no empty blocks

types/services.go

@@ -23,6 +23,8 @@ type Mempool interface {
 	Reap(int) Txs
 	Update(height int, txs Txs)
 	Flush()
+
+	TxsAvailable() chan struct{}
 }
 
 type MockMempool struct {
@@ -35,6 +37,7 @@ func (m MockMempool) CheckTx(tx Tx, cb func(*abci.Response)) error { return nil
 func (m MockMempool) Reap(n int) Txs                               { return Txs{} }
 func (m MockMempool) Update(height int, txs Txs)                   {}
 func (m MockMempool) Flush()                                       {}
+func (m MockMempool) TxsAvailable() chan struct{}                  { return make(chan struct{}) }
 
 //------------------------------------------------------
 // blockstore