Handle -1 in DurationCmd

Makefile

@@ -1,7 +1,7 @@
 all: testdeps
 	go test ./...
 	go test ./... -short -race
-	go test ./... -run=NONE -bench=.
+	go test ./... -run=NONE -bench=. -benchmem
 	env GOOS=linux GOARCH=386 go test ./...
 	go vet
 	go get github.com/gordonklaus/ineffassign

command.go

@@ -439,7 +439,14 @@ func (cmd *DurationCmd) readReply(rd *proto.Reader) error {
 	if cmd.err != nil {
 		return cmd.err
 	}
-	cmd.val = time.Duration(n) * cmd.precision
+	switch n {
+	// -2 if the key does not exist
+	// -1 if the key exists but has no associated expire
+	case -2, -1:
+		cmd.val = time.Duration(n)
+	default:
+		cmd.val = time.Duration(n) * cmd.precision
+	}
 	return nil
 }
 

commands_test.go

@@ -374,7 +374,11 @@ var _ = Describe("Commands", func() {
 
 			ttl = client.TTL("key")
 			Expect(ttl.Err()).NotTo(HaveOccurred())
-			Expect(ttl.Val() < 0).To(Equal(true))
+			Expect(ttl.Val()).To(Equal(time.Duration(-1)))
+
+			ttl = client.TTL("nonexistent_key")
+			Expect(ttl.Err()).NotTo(HaveOccurred())
+			Expect(ttl.Val()).To(Equal(time.Duration(-2)))
 		})
 
 		It("should ExpireAt", func() {