mock nodemailer.createTransport.sendMail with jest

I have some code which uses the nodemailer module.

In the router (router.js), I have

const transporter = nodeMailer.createTransport(emailArgs);

Then inside the route (/login) I have:

...

return transporter.sendMail(mailOptions);

I'm trying to test this route using the jest testing framework. I'm having some trouble mocking out the call to sendMail. I read this nice blogpost about how to use jest mocking, but I'm getting this error:

TypeError: Cannot read property 'sendMail' of undefined

And indeed when I check the value of transporter it's undefined.

Here is my testing code (which doesn't work):

import request from "supertest";

import router from "./router";



jest.mock("nodemailer");



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);

        // TODO not sure how to express the expect statement here

    });

});

So my question is how do I mock out a method of an instance of a class which is returned by a module?

edited Nov 22 '18 at 10:23

skyboyer

3,75311229

asked Nov 21 '18 at 21:14

BlackSheep

1,49473259

add a comment |

I have some code which uses the nodemailer module.

In the router (router.js), I have

const transporter = nodeMailer.createTransport(emailArgs);

Then inside the route (/login) I have:

...

return transporter.sendMail(mailOptions);

TypeError: Cannot read property 'sendMail' of undefined

And indeed when I check the value of transporter it's undefined.

Here is my testing code (which doesn't work):

import request from "supertest";

import router from "./router";



jest.mock("nodemailer");



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);

        // TODO not sure how to express the expect statement here

    });

});

So my question is how do I mock out a method of an instance of a class which is returned by a module?

edited Nov 22 '18 at 10:23

skyboyer

3,75311229

asked Nov 21 '18 at 21:14

BlackSheep

1,49473259

add a comment |

I have some code which uses the nodemailer module.

In the router (router.js), I have

const transporter = nodeMailer.createTransport(emailArgs);

Then inside the route (/login) I have:

...

return transporter.sendMail(mailOptions);

TypeError: Cannot read property 'sendMail' of undefined

And indeed when I check the value of transporter it's undefined.

Here is my testing code (which doesn't work):

import request from "supertest";

import router from "./router";



jest.mock("nodemailer");



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);

        // TODO not sure how to express the expect statement here

    });

});

So my question is how do I mock out a method of an instance of a class which is returned by a module?

edited Nov 22 '18 at 10:23

skyboyer

3,75311229

asked Nov 21 '18 at 21:14

BlackSheep

1,49473259

I have some code which uses the nodemailer module.

In the router (router.js), I have

const transporter = nodeMailer.createTransport(emailArgs);

Then inside the route (/login) I have:

...

return transporter.sendMail(mailOptions);

TypeError: Cannot read property 'sendMail' of undefined

And indeed when I check the value of transporter it's undefined.

Here is my testing code (which doesn't work):

import request from "supertest";

import router from "./router";



jest.mock("nodemailer");



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);

        // TODO not sure how to express the expect statement here

    });

});

So my question is how do I mock out a method of an instance of a class which is returned by a module?

node.js unit-testing mocking jestjs nodemailer

edited Nov 22 '18 at 10:23

skyboyer

3,75311229

asked Nov 21 '18 at 21:14

BlackSheep

1,49473259

edited Nov 22 '18 at 10:23

skyboyer

3,75311229

asked Nov 21 '18 at 21:14

BlackSheep

1,49473259

edited Nov 22 '18 at 10:23

skyboyer

3,75311229

edited Nov 22 '18 at 10:23

skyboyer

3,75311229

edited Nov 22 '18 at 10:23

skyboyer

3,75311229

asked Nov 21 '18 at 21:14

BlackSheep

1,49473259

asked Nov 21 '18 at 21:14

BlackSheep

1,49473259

asked Nov 21 '18 at 21:14

BlackSheep

1,49473259

add a comment |

1 Answer
1

active

oldest

votes

I ran into the same problem and found a solution. Here is what I've discovered:

With jest.mock("nodemailer"); you tell jest to replace nodemailer with an auto-mock. This means every property of nodemailer is replaced with an empty mock function (similar to jest.fn()).

That is the reason why you get the error TypeError: Cannot read property 'sendMail' of undefined.
In order to have something useful, you have to define the mock function of nodemailer.createTransport.

In our case we wan't to have an object with a property sendMail. We could do this with nodemailer.createTransport.mockReturnValue({"sendMail": jest.fn()});. Since you may want to test if sendMail was called, it is a good idea to create that mock function before hand.

Here is a complete example of your testing code:

import request from "supertest";

import router from "./router";



const sendMailMock = jest.fn(); // this will return undefined if .sendMail() is called



// In order to return a specific value you can use this instead

// const sendMailMock = jest.fn().mockReturnValue(/* Whatever you would expect as return value */);



jest.mock("nodemailer");



const nodemailer = require("nodemailer"); //doesn't work with import. idk why

nodemailer.createTransport.mockReturnValue({"sendMail": sendMailMock});



beforeEach( () => {

    sendMailMock.mockClear();

    nodemailer.createTransport.mockClear();

});



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);



        // TODO not sure how to express the expect statement here

        expect(sendMailMock).toHaveBeenCalled();

    });

});

answered Jan 29 at 20:08

Benedikt Bock

471625

add a comment |

Your Answer

StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});

}
});

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53420562%2fmock-nodemailer-createtransport-sendmail-with-jest%23new-answer', 'question_page');
}
);

Post as a guest

Name

Required, but never shown

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

I ran into the same problem and found a solution. Here is what I've discovered:

With jest.mock("nodemailer"); you tell jest to replace nodemailer with an auto-mock. This means every property of nodemailer is replaced with an empty mock function (similar to jest.fn()).

