Return failure if any of install_modules fails

Add test to verify that install_modules can be skipped and that
install_modules returns failure if it fails to update mdev.conf.

lib/tiny-cloud/init-early

@@ -27,16 +27,17 @@ has_cloud_hotplugs() { [ -n "$HOTPLUG_MODULES" ]; }
 install_hotplugs() {
     skip_action install_hotplugs && return
 
-    local result
+    local result rc=0
 
     for module in $HOTPLUG_MODULES; do
         result='-'
         echo -n " $module"
         if type "mod__$module" | grep -q "is a function"; then
-            "mod__$module" && result='+' || result='!'
+            "mod__$module" && result='+' || { result='!'; rc=1; }
         fi
         echo -n "($result)"
     done
+    return $rc
 }
 
 : "${HOTPLUG_TYPE:=mdev}"

tests/init-early.test

@@ -8,7 +8,9 @@ export MOCK=echo
 init_tests \
 	expand_root \
 	expand_root_partition \
-	expand_root_skip
+	expand_root_skip \
+	install_hotplugs_skip \
+	install_hotplugs_fail
 
 PROVIDERS="aws azure gcp nocloud oci"
 
@@ -64,3 +66,29 @@ expand_root_skip_body() {
 	done
 }
 
+install_hotplugs_skip_body() {
+	fake_bin test-install-hotplugs <<-EOF
+		#!/bin/sh
+		SKIP_INIT_ACTIONS=install_hotplugs
+		. "$srcdir"/lib/tiny-cloud/init-early
+		install_hotplugs
+	EOF
+	for provider in $PROVIDERS; do
+		CLOUD="$provider" atf_check \
+			-o match:'^ SKIPPING$' \
+			test-install-hotplugs
+	done
+}
+
+install_hotplugs_fail_body() {
+	fake_bin test-install-hotplugs <<-EOF
+		#!/bin/sh
+		HOTPLUG_MODULES="vnic_eth_hotplug"
+		. "$srcdir"/lib/tiny-cloud/init-early
+		install_hotplugs
+	EOF
+	CLOUD=aws atf_check -s not-exit:0 \
+		-o match:"^ vnic_eth_hotplug\(!\)$" \
+		test-install-hotplugs
+}
+