[FAB-12545] Fix mock stub PutState on empty value

The chaincode shim mock stub should delete the state key if the
value supplied to PutState is empty. Currently, it stores the key
with an empty value.

Change-Id: Ib5fe46b84ed4ad8befac94491515d3dd55a94d2d
Signed-off-by: Sheehan Anderson <sranderson@gmail.com>

core/chaincode/shim/mockstub.go

@@ -211,6 +211,12 @@ func (stub *MockStub) PutState(key string, value []byte) error {
 		return err
 	}
 
+	// If the value is nil or empty, delete the key
+	if len(value) == 0 {
+		mockLogger.Debug("MockStub", stub.Name, "PutState called, but value is nil or empty. Delete ", key)
+		return stub.DelState(key)
+	}
+
 	mockLogger.Debug("MockStub", stub.Name, "Putting", key, value)
 	stub.State[key] = value
 

core/chaincode/shim/mockstub_test.go

@@ -24,6 +24,7 @@ import (
 
 	"github.com/hyperledger/fabric/common/flogging"
 	"github.com/spf13/viper"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestMockStateRangeQueryIterator(t *testing.T) {
@@ -235,6 +236,64 @@ func TestGetTxTimestamp(t *testing.T) {
 	stub.MockTransactionEnd("init")
 }
 
+// TestPutEmptyState confirms that setting a key value to empty or nil in the mock state deletes the key
+// instead of storing an empty key.
+func TestPutEmptyState(t *testing.T) {
+	stub := NewMockStub("FAB-12545", nil)
+
+	// Put an empty and nil state value
+	stub.MockTransactionStart("1")
+	err := stub.PutState("empty", []byte{})
+	assert.NoError(t, err)
+	err = stub.PutState("nil", nil)
+	assert.NoError(t, err)
+	stub.MockTransactionEnd("1")
+
+	// Confirm both are nil
+	stub.MockTransactionStart("2")
+	val, err := stub.GetState("empty")
+	assert.NoError(t, err)
+	assert.Nil(t, val)
+	val, err = stub.GetState("nil")
+	assert.NoError(t, err)
+	assert.Nil(t, val)
+	// Add a value to both empty and nil
+	err = stub.PutState("empty", []byte{0})
+	assert.NoError(t, err)
+	err = stub.PutState("nil", []byte{0})
+	assert.NoError(t, err)
+	stub.MockTransactionEnd("2")
+
+	// Confirm the value is in both
+	stub.MockTransactionStart("3")
+	val, err = stub.GetState("empty")
+	assert.NoError(t, err)
+	assert.Equal(t, val, []byte{0})
+	val, err = stub.GetState("nil")
+	assert.NoError(t, err)
+	assert.Equal(t, val, []byte{0})
+	stub.MockTransactionEnd("3")
+
+	// Set both back to empty / nil
+	stub.MockTransactionStart("4")
+	err = stub.PutState("empty", []byte{})
+	assert.NoError(t, err)
+	err = stub.PutState("nil", nil)
+	assert.NoError(t, err)
+	stub.MockTransactionEnd("4")
+
+	// Confirm both are nil
+	stub.MockTransactionStart("5")
+	val, err = stub.GetState("empty")
+	assert.NoError(t, err)
+	assert.Nil(t, val)
+	val, err = stub.GetState("nil")
+	assert.NoError(t, err)
+	assert.Nil(t, val)
+	stub.MockTransactionEnd("5")
+
+}
+
 //TestMockMock clearly cheating for coverage... but not. Mock should
 //be tucked away under common/mocks package which is not
 //included for coverage. Moving mockstub to another package