add example and autodoc include in README

Author: lestrrat

README.md

@@ -10,50 +10,10 @@ Go's standard library does not include Ed448 support. The only viable implementa
 
 Import this package for its side effects to register Ed448 with `jwx`:
 
+<!-- INCLUDE(example_test.go) -->
 ```go
-package main
-
-import (
-	"fmt"
-
-	"github.com/cloudflare/circl/sign/ed448"
-	"github.com/lestrrat-go/jwx/v3/jwa"
-	"github.com/lestrrat-go/jwx/v3/jwk"
-	"github.com/lestrrat-go/jwx/v3/jws"
-
-	_ "github.com/lestrrat-go/jwx-circl-ed448" // register Ed448
-)
-
-func main() {
-	pub, priv, err := ed448.GenerateKey(nil)
-	if err != nil {
-		fmt.Printf("failed to generate key: %s\n", err)
-		return
-	}
-
-	// Sign and verify with raw keys
-	signed, err := jws.Sign([]byte("hello"), jws.WithKey(jwa.EdDSAEd448(), priv))
-	if err != nil {
-		fmt.Printf("failed to sign: %s\n", err)
-		return
-	}
-
-	payload, err := jws.Verify(signed, jws.WithKey(jwa.EdDSAEd448(), pub))
-	if err != nil {
-		fmt.Printf("failed to verify: %s\n", err)
-		return
-	}
-	fmt.Printf("%s\n", payload)
-
-	// Import into JWK
-	jwkKey, err := jwk.Import(priv)
-	if err != nil {
-		fmt.Printf("failed to import key: %s\n", err)
-		return
-	}
-	_ = jwkKey
-}
 ```
+<!-- END INCLUDE -->
 
 # What gets registered
 

example_test.go

@@ -0,0 +1,83 @@
+package ed448_test
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/cloudflare/circl/sign/ed448"
+	"github.com/lestrrat-go/jwx/v3/jwa"
+	"github.com/lestrrat-go/jwx/v3/jwk"
+	"github.com/lestrrat-go/jwx/v3/jws"
+
+	_ "github.com/lestrrat-go/jwx-circl-ed448"
+)
+
+func Example() {
+	// Generate an Ed448 key pair
+	pub, priv, err := ed448.GenerateKey(nil)
+	if err != nil {
+		fmt.Printf("failed to generate key: %s\n", err)
+		return
+	}
+
+	payload := []byte("Hello, Ed448!")
+
+	// Sign and verify with raw keys
+	signed, err := jws.Sign(payload, jws.WithKey(jwa.EdDSAEd448(), priv))
+	if err != nil {
+		fmt.Printf("failed to sign: %s\n", err)
+		return
+	}
+
+	verified, err := jws.Verify(signed, jws.WithKey(jwa.EdDSAEd448(), pub))
+	if err != nil {
+		fmt.Printf("failed to verify: %s\n", err)
+		return
+	}
+	fmt.Printf("%s\n", verified)
+
+	// Import raw keys into JWK
+	jwkPriv, err := jwk.Import(priv)
+	if err != nil {
+		fmt.Printf("failed to import private key: %s\n", err)
+		return
+	}
+
+	jwkPub, err := jwk.Import(pub)
+	if err != nil {
+		fmt.Printf("failed to import public key: %s\n", err)
+		return
+	}
+
+	// Sign and verify with JWK keys
+	signed, err = jws.Sign(payload, jws.WithKey(jwa.EdDSAEd448(), jwkPriv))
+	if err != nil {
+		fmt.Printf("failed to sign with JWK key: %s\n", err)
+		return
+	}
+
+	verified, err = jws.Verify(signed, jws.WithKey(jwa.EdDSAEd448(), jwkPub))
+	if err != nil {
+		fmt.Printf("failed to verify with JWK key: %s\n", err)
+		return
+	}
+	fmt.Printf("%s\n", verified)
+
+	// JWK JSON round-trip
+	buf, err := json.MarshalIndent(jwkPriv, "", "  ")
+	if err != nil {
+		fmt.Printf("failed to marshal JWK: %s\n", err)
+		return
+	}
+
+	parsed, err := jwk.ParseKey(buf)
+	if err != nil {
+		fmt.Printf("failed to parse JWK: %s\n", err)
+		return
+	}
+	_ = parsed
+
+	// Output:
+	// Hello, Ed448!
+	// Hello, Ed448!
+}