angular-cli: Cannot import json files when running ng test

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- [ ] feature request


@angular/cli: 1.1.3
node: 8.1.0
os: win32 x64
@angular/animations: 4.2.4
@angular/common: 4.2.4
@angular/compiler: 4.2.4
@angular/core: 4.2.4
@angular/flex-layout: 2.0.0-beta.8
@angular/forms: 4.2.4
@angular/http: 4.2.4
@angular/material: 2.0.0-beta.7
@angular/platform-browser: 4.2.4
@angular/platform-browser-dynamic: 4.2.4
@angular/router: 4.2.4
@angular/cli: 1.1.3
@angular/compiler-cli: 4.2.4

Repro steps.

import sampleData from './data.json';

// check if sampleData is undefined or not - in ng serve it has the correct value, in ng test it's undefined

You can see more details in this repo -

  • npm start - you should see the content of sample.json
  • npm test - the exception will be thrown that it’s undefined (the exception is just there to demonstrate that it’s undefined)

Desired functionality.

since I import the json file as a module, it should be imported the same way in tests, like it is done for the application to be served or compiled

About this issue

  • Original URL
  • State: closed
  • Created 7 years ago
  • Reactions: 6
  • Comments: 16 (1 by maintainers)

Most upvoted comments

You need to have typings for jso file. Put this to your typing.d.ts

declare module '*.json' { const value: any; export default value; }

Then use import * as sampleData from './data.json';

@Juansasa works for me until the latest version of angular/cli (1.6.2).

It seems that somehow this issue is related to this merge

This merge force to use module: 'commonjs' in compilerOptions of tsconfig.

// Forcing commonjs seems to drastically improve rebuild speeds on webpack.
    // Dev builds on watch mode will set this option to true.
    if (wco.buildOptions.forceTsCommonjs) {
        options.compilerOptions.module = 'commonjs';

And by default, ng test use commonjs either (seesrc/app/tsconfig.spec.ts in your project).

I don’t know what is the difference between commonjs and es2015. Any idea why?


import data from './data.json'; // not work
import * as data from './data.json'; // work
const data = require('./data.json'); // work


I think this is because typescript compile in different way. See example below.

// test.ts
import data1 from './data.json';
import * as data2 from './data.json';

console.log(data1 !== undefined);
console.log(data2 !== undefined);

// data.json
  "foo": "bar"
// typescript 2.6.2
tsc --module commonjs test.ts
// output test.js
"use strict";
exports.__esModule = true;
var data_json_1 = require("./data.json");
var data2 = require("./data.json");
console.log(data_json_1["default"] !== undefined);
console.log(data2 !== undefined);
// output of node test.js

To clarify i’ve been using this trick for quite some time since Angular first released until now at version 6 everything just work.

typings.d.ts declare module '*.json' { const value: any; export default value; }

Component import import * as JSON from './file.json';

I’ll create a sample project and post it here to clear this issue once for all and will post it here.

Update Angular 6 JSON import

The same problem here using angular 6. I created a library with the new command ng generate library. In the new library component created I’m importing a json file in the same path of the library component. When I try to build I get Cannot find module './palettes.json'. How to solve it?

I’ll have a look but generally we don’t really support loading anything but js/ts files as ES6 imports. It is inconsistent that it works in one case and not the other though.