fix: keep sentinels of options immutable

Close #936

Author: luin

lib/connectors/SentinelConnector/SentinelIterator.ts

@@ -13,8 +13,11 @@ function isSentinelEql(
 export default class SentinelIterator
   implements Iterator<Partial<ISentinelAddress>> {
   private cursor: number = 0;
+  private sentinels: Array<Partial<ISentinelAddress>>;
 
-  constructor(private sentinels: Array<Partial<ISentinelAddress>>) {}
+  constructor(sentinels: Array<Partial<ISentinelAddress>>) {
+    this.sentinels = sentinels.slice(0);
+  }
 
   next() {
     const done = this.cursor >= this.sentinels.length;

test/functional/sentinel.ts

@@ -1,6 +1,7 @@
 import Redis from "../../lib/redis";
 import MockServer from "../helpers/mock_server";
 import { expect } from "chai";
+import * as sinon from "sinon";
 
 describe("sentinel", function() {
   describe("connect", function() {
@@ -121,6 +122,12 @@ describe("sentinel", function() {
 
     it("should add additionally discovered sentinels when resolving successfully", function(done) {
       var sentinels = [{ host: "127.0.0.1", port: 27379 }];
+      var cloned;
+
+      sinon.stub(sentinels, "slice").callsFake((start, end) => {
+        cloned = [].slice.call(sentinels, start, end);
+        return cloned;
+      });
 
       var sentinel = new MockServer(27379, function(argv) {
         if (argv[0] === "sentinel" && argv[1] === "get-master-addr-by-name") {
@@ -136,7 +143,7 @@ describe("sentinel", function() {
       sentinel.once("disconnect", function() {
         redis.disconnect();
         master.disconnect(function() {
-          expect(sentinels.length).to.eql(2);
+          expect(cloned.length).to.eql(2);
           sentinel.disconnect(done);
         });
       });

test/unit/connectors/SentinelConnector/SentinelIterator.ts

@@ -0,0 +1,18 @@
+import { expect } from "chai";
+import SentinelIterator from "../../../../lib/connectors/SentinelConnector/SentinelIterator";
+
+describe("SentinelIterator", () => {
+  it("keep the options immutable", () => {
+    function getSentinels() {
+      return [{ host: "127.0.0.1", port: 30001 }];
+    }
+    const sentinels = getSentinels();
+
+    const iter = new SentinelIterator(sentinels);
+    iter.add({ host: "127.0..0.1", port: 30002 });
+
+    expect(sentinels).to.eql(getSentinels());
+    expect(iter.next().value.port).to.eql(30001);
+    expect(iter.next().value.port).to.eql(30002);
+  });
+});