Merge pull request #3971 from filecoin-project/init-remove

add init.State#Remove() for testing.

chain/actors/builtin/init/init.go

@@ -36,4 +36,9 @@ type State interface {
 	NetworkName() (dtypes.NetworkName, error)
 
 	ForEachActor(func(id abi.ActorID, address address.Address) error) error
+
+	// Remove exists to support tooling that manipulates state for testing.
+	// It should not be used in production code, as init actor entries are
+	// immutable.
+	Remove(addrs ...address.Address) error
 }

chain/actors/builtin/init/v0.go

@@ -4,6 +4,7 @@ import (
 	"github.com/filecoin-project/go-address"
 	"github.com/filecoin-project/go-state-types/abi"
 	cbg "github.com/whyrusleeping/cbor-gen"
+	"golang.org/x/xerrors"
 
 	init_ "github.com/filecoin-project/specs-actors/actors/builtin/init"
 
@@ -46,3 +47,21 @@ func (s *state0) ForEachActor(cb func(id abi.ActorID, address address.Address) e
 func (s *state0) NetworkName() (dtypes.NetworkName, error) {
 	return dtypes.NetworkName(s.State.NetworkName), nil
 }
+
+func (s *state0) Remove(addrs ...address.Address) (err error) {
+	m, err := adt0.AsMap(s.store, s.State.AddressMap)
+	if err != nil {
+		return err
+	}
+	for _, addr := range addrs {
+		if err = m.Delete(abi.AddrKey(addr)); err != nil {
+			return xerrors.Errorf("failed to delete entry for address: %s; err: %w", addr, err)
+		}
+	}
+	amr, err := m.Root()
+	if err != nil {
+		return xerrors.Errorf("failed to get address map root: %w", err)
+	}
+	s.State.AddressMap = amr
+	return nil
+}