separate mock evidence from real evidence (#2571)

Closes #2525

evidence/pool_test.go

@@ -1,6 +1,7 @@
 package evidence
 
 import (
+	"os"
 	"sync"
 	"testing"
 
@@ -14,6 +15,13 @@ import (
 
 var mockState = sm.State{}
 
+func TestMain(m *testing.M) {
+	types.RegisterMockEvidences(cdc)
+
+	code := m.Run()
+	os.Exit(code)
+}
+
 func initializeValidatorState(valAddr []byte, height int64) dbm.DB {
 	stateDB := dbm.NewMemDB()