "run_id ${p1} ${p2}" 1 null stderr
+				atf_check "grep ^usage: stderr" 0 ignore null
+			fi
+		done
+	done
+}
+
+atf_test_case Gflag
+Gflag_head() {
+	atf_set "descr" "Checks that the -G primary flag works"
+}
+Gflag_body() {
+	echo "100 0" >expout
+	atf_check "run_id -G" 0 expout null
+	atf_check "run_id -G 100" 0 expout null
+	atf_check "run_id -G test" 0 expout null
+
+	echo "users wheel" >expout
+	atf_check "run_id -G -n" 0 expout null
+	atf_check "run_id -G -n 100" 0 expout null
+	atf_check "run_id -G -n test" 0 expout null
+
+	echo "0" >expout
+	atf_check "run_id -G 0" 0 expout null
+	atf_check "run_id -G root" 0 expout null
+
+	echo "wheel" >expout
+	atf_check "run_id -G -n 0" 0 expout null
+	atf_check "run_id -G -n root" 0 expout null
+
+	echo 'id: nonexistent: No such user' >experr
+	atf_check "run_id -G nonexistent" 1 null experr
+
+	atf_check "run_id -G root nonexistent" 1 null stderr
+	atf_check "grep ^usage: stderr" 0 ignore null
+}
+
+atf_test_case gflag
+gflag_head() {
+	atf_set "descr" "Checks that the -g primary flag works"
+}
+gflag_body() {
+	echo "100" >expout
+	atf_check "run_id -g" 0 expout null
+	atf_check "run_id -g 100" 0 expout null
+	atf_check "run_id -g test" 0 expout null
+
+	echo "users" >expout
+	atf_check "run_id -g -n" 0 expout null
+	atf_check "run_id -g -n 100" 0 expout null
+	atf_check "run_id -g -n test" 0 expout null
+
+	echo "0" >expout
+	atf_check "run_id -g 0" 0 expout null
+	atf_check "run_id -g root" 0 expout null
+
+	echo "wheel" >expout
+	atf_check "run_id -g -n 0" 0 expout null
+	atf_check "run_id -g -n root" 0 expout null
+
+	echo "100" >expout
+	atf_check "run_id -g -r" 0 expout null
+
+	echo "users" >expout
+	atf_check "run_id -g -r -n" 0 expout null
+
+	echo "100" >expout
+	atf_check "run_id -g -r 100" 0 expout null
+	atf_check "run_id -g -r test" 0 expout null
+
+	echo "users" >expout
+	atf_check "run_id -g -r -n 100" 0 expout null
+	atf_check "run_id -g -r -n test" 0 expout null
+
+	export LIBFAKE_EGID_ROOT=1 LIBFAKE_EUID_ROOT=1
+
+	echo "0" >expout
+	atf_check "run_id -g" 0 expout null
+
+	echo "wheel" >expout
+	atf_check "run_id -g -n" 0 expout null
+
+	echo "100" >expout
+	atf_check "run_id -g -r" 0 expout null
+
+	echo "users" >expout
+	atf_check "run_id -g -r -n" 0 expout null
+
+	echo "100" >expout
+	atf_check "run_id -g -r 100" 0 expout null
+	atf_check "run_id -g -r test" 0 expout null
+
+	echo "users" >expout
+	atf_check "run_id -g -r -n 100" 0 expout null
+	atf_check "run_id -g -r -n test" 0 expout null
+
+	unset LIBFAKE_EGID_ROOT LIBFAKE_EUID_ROOT
+
+	echo 'id: nonexistent: No such user' >experr
+	atf_check "run_id -g nonexistent" 1 null experr
+
+	atf_check "run_id -g root nonexistent" 1 null stderr
+	atf_check "grep ^usage: stderr" 0 ignore null
+}
+
+atf_test_case pflag
+pflag_head() {
+	atf_set "descr" "Checks that the -p primary flag works"
+}
+pflag_body() {
+	cat >expout <<EOF
+uid	test
+groups	users wheel
+EOF
+	atf_check "run_id -p" 0 expout null
+	atf_check "run_id -p 100" 0 expout null
+	atf_check "run_id -p test" 0 expout null
+
+	cat >expout <<EOF
+uid	root
+groups	wheel
+EOF
+	atf_check "run_id -p 0" 0 expout null
+	atf_check "run_id -p root" 0 expout null
+
+	export LIBFAKE_EGID_ROOT=1 LIBFAKE_EUID_ROOT=1
+	cat >expout <<EOF
+uid	test
+euid	root
+rgid	users
+groups	users wheel
+EOF
+	atf_check "run_id -p" 0 expout null
+	unset LIBFAKE_EGID_ROOT LIBFAKE_EUID_ROOT
+
+	echo 'id: nonexistent: No such user' >experr
+	atf_check "run_id -p nonexistent" 1 null experr
+
+	atf_check "run_id -p root nonexistent" 1 null stderr
+	atf_check "grep ^usage: stderr" 0 ignore null
+}
+
+atf_test_case uflag
+uflag_head() {
