func TestDuplicateExtensionsCSR(t *testing.T) {
	b, _ := pem.Decode([]byte(dupExtCSR))
	if b == nil {
		t.Fatalf("couldn't decode test CSR")
	}
	_, err := ParseCertificateRequest(b.Bytes)
	if err == nil {
		t.Fatal("ParseCertificateRequest should fail when parsing CSR with duplicate extensions")
	}
}

const dupAttCSR = `-----BEGIN CERTIFICATE REQUEST-----

pkg crypto/tls, type ConnectionState struct, Version uint16
pkg crypto/tls, type CurveID uint16
pkg crypto/x509, func CreateCertificateRequest(io.Reader, *CertificateRequest, interface{}) ([]uint8, error)
pkg crypto/x509, func ParseCertificateRequest([]uint8) (*CertificateRequest, error)
pkg crypto/x509, type CertificateRequest struct
pkg crypto/x509, type CertificateRequest struct, Attributes []pkix.AttributeTypeAndValueSET