REGTESTS: stats: add test stats-file counters preload

Define a simple regtest to check stats-file loading on startup. A sample
stats-file is written with some invalid values which should be silently
ignored.

reg-tests/stats/sample-stats-file

@@ -0,0 +1,26 @@
+#fe guid,stot,
+
+// valid line
+guid-fe,1024,
+
+// invalid non numerical value must be silently ignored
+guid-fe,abc,
+
+// listener counters not allocated if no option socket-stats
+guid-feS-0,1024
+guid-fe2S-0,1024
+
+// unknown GUID must be silently ignored
+guid-unknown,1024,
+
+// invalid GUID side must be silently ignored
+guid-be,1024
+
+// unknown section line must be silently ignored
+#inval guid,other,
+guid-foo,0,0,
+
+// valid lines
+#be guid,unknown,stot,
+guid-be,512,1024,
+guid-srv,512,1024,

reg-tests/stats/stats-file.vtc

@@ -0,0 +1,36 @@
+varnishtest "Preload counters via stats-file"
+
+feature ignore_unknown_macro
+
+#REQUIRE_VERSION=3.0
+
+haproxy h1 -conf {
+	global
+		stats-file ${testdir}/sample-stats-file
+
+	frontend fe
+		guid guid-fe
+		bind "fd@${feS}" guid-prefix guid-feS
+
+	frontend fe2
+		guid guid-fe2
+		option socket-stats
+		bind "fd@${fe2S}" guid-prefix guid-fe2S
+
+	backend be
+		guid guid-be
+		server srv ${s1_addr}:${s1_port} guid guid-srv
+} -start
+
+haproxy h1 -cli {
+	send "show stat fe 15 -1 typed"
+	expect ~ "F.*.*.*.stot.1:MCP:u64:1024"
+
+	send "show stat fe2 15 -1 typed"
+	expect ~ "L.*.*.*.stot.1:MCP:u64:1024"
+
+	send "show stat be 15 -1 typed"
+	expect ~ "B.*.*.*.stot.1:MCP:u64:1024"
+	send "show stat be 15 -1 typed"
+	expect ~ "S.*.*.*.stot.1:MCP:u64:1024"
+}