add Datahandler constructor test

Signed-off-by: Aleksandr Zinin <[email protected]>

test/unit/DataHandler.ts

@@ -0,0 +1,30 @@
+import * as sinon from "sinon";
+import { expect } from "chai";
+import DataHandler from "../../lib/DataHandler";
+
+describe("DataHandler", () => {
+  afterEach(() => {
+    sinon.restore();
+  });
+
+  describe("constructor()", () => {
+    it("should add a data handler to the redis stream properly", () => {
+      const dataHandledable = {
+        stream: {
+          prependListener: sinon.spy(),
+          resume: sinon.spy(),
+        },
+      };
+      new DataHandler(dataHandledable, {});
+
+      expect(dataHandledable.stream.prependListener.calledOnce).to.eql(true);
+      expect(dataHandledable.stream.resume.calledOnce).to.eql(true);
+
+      expect(
+        dataHandledable.stream.resume.calledAfter(
+          dataHandledable.stream.prependListener
+        )
+      ).to.eql(true);
+    });
+  });
+});