Here is a complete example of your testing code:

import request from "supertest";

import router from "./router";



const sendMailMock = jest.fn(); // this will return undefined if .sendMail() is called



// In order to return a specific value you can use this instead

// const sendMailMock = jest.fn().mockReturnValue(/* Whatever you would expect as return value */);



jest.mock("nodemailer");



const nodemailer = require("nodemailer"); //doesn't work with import. idk why

nodemailer.createTransport.mockReturnValue({"sendMail": sendMailMock});



beforeEach( () => {

    sendMailMock.mockClear();

    nodemailer.createTransport.mockClear();

});



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);



        // TODO not sure how to express the expect statement here

        expect(sendMailMock).toHaveBeenCalled();

    });

});

answered Jan 29 at 20:08

Benedikt Bock

471625

add a comment |

I ran into the same problem and found a solution. Here is what I've discovered:

With jest.mock("nodemailer"); you tell jest to replace nodemailer with an auto-mock. This means every property of nodemailer is replaced with an empty mock function (similar to jest.fn()).

Here is a complete example of your testing code:

import request from "supertest";

import router from "./router";



const sendMailMock = jest.fn(); // this will return undefined if .sendMail() is called



// In order to return a specific value you can use this instead

// const sendMailMock = jest.fn().mockReturnValue(/* Whatever you would expect as return value */);



jest.mock("nodemailer");



const nodemailer = require("nodemailer"); //doesn't work with import. idk why

nodemailer.createTransport.mockReturnValue({"sendMail": sendMailMock});



beforeEach( () => {

    sendMailMock.mockClear();

    nodemailer.createTransport.mockClear();

});



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);



        // TODO not sure how to express the expect statement here

        expect(sendMailMock).toHaveBeenCalled();

    });

});

answered Jan 29 at 20:08

Benedikt Bock

471625

add a comment |

I ran into the same problem and found a solution. Here is what I've discovered:

With jest.mock("nodemailer"); you tell jest to replace nodemailer with an auto-mock. This means every property of nodemailer is replaced with an empty mock function (similar to jest.fn()).

Here is a complete example of your testing code:

import request from "supertest";

import router from "./router";



const sendMailMock = jest.fn(); // this will return undefined if .sendMail() is called



// In order to return a specific value you can use this instead

// const sendMailMock = jest.fn().mockReturnValue(/* Whatever you would expect as return value */);



jest.mock("nodemailer");



const nodemailer = require("nodemailer"); //doesn't work with import. idk why

nodemailer.createTransport.mockReturnValue({"sendMail": sendMailMock});



beforeEach( () => {

    sendMailMock.mockClear();

    nodemailer.createTransport.mockClear();

});



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);



        // TODO not sure how to express the expect statement here

        expect(sendMailMock).toHaveBeenCalled();

    });

});

answered Jan 29 at 20:08

Benedikt Bock

471625

I ran into the same problem and found a solution. Here is what I've discovered:

With jest.mock("nodemailer"); you tell jest to replace nodemailer with an auto-mock. This means every property of nodemailer is replaced with an empty mock function (similar to jest.fn()).

Here is a complete example of your testing code:

import request from "supertest";

import router from "./router";



const sendMailMock = jest.fn(); // this will return undefined if .sendMail() is called



// In order to return a specific value you can use this instead

// const sendMailMock = jest.fn().mockReturnValue(/* Whatever you would expect as return value */);



jest.mock("nodemailer");



const nodemailer = require("nodemailer"); //doesn't work with import. idk why

nodemailer.createTransport.mockReturnValue({"sendMail": sendMailMock});



beforeEach( () => {

    sendMailMock.mockClear();

    nodemailer.createTransport.mockClear();

});



describe("", () => {

...



    test("", async () => {

        // 1 - 200 status code; 2 - check email was sent

        expect.assertions(2);



        const response = await request(router)

            .post("/login")

            // global variable

            .send({ "email": email })

            .set("Accept", "application/json")

            .expect("Content-Type", /json/);



        // should complete successfully

        expect(response.status).toBe(200);



        // TODO not sure how to express the expect statement here

        expect(sendMailMock).toHaveBeenCalled();

    });

});

answered Jan 29 at 20:08

Benedikt Bock

471625

answered Jan 29 at 20:08

Benedikt Bock

471625

answered Jan 29 at 20:08

Benedikt Bock

471625

answered Jan 29 at 20:08

Benedikt Bock

471625

add a comment |

draft saved

draft discarded

Thanks for contributing an answer to Stack Overflow!

Please be sure to answer the question. Provide details and share your research!

But avoid …

Asking for help, clarification, or responding to other answers.

Making statements based on opinion; back them up with references or personal experience.

To learn more, see our tips on writing great answers.

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Name

Required, but never shown

Name

Required, but never shown

This page is only for reference, If you need detailed information, please check here

Search This Blog

Ufyukyu