blockdb: allow to dump blocks to json-encoded file

- Allow to dump blockdb to a json file
  - Compared to leveldb, a json file is easier to trace.
- Add interfaces block database:
  - Close would be required by database that needs cleanup.
  - BlockIterator is required when we need to access 'all' blocks,
     adding a new method 'GetAll' as the constructor for iterators.
- Remove GetByValidatorAndHeight from blockdb.Reader
  - This function is not used anywhere, to make interface
     minimum, remove it.
- Fix typo: backend -> backed

1 files changed, 3 insertions, 1 deletions

diff --git a/core/blocklattice_test.go b/core/blocklattice_test.go
index 3dd5a3b..0f78dc5 100644
--- a/core/blocklattice_test.go
+++ b/core/blocklattice_test.go
@@ -68,7 +68,9 @@ func (s *BlockLatticeTest) SetupTest() {
 
 	s.app = &TestApp{}
 
-	lattice = NewBlockLattice(blockdb.NewMemBackedBlockDB(), s.app)
+	db, err := blockdb.NewMemBackedBlockDB()
+	s.Require().Nil(err)
+	lattice = NewBlockLattice(db, s.app)
 
 	for i := 0; i < 4; i++ {
 		validators = append(validators,