how to clear global var between tests in nodejs? - node.js

Question

I have 2 tests which each one them pass but when i run them together the second test fails.
I have this global var (CURR_GUID) which i want to clear between the tests but i am not sure how to do that.
Since it is not cleared between the tests , its value is still "1111111" and not null.
Any idea?
Class W
"use strict";
var CURR_GUID = null;
class W {
constructor() {
console.log("W ctor")
}
async getDataFromDb() {
if (CURR_GUID) {
return CURR_GUID;
} else {
this.db = require("./Connection").getDb();
console.log("W getDataFromDb")
let res = null;
res = await this.db.one("SELECT guid FROM table", ["NONE"]);
return res.guid;
}
}
async saveGuid(guid) {
this.db = require("./Connection").getDb();
await this.db.none("update table set guid=$1", [guid]);
CURR_GUID = guid;
console.log("currr is" + CURR_GUID);
}
}
module.exports = W;
Class X
"use strict";
const wDao = new (require("../db/W"))();
class X {
async getGuid() {
console.log("X getGuid")
let guid = await wDao.getDataFromDb();
console.log("got guid " + guid);
await wDao.saveGuid(guid);
return guid;
}
}
module.exports = X;
Test.spec.js
const chai = require("chai");
const expect = chai.expect;
const X = require("../src/service/X");
const Connection = require("../src/db/Connection");
const sinon = require("sinon");
describe("component_test", function () {
afterEach(function () {
this.dbStub.restore();
});
it("X_component_test", async function () {
var db = {
one: async () => {
return {
guid: '1111111',
created_on: "123"
}
},
none: async () => {
}
};
this.dbStub = sinon.stub(Connection, "getDb").returns(db);
var dao = new X();
var guid = await dao.getGuid();
expect(guid).to.equal('1111111');
});
it("X_component_test_2", async function () {
var db = {
one: async () => {
return {
guid: '222222',
created_on: "123"
}
},
none: async () => {
}
};
this.dbStub = sinon.stub(Connection, "getDb").returns(db);
var dao = new X();
var guid = await dao.getGuid();
expect(guid).to.equal('222222');
});
});

Answer 1

While it should be possible to achieve the desired result by deleting W and X modules from require.cache in afterEach hook, it might be better to modify the source code a bit so that it can be tested without cache manipulations.
Class W
Turn CURR_GUID variable into an instance property.
"use strict";
class W {
constructor() {
console.log("W ctor");
this.CURR_GUID = null;
}
async getDataFromDb() {
if (this.CURR_GUID) {
return this.CURR_GUID;
} else {
this.db = require("./Connection").getDb();
console.log("W getDataFromDb")
let res = null;
res = await this.db.one("SELECT guid FROM table", ["NONE"]);
return res.guid;
}
}
async saveGuid(guid) {
this.db = require("./Connection").getDb();
await this.db.none("update table set guid=$1", [guid]);
this.CURR_GUID = guid;
console.log("currr is" + this.CURR_GUID);
}
}
module.exports = W;
Class X
Turn wDao from variable into an instance property
"use strict";
const WDao = require("../db/W");
class X {
constructor() {
this.wDao = new WDao();
}
async getGuid() {
console.log("X getGuid")
let guid = await this.wDao.getDataFromDb();
console.log("got guid " + guid);
await this.wDao.saveGuid(guid);
return guid;
}
}
module.exports = X;
In this way every test should work with fresh instances of W and X that do not depend on the closure state.