2 files changed, 117 insertions, 3 deletions
diff --git a/middleware/secondary/README.md b/middleware/secondary/README.md
index 7d5338c95..d6cbe465a 100644
--- a/middleware/secondary/README.md
+++ b/middleware/secondary/README.md
@@ -31,9 +31,24 @@ secondary [zones...] {
 
 ## Examples
 
+Transfer `example.org` from 10.0.1.1, and if that fails try 10.1.2.1.
+
+~~~ corefile
+example.org {
+    secondary {
+        transfer from 10.0.1.1
+        transfer from 10.1.2.1
+    }
+}
 ~~~
-secondary example.org {
-    transfer from 10.0.1.1
-    transfer from 10.1.2.1
+
+Or re-export the retrieved zone to other secondaries.
+
+~~~ corefile
+. {
+    secondary example.net {
+        transfer from 10.1.2.1
+        transfer to *
+    }
 }
 ~~~
diff --git a/test/readme_test.go b/test/readme_test.go
new file mode 100644
index 000000000..f231ebc5a
--- /dev/null
+++ b/test/readme_test.go
@@ -0,0 +1,99 @@
+package test
+
+import (
+	"bufio"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/coredns/coredns/core/dnsserver"
+
+	"github.com/mholt/caddy"
+)
+
+// Pasrse all README.md's of the middleware and check if every example Corefile
+// actually works. Each corefile is only used if:
+//
+// ~~~ corefile
+// . {
+//	# check-this-please
+// }
+// ~~~
+
+func TestReadme(t *testing.T) {
+	caddy.Quiet = true
+	dnsserver.Quiet = true
+	dnsserver.Port = "10053"
+	log.SetOutput(ioutil.Discard)
+
+	middle := filepath.Join("..", "middleware")
+	dirs, err := ioutil.ReadDir(middle)
+	if err != nil {
+		t.Fatalf("Could not read %s: %q", middle, err)
+	}
+	for _, d := range dirs {
+		if !d.IsDir() {
+			continue
+		}
+		readme := filepath.Join(middle, d.Name())
+		readme = filepath.Join(readme, "README.md")
+
+		inputs, err := corefileFromReadme(readme)
+		if err != nil {
+			continue
+		}
+
+		// Test each snippet.
+		for _, in := range inputs {
+			t.Logf("Testing %s, with %d byte snippet", readme, len(in.Body()))
+			server, err := caddy.Start(in)
+			if err != nil {
+				t.Errorf("Failed to start server for input %q:\n%s", err, in.Body())
+			}
+			server.Stop()
+		}
+	}
+}
+
+// corefileFromReadme parses a readme and returns all fragments that
+// have ~~~ corefile (or ``` corefile).
+func corefileFromReadme(readme string) ([]*Input, error) {
+	f, err := os.Open(readme)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(f)
+	input := []*Input{}
+	corefile := false
+	temp := ""
+
+	for s.Scan() {
+		line := s.Text()
+		if line == "~~~ corefile" || line == "``` corefile" {
+			corefile = true
+			continue
+		}
+
+		if corefile && (line == "~~~" || line == "```") {
+			// last line
+			input = append(input, NewInput(temp))
+
+			temp = ""
+			corefile = false
+			continue
+		}
+
+		if corefile {
+			temp += line + "\n" // readd newline stripped by s.Text()
+		}
+	}
+
+	if err := s.Err(); err != nil {
+		return nil, err
+	}
+	return input, nil
+}