fix chain head

commands/chain.go

@@ -29,11 +29,20 @@ var chainHeadCmd = &cmds.Command{
 		Tagline: "Get heaviest tipset CIDs",
 	},
 	Run: func(req *cmds.Request, re cmds.ResponseEmitter, env cmds.Environment) error {
-		headTipset := GetPorcelainAPI(env).ChainHead(req.Context)
-		blocks := headTipset.ToSlice()
-		return re.Emit(blocks)
+		return re.Emit(GetPorcelainAPI(env).ChainHead(req.Context).ToSortedCidSet())
 	},
 	Type: []cid.Cid{},
+	Encoders: cmds.EncoderMap{
+		cmds.Text: cmds.MakeTypedEncoder(func(req *cmds.Request, w io.Writer, res []cid.Cid) error {
+			for _, r := range res {
+				_, err := fmt.Fprintln(w, r.String())
+				if err != nil {
+					return err
+				}
+			}
+			return nil
+		}),
+	},
 }
 
 var chainLsCmd = &cmds.Command{

commands/chain_daemon_test.go

@@ -16,6 +16,23 @@ import (
 	"gx/ipfs/QmPVkJMTeRC6iBByPWdrRkD3BE5UXsj5HPzb4kPqL186mS/testify/require"
 )
 
+func TestChainHead(t *testing.T) {
+	t.Parallel()
+	require := require.New(t)
+	assert := assert.New(t)
+
+	d := th.NewDaemon(t).Start()
+	defer d.ShutdownSuccess()
+
+	op := d.RunSuccess("chain", "head")
+	result := op.ReadStdoutTrimNewlines()
+
+	maybeCid, err := cid.Decode(result)
+	require.NoError(err)
+
+	assert.Equal(result, maybeCid.String())
+}
+
 func TestChainDaemon(t *testing.T) {
 	t.Parallel()
 	t.Run("chain ls with json encoding returns the whole chain as json", func(t *testing.T) {