mw/autopath: integration test with erratic (#930)

Add integration test with erratic. For this erratic now also returns an
autopath searchpath. This tests the whole chain; i.e registring a
searchfunction and calling that from autopath.

This tests does a autopathing domain and a non-autopathing one.

middleware/erratic/README.md

@@ -7,6 +7,9 @@ The *erratic* middleware will respond to every A or AAAA query. For any other ty
 a SERVFAIL response. The reply for A will return 192.0.2.53 (see RFC 5737), for AAAA it returns
 2001:DB8::53 (see RFC 3849).
 
+*erratic* can also be used in conjunction with the *autopath* middleware. This is mostly to aid in
+ testing.
+
 ## Syntax
 
 ~~~ txt

middleware/erratic/autopath.go

@@ -0,0 +1,8 @@
+package erratic
+
+import "github.com/coredns/coredns/request"
+
+// AutoPath implements the AutoPathFunc call from the autopath middleware.
+func (e *Erratic) AutoPath(state request.Request) []string {
+	return []string{"a.example.org.", "b.example.org.", ""}
+}

middleware/erratic/setup.go

@@ -28,6 +28,9 @@ func setupErratic(c *caddy.Controller) error {
 		return e
 	})
 
+	// Also register erratic for use in autopath.
+	dnsserver.GetConfig(c).RegisterHandler(e)
+
 	return nil
 }