Expose a query endpoint for latest published valset (#985)

* Expose a query endpoint for latest published valset

Pigeon currently gets this information by querying the compass contract.
The problem is, when there is a just-in-time valset update, pigeon will
end up using an old valset because the new valset hasn't been committed
yet.  We need the newest valset that may still be pending on the evm
chain.

Now, we can query paloma instead of the evm contract.  Paloma knows what
the latest published valset is, even if it hasn't yet been committed.

* Add tests

---------

Co-authored-by: Tyler Ruppert <{ID}+{username}@users.noreply.github.com>

proto/palomachain/paloma/valset/query.proto

@@ -30,6 +30,10 @@ service Query {
         "/palomachain/paloma/valset/get_snapshot_by_id/{snapshotId}";
   }
 
+  // Queries the most recent published snapshot for a chain.
+  rpc GetLatestPublishedSnapshot(QueryGetLatestPublishedSnapshotRequest)
+      returns (QueryGetLatestPublishedSnapshotResponse) {}
+
   // Queries a list of GetValidatorAliveUntil items.
   rpc GetValidatorAliveUntil(QueryGetValidatorAliveUntilRequest)
       returns (QueryGetValidatorAliveUntilResponse) {
@@ -77,6 +81,14 @@ message QueryGetSnapshotByIDResponse {
   Snapshot snapshot = 1;
 }
 
+message QueryGetLatestPublishedSnapshotRequest {
+  string chainReferenceID = 1;
+}
+
+message QueryGetLatestPublishedSnapshotResponse {
+  Snapshot snapshot = 1;
+}
+
 message QueryGetValidatorAliveUntilRequest {
   bytes valAddress = 1
       [(gogoproto.casttype) = "github.com/cosmos/cosmos-sdk/types.ValAddress"];

x/valset/client/cli/query.go

@@ -23,6 +23,7 @@ func GetQueryCmd(queryRoute string) *cobra.Command {
 	cmd.AddCommand(CmdValidatorInfo())
 
 	cmd.AddCommand(CmdGetSnapshotByID())
+	cmd.AddCommand(CmdGetLatestPublishedSnapshot())
 
 	cmd.AddCommand(CmdGetValidatorAliveUntil())
 

x/valset/client/cli/query_get_latest_published_snapshot.go

@@ -0,0 +1,39 @@
+package cli
+
+import (
+	"github.com/cosmos/cosmos-sdk/client"
+	"github.com/cosmos/cosmos-sdk/client/flags"
+	"github.com/palomachain/paloma/x/valset/types"
+	"github.com/spf13/cobra"
+)
+
+func CmdGetLatestPublishedSnapshot() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "get-latest-published-snapshot [chain-reference-id]",
+		Short: "Query GetLatestPublishedSnapshot",
+		Args:  cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) (err error) {
+			clientCtx, err := client.GetClientTxContext(cmd)
+			if err != nil {
+				return err
+			}
+
+			queryClient := types.NewQueryClient(clientCtx)
+
+			params := &types.QueryGetLatestPublishedSnapshotRequest{
+				ChainReferenceID: args[0],
+			}
+
+			res, err := queryClient.GetLatestPublishedSnapshot(cmd.Context(), params)
+			if err != nil {
+				return err
+			}
+
+			return clientCtx.PrintProto(res)
+		},
+	}
+
+	flags.AddQueryFlagsToCmd(cmd)
+
+	return cmd
+}

x/valset/keeper/grpc_query_get_latest_published_snapshot.go

@@ -0,0 +1,26 @@
+package keeper
+
+import (
+	"context"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/palomachain/paloma/x/valset/types"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func (k Keeper) GetLatestPublishedSnapshot(goCtx context.Context, req *types.QueryGetLatestPublishedSnapshotRequest) (*types.QueryGetLatestPublishedSnapshotResponse, error) {
+	if req == nil {
+		return nil, status.Error(codes.InvalidArgument, "invalid request")
+	}
+
+	ctx := sdk.UnwrapSDKContext(goCtx)
+	snapshot, err := k.GetLatestSnapshotOnChain(ctx, req.ChainReferenceID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &types.QueryGetLatestPublishedSnapshotResponse{
+		Snapshot: snapshot,
+	}, nil
+}

x/valset/keeper/grpc_query_get_latest_published_snapshot_test.go

@@ -0,0 +1,72 @@
+package keeper
+
+import (
+	"testing"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	keeperutil "github.com/palomachain/paloma/util/keeper"
+	"github.com/palomachain/paloma/x/valset/types"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetLatestPublishedSnapshot(t *testing.T) {
+	testcases := []struct {
+		name          string
+		setup         func(sdk.Context, *Keeper, mockedServices) *types.QueryGetLatestPublishedSnapshotResponse
+		request       *types.QueryGetLatestPublishedSnapshotRequest
+		expectedError error
+	}{
+		{
+			name: "returns the latest published snapshot",
+			setup: func(ctx sdk.Context, k *Keeper, ms mockedServices) *types.QueryGetLatestPublishedSnapshotResponse {
+				ms.StakingKeeper.On("IterateValidators", mock.Anything, mock.Anything).Return(nil)
+
+				snapshot, err := k.createNewSnapshot(ctx)
+				require.NoError(t, err)
+
+				err = k.setSnapshotAsCurrent(ctx, snapshot)
+				require.NoError(t, err)
+
+				snapshot, err = k.GetCurrentSnapshot(ctx)
+				require.NoError(t, err)
+
+				k.SetSnapshotOnChain(ctx, snapshot.Id, "test-chain")
+
+				snapshot, err = k.GetCurrentSnapshot(ctx)
+				require.NoError(t, err)
+
+				return &types.QueryGetLatestPublishedSnapshotResponse{
+					Snapshot: snapshot,
+				}
+			},
+			request: &types.QueryGetLatestPublishedSnapshotRequest{
+				ChainReferenceID: "test-chain",
+			},
+		},
+		{
+			name: "returns error when no snapshot published",
+			setup: func(ctx sdk.Context, k *Keeper, ms mockedServices) *types.QueryGetLatestPublishedSnapshotResponse {
+				return nil
+			},
+			request: &types.QueryGetLatestPublishedSnapshotRequest{
+				ChainReferenceID: "test-chain",
+			},
+			expectedError: keeperutil.ErrNotFound.Format(&types.Snapshot{}, []byte{0, 0, 0, 0, 0, 0, 0, 0}),
+		},
+	}
+
+	asserter := assert.New(t)
+	for _, tt := range testcases {
+		t.Run(tt.name, func(t *testing.T) {
+			k, ms, ctx := newValsetKeeper(t)
+
+			expected := tt.setup(ctx, k, ms)
+
+			actual, actualErr := k.GetLatestPublishedSnapshot(ctx, tt.request)
+			asserter.Equal(expected, actual)
+			asserter.Equal(tt.expectedError, actualErr)
+		})
+	}
+}