Convert ethtool.c to use kselftest_harness.h with FIXTURE/TEST_F.
Move ethtool from BINS to TEST_GEN_FILES and add ethtool.sh wrapper
which sets up a netdevsim device before running the test binary.

Output:

  TAP version 13
  1..2
  # Starting 2 tests from 1 test cases.
  #  RUN           ethtool.channels ...
  #    nsim0: combined 1
  #            OK  ethtool.channels
  ok 1 ethtool.channels
  #  RUN           ethtool.rings ...
  #    nsim0: rx 512 tx 512
  #            OK  ethtool.rings
  ok 2 ethtool.rings
  # PASSED: 2 / 2 tests passed.
  # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 tools/net/ynl/tests/Makefile   |  3 +-
 tools/net/ynl/tests/ethtool.c  | 83 ++++++++++++++++++++++------------
 tools/net/ynl/tests/ethtool.sh |  5 ++
 3 files changed, 62 insertions(+), 29 deletions(-)
 create mode 100755 tools/net/ynl/tests/ethtool.sh

diff --git a/tools/net/ynl/tests/Makefile b/tools/net/ynl/tests/Makefile
index 14d399a70f10..c380e9f331a3 100644
--- a/tools/net/ynl/tests/Makefile
+++ b/tools/net/ynl/tests/Makefile
@@ -15,6 +15,7 @@ LDLIBS=../lib/ynl.a ../generated/protos.a
 
 TEST_PROGS := \
 	devlink.sh \
+	ethtool.sh \
 	test_ynl_cli.sh \
 	test_ynl_ethtool.sh \
 # end of TEST_PROGS
@@ -28,10 +29,10 @@ TEST_GEN_PROGS := \
 
 TEST_GEN_FILES := \
 	devlink \
+	ethtool \
 # end of TEST_GEN_FILES
 
 BINS := \
-	ethtool \
 	rt-addr \
 	rt-route \
 # end of BINS
diff --git a/tools/net/ynl/tests/ethtool.c b/tools/net/ynl/tests/ethtool.c
index a7ebbd1b98db..926a75d23c9b 100644
--- a/tools/net/ynl/tests/ethtool.c
+++ b/tools/net/ynl/tests/ethtool.c
@@ -6,28 +6,49 @@
 
 #include <net/if.h>
 
+#include <kselftest_harness.h>
+
 #include "ethtool-user.h"
 
-int main(int argc, char **argv)
+FIXTURE(ethtool)
+{
+	struct ynl_sock *ys;
+};
+
+FIXTURE_SETUP(ethtool)
+{
+	self->ys = ynl_sock_create(&ynl_ethtool_family, NULL);
+	ASSERT_NE(NULL, self->ys)
+		TH_LOG("failed to create ethtool socket");
+}
+
+FIXTURE_TEARDOWN(ethtool)
+{
+	ynl_sock_destroy(self->ys);
+}
+
+TEST_F(ethtool, channels)
 {
 	struct ethtool_channels_get_req_dump creq = {};
-	struct ethtool_rings_get_req_dump rreq = {};
 	struct ethtool_channels_get_list *channels;
-	struct ethtool_rings_get_list *rings;
-	struct ynl_sock *ys;
 
-	ys = ynl_sock_create(&ynl_ethtool_family, NULL);
-	if (!ys)
-		return 1;
+	creq._present.header = 1; /* ethtool needs an empty nest */
+	channels = ethtool_channels_get_dump(self->ys, &creq);
+	ASSERT_NE(NULL, channels) {
+		TH_LOG("channels dump failed: %s", self->ys->err.msg);
+	}
 
-	creq._present.header = 1; /* ethtool needs an empty nest, sigh */
-	channels = ethtool_channels_get_dump(ys, &creq);
-	if (!channels)
-		goto err_close;
+	if (ynl_dump_empty(channels)) {
+		ethtool_channels_get_list_free(channels);
+		SKIP(return, "no entries in channels dump");
+	}
 
-	printf("Channels:\n");
 	ynl_dump_foreach(channels, dev) {
-		printf("  %8s: ", dev->header.dev_name);
+		EXPECT_TRUE((bool)dev->header._len.dev_name);
+		ksft_print_msg("%8s: ", dev->header.dev_name);
+		EXPECT_TRUE(dev->_present.rx_count ||
+			    dev->_present.tx_count ||
+			    dev->_present.combined_count);
 		if (dev->_present.rx_count)
 			printf("rx %d ", dev->rx_count);
 		if (dev->_present.tx_count)
@@ -37,15 +58,28 @@ int main(int argc, char **argv)
 		printf("\n");
 	}
 	ethtool_channels_get_list_free(channels);
+}
 
-	rreq._present.header = 1; /* ethtool needs an empty nest.. */
-	rings = ethtool_rings_get_dump(ys, &rreq);
-	if (!rings)
-		goto err_close;
+TEST_F(ethtool, rings)
+{
+	struct ethtool_rings_get_req_dump rreq = {};
+	struct ethtool_rings_get_list *rings;
+
+	rreq._present.header = 1; /* ethtool needs an empty nest */
+	rings = ethtool_rings_get_dump(self->ys, &rreq);
+	ASSERT_NE(NULL, rings) {
+		TH_LOG("rings dump failed: %s", self->ys->err.msg);
+	}
+
+	if (ynl_dump_empty(rings)) {
+		ethtool_rings_get_list_free(rings);
+		SKIP(return, "no entries in rings dump");
+	}
 
-	printf("Rings:\n");
 	ynl_dump_foreach(rings, dev) {
-		printf("  %8s: ", dev->header.dev_name);
+		EXPECT_TRUE((bool)dev->header._len.dev_name);
+		ksft_print_msg("%8s: ", dev->header.dev_name);
+		EXPECT_TRUE(dev->_present.rx || dev->_present.tx);
 		if (dev->_present.rx)
 			printf("rx %d ", dev->rx);
 		if (dev->_present.tx)
@@ -53,13 +87,6 @@ int main(int argc, char **argv)
 		printf("\n");
 	}
 	ethtool_rings_get_list_free(rings);
-
-	ynl_sock_destroy(ys);
-
-	return 0;
-
-err_close:
-	fprintf(stderr, "YNL (%d): %s\n", ys->err.code, ys->err.msg);
-	ynl_sock_destroy(ys);
-	return 2;
 }
+
+TEST_HARNESS_MAIN
diff --git a/tools/net/ynl/tests/ethtool.sh b/tools/net/ynl/tests/ethtool.sh
new file mode 100755
index 000000000000..b4f0b2a707bc
--- /dev/null
+++ b/tools/net/ynl/tests/ethtool.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+source "$(dirname "$(realpath "$0")")/ynl_nsim_lib.sh"
+nsim_setup
+exec "$(dirname "$(realpath "$0")")/ethtool"
-- 
2.53.0