fix: keyPrefix should work with Buffer

Closes #1486

Author: luin

Diff for: lib/Command.ts

@@ -181,7 +181,24 @@ export default class Command implements Respondable {
     this.initPromise();
 
     if (options.keyPrefix) {
-      this._iterateKeys((key) => options.keyPrefix + key);
+      // @ts-expect-error
+      const isBufferKeyPrefix = options.keyPrefix instanceof Buffer;
+      // @ts-expect-error
+      let keyPrefixBuffer: Buffer | null = isBufferKeyPrefix
+        ? options.keyPrefix
+        : null;
+      this._iterateKeys((key) => {
+        if (key instanceof Buffer) {
+          if (keyPrefixBuffer === null) {
+            keyPrefixBuffer = Buffer.from(options.keyPrefix);
+          }
+          return Buffer.concat([keyPrefixBuffer, key]);
+        } else if (isBufferKeyPrefix) {
+          // @ts-expect-error
+          return Buffer.concat([options.keyPrefix, Buffer.from(String(key))]);
+        }
+        return options.keyPrefix + key;
+      });
     }
 
     if (options.readOnly) {
@@ -327,8 +344,8 @@ export default class Command implements Respondable {
    * Iterate through the command arguments that are considered keys.
    */
   private _iterateKeys(
-    transform: Function = (key) => key
-  ): Array<string | Buffer> {
+    transform: (key: CommandParameter) => CommandParameter = (key) => key
+  ): (string | Buffer)[] {
     if (typeof this.keys === "undefined") {
       this.keys = [];
       if (exists(this.name)) {

Diff for: test/functional/cluster/scripting.ts

@@ -12,7 +12,6 @@ describe("cluster:scripting", () => {
           [12182, 16383, ["127.0.0.1", 30002]],
         ];
       }
-      console.log(argv);
       if (argv[0] === "eval" && argv[1] === lua && argv[2] === "2") {
         return argv.slice(3);
       }

Diff for: test/functional/send_command.ts

@@ -59,6 +59,7 @@ describe("send command", () => {
         expect(res).to.eql("OK");
       }
     );
+    // @ts-expect-error
     redis.callBuffer("get", Buffer.from("foo"), function (err, result) {
       expect(result).to.be.instanceof(Buffer);
       expect(result.toString()).to.eql("bar");
@@ -149,6 +150,40 @@ describe("send command", () => {
     });
   });
 
+  it("should support prefixing buffer keys", async () => {
+    const redis = new Redis({ keyPrefix: "foo:" });
+    await redis.mset(
+      Buffer.from("bar"),
+      Buffer.from("baz"),
+      Buffer.from("foo"),
+      Buffer.from("baz")
+    );
+    await redis.set(Buffer.from([0xff]), Buffer.from("baz"));
+
+    const redisWOPrefix = new Redis();
+    expect(await redisWOPrefix.get("foo:bar")).to.eql("baz");
+    expect(await redisWOPrefix.get("foo:foo")).to.eql("baz");
+    expect(
+      await redisWOPrefix.get(Buffer.from([0x66, 0x6f, 0x6f, 0x3a, 0xff]))
+    ).to.eql("baz");
+  });
+
+  it("should support buffer as keyPrefix", async () => {
+    // @ts-expect-error
+    const redis = new Redis({ keyPrefix: Buffer.from([0xff]) });
+    await redis.mset("bar", Buffer.from("baz"), "foo", Buffer.from("bar"));
+    await redis.set(Buffer.from([0xff]), Buffer.from("baz"));
+
+    const redisWOPrefix = new Redis();
+    expect(
+      await redisWOPrefix.get(Buffer.from([0xff, 0x62, 0x61, 0x72]))
+    ).to.eql("baz");
+    expect(
+      await redisWOPrefix.get(Buffer.from([0xff, 0x66, 0x6f, 0x6f]))
+    ).to.eql("bar");
+    expect(await redisWOPrefix.get(Buffer.from([0xff, 0xff]))).to.eql("baz");
+  });
+
   it("should support key prefixing for zunionstore", (done) => {
     const redis = new Redis({ keyPrefix: "foo:" });
     redis.zadd("zset1", 1, "one");