test: add basic integration tests

Signed-off-by: Justin Chadwell <me@jedevc.com>

tests/workers/backend.go

@@ -0,0 +1,26 @@
+package workers
+
+type backend struct {
+	builder string
+	context string
+}
+
+func (s *backend) Address() string {
+	return s.builder
+}
+
+func (s *backend) DockerAddress() string {
+	return s.context
+}
+
+func (s *backend) ContainerdAddress() string {
+	return ""
+}
+
+func (s *backend) Snapshotter() string {
+	return ""
+}
+
+func (s *backend) Rootless() bool {
+	return false
+}