[FAB-1771] Add chain config mock structure

https://jira.hyperledger.org/browse/FAB-1771

This changeset adds a mock structure for the chainconfig.Descriptor.  It
also fixes a bug in the chainconfig.DescriptorImpl as it did not
actually implement the interface.

Change-Id: Iab2041dc07c6fc19b586485608068f417619cd16
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

common/chainconfig/chainconfig.go

@@ -57,7 +57,7 @@ type Descriptor interface {
 
 	// BlockDataHashingStructureWidth returns the width to use when constructing the
 	// Merkle tree to compute the BlockData hash
-	BlockDatahashingStructureWidth() int
+	BlockDataHashingStructureWidth() uint32
 
 	// OrdererAddresses returns the list of valid orderer addresses to connect to to invoke Broadcast/Deliver
 	OrdererAddresses() []string

common/chainconfig/chainconfig_test.go

@@ -37,6 +37,10 @@ func makeInvalidConfigItem(key string) *cb.ConfigurationItem {
 	}
 }
 
+func TestInterface(t *testing.T) {
+	_ = Descriptor(NewDescriptorImpl())
+}
+
 func TestDoubleBegin(t *testing.T) {
 	defer func() {
 		if err := recover(); err == nil {

common/mocks/chainconfig/chainconfig.go

@@ -0,0 +1,48 @@
+/*
+Copyright IBM Corp. 2016 All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+                 http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package chainconfig
+
+import "github.com/hyperledger/fabric/common/util"
+
+func nearIdentityHash(input []byte) []byte {
+	return util.ConcatenateBytes([]byte("Hash("), input, []byte(""))
+}
+
+// Descriptor is a mock implementation of sharedconfig.Descriptor
+type Descriptor struct {
+	// HashingAlgorithmVal is returned as the result of HashingAlgorithm()
+	HashingAlgorithmVal func([]byte) []byte
+	// BlockDataHashingStructureWidthVal is returned as the result of BlockDataHashingStructureWidth()
+	BlockDataHashingStructureWidthVal uint32
+	// OrdererAddressesVal is returned as the result of OrdererAddresses()
+	OrdererAddressesVal []string
+}
+
+// HashingAlgorithm returns the HashingAlgorithmVal
+func (scm *Descriptor) HashingAlgorithm() func([]byte) []byte {
+	return scm.HashingAlgorithmVal
+}
+
+// BlockDataHashingStructureWidth returns the BlockDataHashingStructureWidthVal
+func (scm *Descriptor) BlockDataHashingStructureWidth() uint32 {
+	return scm.BlockDataHashingStructureWidthVal
+}
+
+// OrdererAddresses returns the OrdererAddressesVal
+func (scm *Descriptor) OrdererAddresses() []string {
+	return scm.OrdererAddressesVal
+}

common/mocks/chainconfig/chainconfig_test.go

@@ -0,0 +1,27 @@
+/*
+Copyright IBM Corp. 2016 All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+                 http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package chainconfig
+
+import (
+	"testing"
+
+	"github.com/hyperledger/fabric/common/chainconfig"
+)
+
+func TestChainConfigInterface(t *testing.T) {
+	_ = chainconfig.Descriptor(&Descriptor{})
+}