Add an extra test

actions/testdata/buildfail-action/Dockerfile

@@ -0,0 +1,2 @@
+FROM alpine:3.8
+COPY foobar /foo/bar

actions/testdata/buildfail.workflow

@@ -0,0 +1,8 @@
+workflow "test" {
+  on = "push"
+  resolves = ["test-action"]
+}
+
+action "test-action" {
+  uses = "./buildfail-action"
+}