func (m *MockCryptoSuite) Sign(k apicryptosuite.Key, digest []byte,
	opts apicryptosuite.SignerOpts) (signature []byte, err error) {
	return []byte("testSignature"), nil
}
Sign mock signing
package mocks
import (
	"hash"
	"github.com/hyperledger/fabric-sdk-go/api/apicryptosuite"
)
type MockCryptoSuite struct {
}
func (m *MockCryptoSuite) KeyGen(opts apicryptosuite.KeyGenOpts) (k apicryptosuite.Key, err error) {
	return nil, nil
}
func (m *MockCryptoSuite) KeyImport(raw interface{},
	opts apicryptosuite.KeyImportOpts) (k apicryptosuite.Key, err error) {
	return nil, nil
}
func (m *MockCryptoSuite) GetKey(ski []byte) (k apicryptosuite.Key, err error) {
	return nil, nil
}
func (m *MockCryptoSuite) Hash(msg []byte, opts apicryptosuite.HashOpts) (hash []byte, err error) {
	return nil, nil
}
func (m *MockCryptoSuite) GetHash(opts apicryptosuite.HashOpts) (h hash.Hash, err error) {
	return nil, nil
}