Add tests and rename middleware to plugin

README.md

@@ -1,7 +1,7 @@
 # example
 
 The example middleware prints "example" on every query received. It can be used as documentation for
-writing external middleware and to test if external middleware compiles with CoreDNS.
+writing external plugins and to test if external plugins compile with CoreDNS.
 
 ## Syntax
 
@@ -11,7 +11,7 @@ example
 
 ## Examples
 
-```
+``` corefile
 example.com {
   file example.com.db {
     upstream 8.8.8.8

example.go

@@ -1,23 +1,25 @@
-// The example middleware prints example to stdout on every packet received.
+// The example plugin prints example to stdout on every packet received.
 package example
 
 import (
 	"fmt"
+	"io"
+	"os"
 
 	"github.com/coredns/coredns/plugin"
 	"github.com/miekg/dns"
 	"golang.org/x/net/context"
 )
 
-// Example is an example middleware to ...
+// Example is an example plugin to show how to write a plugin.
 type Example struct {
 	Next plugin.Handler
 }
 
-// ServeDNS implements the middleware.Handler interface.
+// ServeDNS implements the plugin.Handler interface.
 func (e Example) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
 	// Somewhat convoluted, as we could have printed "example" here and just call
-	// the next middleware - but as an example, show how to wrap a ResponseWriter might be
+	// the next plugin - but as an example, show how to wrap a ResponseWriter might be
 	// educational.
 	pw := NewResponsePrinter(w)
 	return plugin.NextOrFailure(e.Name(), e.Next, ctx, pw, r)
@@ -37,6 +39,8 @@ func NewResponsePrinter(w dns.ResponseWriter) *ResponsePrinter {
 
 // WriteMsg records the status code and calls the underlying ResponseWriter's WriteMsg method.
 func (r *ResponsePrinter) WriteMsg(res *dns.Msg) error {
-	fmt.Println("example")
+	fmt.Fprintf(out, "example")
 	return r.ResponseWriter.WriteMsg(res)
 }
+
+var out io.Writer = os.Stdout

example_test.go

@@ -0,0 +1,29 @@
+package example
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/coredns/coredns/plugin/pkg/dnstest"
+	"github.com/coredns/coredns/plugin/test"
+
+	"github.com/miekg/dns"
+	"golang.org/x/net/context"
+)
+
+func TestExample(t *testing.T) {
+	ex := Example{Next: test.ErrorHandler()}
+
+	b := &bytes.Buffer{}
+	out = b
+
+	ctx := context.TODO()
+	r := new(dns.Msg)
+	r.SetQuestion("example.org.", dns.TypeA)
+	rec := dnstest.NewRecorder(&test.ResponseWriter{})
+
+	ex.ServeDNS(ctx, rec, r)
+	if x := b.String(); x != "example" {
+		t.Errorf("Failed to print 'example', got %s", x)
+	}
+}

setup_test.go

@@ -0,0 +1,19 @@
+package example
+
+import (
+	"testing"
+
+	"github.com/mholt/caddy"
+)
+
+func TestSetupWhoami(t *testing.T) {
+	c := caddy.NewTestController("dns", `example`)
+	if err := setup(c); err != nil {
+		t.Fatalf("Expected no errors, but got: %v", err)
+	}
+
+	c = caddy.NewTestController("dns", `example more`)
+	if err := setup(c); err == nil {
+		t.Fatalf("Expected errors, but got: %v", err)
+	}
+}