+	atf_set "descr" "Checks that the -u primary flag works"
+}
+uflag_body() {
+	echo "100" >expout
+	atf_check "run_id -u" 0 expout null
+	atf_check "run_id -u 100" 0 expout null
+	atf_check "run_id -u test" 0 expout null
+
+	echo "test" >expout
+	atf_check "run_id -u -n" 0 expout null
+	atf_check "run_id -u -n 100" 0 expout null
+	atf_check "run_id -u -n test" 0 expout null
+
+	echo "0" >expout
+	atf_check "run_id -u 0" 0 expout null
+	atf_check "run_id -u root" 0 expout null
+
+	echo "root" >expout
+	atf_check "run_id -u -n 0" 0 expout null
+	atf_check "run_id -u -n root" 0 expout null
+
+	echo "100" >expout
+	atf_check "run_id -u -r" 0 expout null
+
+	echo "test" >expout
+	atf_check "run_id -u -r -n" 0 expout null
+
+	echo "100" >expout
+	atf_check "run_id -u -r 100" 0 expout null
+	atf_check "run_id -u -r test" 0 expout null
+
+	echo "test" >expout
+	atf_check "run_id -u -r -n 100" 0 expout null
+	atf_check "run_id -u -r -n test" 0 expout null
+
+	export LIBFAKE_EGID_ROOT=1 LIBFAKE_EUID_ROOT=1
+
+	echo "0" >expout
+	atf_check "run_id -u" 0 expout null
+
+	echo "root" >expout
+	atf_check "run_id -u -n" 0 expout null
+
+	echo "100" >expout
+	atf_check "run_id -u -r" 0 expout null
+
+	echo "test" >expout
+	atf_check "run_id -u -r -n" 0 expout null
+
+	echo "100" >expout
+	atf_check "run_id -u -r 100" 0 expout null
+	atf_check "run_id -u -r test" 0 expout null
+
+	echo "test" >expout
+	atf_check "run_id -u -r -n 100" 0 expout null
+	atf_check "run_id -u -r -n test" 0 expout null
+
+	unset LIBFAKE_EGID_ROOT LIBFAKE_EUID_ROOT
+
+	echo 'id: nonexistent: No such user' >experr
+	atf_check "run_id -u nonexistent" 1 null experr
+
+	atf_check "run_id -u root nonexistent" 1 null stderr
+	atf_check "grep ^usage: stderr" 0 ignore null
+}
+
+atf_init_test_cases()
+{
+	atf_add_test_case default
+	atf_add_test_case primaries
+	atf_add_test_case Gflag
+	atf_add_test_case gflag
+	atf_add_test_case pflag
+	atf_add_test_case uflag
+}
diff --git a/tests/util/id/t_whoami.sh b/tests/util/id/t_whoami.sh
new file mode 100644
index 000000000000..bff21d90c12e
--- /dev/null
+++ b/tests/util/id/t_whoami.sh
@@ -0,0 +1,73 @@
+# $NetBSD: t_whoami.sh,v 1.1 2007/11/16 18:06:46 jmmv Exp $
+#
+# Copyright (c) 2007 The NetBSD Foundation, Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+# 3. All advertising materials mentioning features or use of this software
+#    must display the following acknowledgement:
+#        This product includes software developed by the NetBSD
+#        Foundation, Inc. and its contributors.
+# 4. Neither the name of The NetBSD Foundation nor the names of its
+#    contributors may be used to endorse or promote products derived
+#    from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+# ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+
+run_whoami() {
+	LD_PRELOAD=$(atf_get_srcdir)/libfake.so.0 whoami "${@}"
+}
+
+atf_test_case correct
+correct_head() {
+	atf_set "descr" "Checks that correct queries work"
+}
+correct_body() {
+	echo "Checking with EUID=100"
+	echo "test" >expout
+	atf_check "run_whoami" 0 expout null
+
+	echo "Checking with EUID=0"
+	export LIBFAKE_EUID_ROOT=1
+	echo "root" >expout
+	atf_check "run_whoami" 0 expout null
+}
+
+atf_test_case syntax
+syntax_head() {
+	atf_set "descr" "Checks the command's syntax"
+}
+syntax_body() {
+	# Give a user to the command.
+	echo 'usage: whoami' >experr
+	atf_check "run_whoami root" 1 null experr
+
+	# Give an invalid flag but which is allowed by id (with which
+	# whoami shares code) when using the -un options.
+	echo 'usage: whoami' >experr
+	atf_check "run_whoami -r" 1 null experr
+}
+
+atf_init_test_cases()
+{
+	atf_add_test_case correct
+	atf_add_test_case syntax
+}