feat(dot/rpc) Add system_localPeerId rpc call (ChainSafe#1690)

* chore: add local peer id rpc call

* chore: add func desc

* cover empty test case

* chore: ignore Id on func name

* chore: adjusts tests

dot/rpc/modules/system.go

@@ -25,6 +25,7 @@ import (
 	"github.com/ChainSafe/gossamer/lib/common"
 	"github.com/ChainSafe/gossamer/lib/crypto"
 	"github.com/ChainSafe/gossamer/pkg/scale"
+	"github.com/btcsuite/btcutil/base58"
 	ctypes "github.com/centrifuge/go-substrate-rpc-client/v3/types"
 )
 
@@ -226,3 +227,14 @@ func (sm *SystemModule) AccountNextIndex(r *http.Request, req *StringRequest, re
 	*res = U64Response(accountInfo.Nonce)
 	return nil
 }
+
+// LocalPeerId Returns the base58-encoded PeerId fo the node.
+func (sm *SystemModule) LocalPeerId(r *http.Request, req *EmptyRequest, res *string) error { //nolint
+	netstate := sm.networkAPI.NetworkState()
+	if netstate.PeerID == "" {
+		return errors.New("peer id cannot be empty")
+	}
+
+	*res = base58.Encode([]byte(netstate.PeerID))
+	return nil
+}

dot/rpc/modules/system_test.go

@@ -26,6 +26,7 @@ import (
 
 	"github.com/ChainSafe/gossamer/dot/core"
 	"github.com/ChainSafe/gossamer/dot/network"
+	"github.com/ChainSafe/gossamer/dot/rpc/modules/mocks"
 	"github.com/ChainSafe/gossamer/dot/state"
 	"github.com/ChainSafe/gossamer/dot/types"
 	"github.com/ChainSafe/gossamer/lib/common"
@@ -37,6 +38,7 @@ import (
 	"github.com/ChainSafe/gossamer/lib/trie"
 	"github.com/ChainSafe/gossamer/pkg/scale"
 	log "github.com/ChainSafe/log15"
+	"github.com/btcsuite/btcutil/base58"
 	"github.com/stretchr/testify/require"
 )
 
@@ -371,3 +373,29 @@ func newCoreService(t *testing.T, srvc *state.Service) *core.Service {
 
 	return core.NewTestService(t, cfg)
 }
+
+func TestLocalPeerId(t *testing.T) {
+	peerID := "12D3KooWBrwpqLE9Z23NEs59m2UHUs9sGYWenxjeCk489Xq7SG2h"
+	encoded := base58.Encode([]byte(peerID))
+
+	state := common.NetworkState{
+		PeerID: peerID,
+	}
+
+	mocknetAPI := new(mocks.MockNetworkAPI)
+	mocknetAPI.On("NetworkState").Return(state).Once()
+
+	sysmodules := new(SystemModule)
+	sysmodules.networkAPI = mocknetAPI
+
+	var res string
+	err := sysmodules.LocalPeerId(nil, nil, &res)
+	require.NoError(t, err)
+
+	require.Equal(t, res, encoded)
+
+	state.PeerID = ""
+	mocknetAPI.On("NetworkState").Return(state).Once()
+	err = sysmodules.LocalPeerId(nil, nil, &res)
+	require.Error(t, err)
+}

dot/rpc/service_test.go

@@ -33,7 +33,7 @@ func TestNewService(t *testing.T) {
 }
 
 func TestService_Methods(t *testing.T) {
-	qtySystemMethods := 10
+	qtySystemMethods := 11
 	qtyRPCMethods := 1
 	qtyAuthorMethods := 7