tests: make it possible to simluate wget failure

Make it possible to simulate wget errors by fetching an URL with 'fail'
or '404' in the URL string. 'fail' results in DNS error(ish) and '404'
returns a 404 error message.

tests/bin/wget

@@ -63,6 +63,13 @@ while true; do
 	shift
 done
 
+for url; do
+	case "$url" in
+		*fail*) msg "bad address"; exit 1;;
+		*404*) msg "wget: server returned error: HTTP/1.1 404 Not Found"; exit 1;;
+	esac
+done
+
 : ${outfile:=index.html}
 case "$outfile" in
 	-)	msg "writing to stdout"

tests/fake_wget_test

@@ -7,7 +7,9 @@ init_tests \
 	fake_wget_quiet \
 	fake_wget \
 	fake_wget_outfile \
-	fake_wget_stdout
+	fake_wget_stdout \
+	fake_wget_fail \
+	fake_wget_404
 
 fake_wget_usage_body() {
 	test_usage wget
@@ -56,3 +58,18 @@ fake_wget_stdout_body() {
 		wget -O - https://example.com
 		! test -f - || atf_fail "- was created"
 }
+
+fake_wget_fail_body() {
+	init_env
+	atf_check -s exit:1 \
+		-e match:"bad address" \
+		wget https://example.com/fail
+}
+
+fake_wget_404_body() {
+	init_env
+	atf_check -s exit:1 \
+		-e match:"404 Not Found" \
+		wget https://example.com/404
+}
+