command: string - strlen

internal/command/command.go

@@ -126,6 +126,8 @@ func Parse(args [][]byte) (redis.Cmd, error) {
 		return str.ParseSetEX(b, 1000)
 	case "setnx":
 		return str.ParseSetNX(b)
+	case "strlen":
+		return str.ParseStrlen(b)
 
 	// hash
 	case "hdel":

internal/command/string/strlen.go

@@ -0,0 +1,37 @@
+package string
+
+import (
+	"github.com/nalgeon/redka/internal/core"
+	"github.com/nalgeon/redka/internal/redis"
+)
+
+// Strlen returns the length of a string value.
+// STRLEN key
+// https://redis.io/commands/strlen
+type Strlen struct {
+	redis.BaseCmd
+	key string
+}
+
+func ParseStrlen(b redis.BaseCmd) (Strlen, error) {
+	cmd := Strlen{BaseCmd: b}
+	if len(cmd.Args()) != 1 {
+		return Strlen{}, redis.ErrInvalidArgNum
+	}
+	cmd.key = string(cmd.Args()[0])
+	return cmd, nil
+}
+
+func (cmd Strlen) Run(w redis.Writer, red redis.Redka) (any, error) {
+	val, err := red.Str().Get(cmd.key)
+	if err == core.ErrNotFound {
+		w.WriteInt(0)
+		return 0, nil
+	}
+	if err != nil {
+		w.WriteError(cmd.Error(err))
+		return nil, err
+	}
+	w.WriteInt(len(val))
+	return len(val), nil
+}

internal/command/string/strlen_test.go

@@ -0,0 +1,71 @@
+package string
+
+import (
+	"testing"
+
+	"github.com/nalgeon/redka/internal/redis"
+	"github.com/nalgeon/redka/internal/testx"
+)
+
+func TestStrlenParse(t *testing.T) {
+	tests := []struct {
+		cmd  string
+		want Strlen
+		err  error
+	}{
+		{
+			cmd:  "strlen",
+			want: Strlen{},
+			err:  redis.ErrInvalidArgNum,
+		},
+		{
+			cmd:  "strlen name",
+			want: Strlen{key: "name"},
+			err:  nil,
+		},
+		{
+			cmd:  "strlen name age",
+			want: Strlen{},
+			err:  redis.ErrInvalidArgNum,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.cmd, func(t *testing.T) {
+			cmd, err := redis.Parse(ParseStrlen, test.cmd)
+			testx.AssertEqual(t, err, test.err)
+			if err == nil {
+				testx.AssertEqual(t, cmd.key, test.want.key)
+			} else {
+				testx.AssertEqual(t, cmd, test.want)
+			}
+		})
+	}
+}
+
+func TestStrlenExec(t *testing.T) {
+	t.Run("strlen", func(t *testing.T) {
+		db, red := getDB(t)
+		defer db.Close()
+		_ = db.Str().Set("name", "alice")
+
+		cmd := redis.MustParse(ParseStrlen, "strlen name")
+		conn := redis.NewFakeConn()
+		res, err := cmd.Run(conn, red)
+		testx.AssertNoErr(t, err)
+		testx.AssertEqual(t, res, 5)
+		testx.AssertEqual(t, conn.Out(), "5")
+	})
+
+	t.Run("key not found", func(t *testing.T) {
+		db, red := getDB(t)
+		defer db.Close()
+
+		cmd := redis.MustParse(ParseStrlen, "strlen name")
+		conn := redis.NewFakeConn()
+		res, err := cmd.Run(conn, red)
+		testx.AssertNoErr(t, err)
+		testx.AssertEqual(t, res, 0)
+		testx.AssertEqual(t, conn.Out(), "0")
+	})
+}