Add the RPop command

wredis_lists.go

@@ -23,3 +23,14 @@ func (w *Wredis) LPush(key string, items ...string) (int64, error) {
 		return redis.Int64(conn.Do("LPUSH", args...))
 	})
 }
+
+// RPop removes and returns the last element of the list stored at key. For more
+// information, see http://redis.io/commands/rpop.
+func (w *Wredis) RPop(key string) (string, error) {
+	if key == "" {
+		return stringError("key cannot be empty")
+	}
+	return w.ExecString(func(conn redis.Conn) (string, error) {
+		return redis.String(conn.Do("RPOP", key))
+	})
+}

wredis_lists_test.go

@@ -48,4 +48,32 @@ var _ = Describe("WredisLists", func() {
 			Ω(n).Should(Equal(int64(4)))
 		})
 	})
+
+	Context("RPop", func() {
+		BeforeEach(func() {
+			unsafe.Del(testList)
+		})
+
+		It("should return an error when no key provided", func() {
+			_, err := safe.RPop("")
+			Ω(err).Should(HaveOccurred())
+			Ω(err.Error()).Should(Equal("key cannot be empty"))
+		})
+
+		It("should return an error when popping from an empty list", func() {
+			_, err := safe.RPop(testList)
+			Ω(err).Should(HaveOccurred())
+			Ω(err.Error()).Should(Equal("redigo: nil returned"))
+		})
+
+		It("should return the last item in a list", func() {
+			n, err := safe.LPush(testList, "1", "2", "3")
+			Ω(err).ShouldNot(HaveOccurred())
+			Ω(n).Should(Equal(int64(n)))
+
+			i, err := safe.RPop(testList)
+			Ω(err).ShouldNot(HaveOccurred())
+			Ω(i).Should(Equal("1"))
+		})
+	})
 })