use pre-parsed rsa key for rsa benchmark and make sure signing actually succeeds

jwt_test.go

@@ -178,7 +178,9 @@ func benchmarkSigning(b *testing.B, method jwt.SigningMethod, key interface{}) {
 	t := jwt.New(method)
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
-			t.SignedString(key)
+			if _, err := t.SignedString(key); err != nil {
+				b.Fatal(err)
+			}
 		}
 	})
 

rsa_test.go

@@ -144,13 +144,31 @@ func TestRSAKeyParsing(t *testing.T) {
 }
 
 func BenchmarkRS256Signing(b *testing.B) {
-	benchmarkSigning(b, jwt.SigningMethodRS256, hmacTestKey)
+	key, _ := ioutil.ReadFile("test/sample_key")
+	parsedKey, err := jwt.ParseRSAPrivateKeyFromPEM(key)
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	benchmarkSigning(b, jwt.SigningMethodRS256, parsedKey)
 }
 
 func BenchmarkRS384Signing(b *testing.B) {
-	benchmarkSigning(b, jwt.SigningMethodRS384, hmacTestKey)
+	key, _ := ioutil.ReadFile("test/sample_key")
+	parsedKey, err := jwt.ParseRSAPrivateKeyFromPEM(key)
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	benchmarkSigning(b, jwt.SigningMethodRS384, parsedKey)
 }
 
 func BenchmarkRS512Signing(b *testing.B) {
-	benchmarkSigning(b, jwt.SigningMethodRS512, hmacTestKey)
+	key, _ := ioutil.ReadFile("test/sample_key")
+	parsedKey, err := jwt.ParseRSAPrivateKeyFromPEM(key)
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	benchmarkSigning(b, jwt.SigningMethodRS512, parsedKey)
 }