Do you like to write paths in jest.mock() calls? I don't. If you don't like too, then you're in the right place. Probably.
The following input:
import A from "./a";
import { B } from "./b";
import * as C from "./c";
// this is just placeholder for transformation, will be removed from output
jest.mockObj(A, C.C1);
jest.mockFn(B, C.C2);will be transformed to:
jest.mock("./a", () => {
const o = {
"default": "A"
};
Object.defineProperty(o, "__esModule", { value: true });
return o;
});
jest.mock("./b", () => {
const o = {
"B": jest.fn().mockName("B"),
};
Object.defineProperty(o, "__esModule", { value: true });
return o;
});
jest.mock("c", () => {
const o = {
"C1": "C1",
"C2": jest.fn().mockName("C.C2"),
};
Object.defineProperty(o, "__esModule", { value: true });
Object.defineProperty(o.C2, "name", { value: "C.C2" });
return o;
});
import A from "./a";
import { B } from "./b";
import * as C from "c";You can say you have to write paths in import calls anyway. But you're wrong if you use IDE/editor with autoimporting feature - just start to write symbol name and you'll get the imported path for free.
jest.mockObj(...args: any[]);
Creates string mock with default implementation to return identifier name. Very handy to mock react components for ReactTestRenderer:
// comp1.js
import InnerComp from "./inner";
export const Comp = () => <div><InnerComp /></div>;
// comp1.spec.js
import InnerComp from "../inner";
import Comp from "../comp1";
// Easy including with IDE autoimporting
jest.mockObj(InnerComp);
const testRenderer = TestRenderer.create(<Comp />);
expect(testRenderer).toMatchSnapshot(); // <div><InnerComp /></div>You can pass implementation for module export too:
import { B1, B2 } from "./b";
jest.mockObj(B1, "i'm b");
jest.mockObj(B2, () => "test");This will be transformed to:
jest.mock("./b", () => {
const o = {
"B1": "i'm b",
"B2": () => "test",
};
Object.defineProperty(o, "__esModule", { value: true });
return o;
});Note Requires jest 22.0+
jest.mockFn(...args: any[]);Creates jest.fn() mock calls for specified symbols
import { B1, B2 } from "./b";
jest.mockFn(B1, B2);This will be transformed to:
jest.mock("./b", () => {
const o = {
"B1": jest.fn().mockName("B1"),
"B2": jest.fn().mockName("B2"),
};
Object.defineProperty(o, "__esModule", { value: true });
Object.defineProperty(o.B1, "name", { value: "B1" });
Object.defineProperty(o.B2, "name", { value: "B2" });
return o;
});Given some file:
export function func1() { return "func1"; }
export function func2() { return "func2"; }
export const a = "a";Want to mock only func1 but leave original behavior for func2/a ? It's possible, put into your babel configuration:
plugins: [["jest-easy-mock", { requireActual: true }]]And following test file:
import { func1, func2, a } from "./a";
jest.mockObj(func1, () => "test");
func1(); // test
func2(); // func2
console.log(a); // awill be transformed to:
jest.mock("./a", () => {
const a = require.requireActual("./a");
const o = {
...a,
func1: () => "test",
};
Object.defineProperty(o, "__esModule", { value: true });
return o;
});You need either spread transform enabled in the babel conf, or node 8.4+
Nesting is being supported for one level deep from module export:
import A, { A2 } from "./a";
import * as C from "c";
jest.mockObj(A.ANest, C.Components.Comp1);
jest.mockObj(A2.A2Nest, jest.fn().mockReturnValue("someval")); // declarations from the same module will be merged into one module mockwill result to:
jest.mock("./a", () => {
const o = {
"default": {
"ANest": "ANest"
},
"A2": {
"A2Nest": jest.fn().mockReturnValue("someval");
}
};
Object.defineProperty(o, "__esModule", { value: true });
return o;
});
jest.mock("c", () => {
const o = {
"Components": {
"Comp1": "Comp1"
}
};
Object.defineProperty(o, "__esModule", { value: true });
return o;
});
import A, { A2 } from "./a";
import * as C from "c";For explicit module mocks with jest.mock, jest.doMock, jest.unmock and jest.dontMock the transformation will be ignored:
import { A } from "a";
jest.mock("a");
// the order doesn't matter
jest.mockObj(A);will be transformed to:
import { A } from "a";
jest.mock("a");npm install babel-plugin-jest-easy-mock --save-dev
Add to your .babelrc or in .babelrc.js:
plugins: ["jest-easy-mock"]
Plugin exposes few configuration options:
jestIdentifier - Jest identifier used to create actual mocks
requireActual - Do require.requireActual for partial module mocks
ignoreIdentifiers - List of call expression identifiers to ignore the mocking
identfiers - List of call identifiers configuration to do the mocking
interface IdentifierConfiguration {
/**
* Identifier name
*/
name: string;
/**
* Remove identifier from transpilation output
*/
remove: boolean;
/**
* Identifier type. "name" will mock with import name, "mock" will mock with jest.fn()
*/
type: "name" | "mock",
}Default config:
{
jestIdentifier: "jest",
mockIdentifiers: ["jest.mock", "jest.doMock", "jest.unmock", "jest.dontMock"],
identifiers: [
{
name: "jest.mockObj",
remove: true,
type: "name",
},
{
name: "jest.mockFn",
remove: true,
type: "mock",
}
],
requireActual: false,
}To pass custom conviguration add to your babelrc/baberc.js:
"plugins": [
["jest-easy-mock", {
"requireActual": true,
"identifiers": [
{
"name": "a.b.c",
"type": "mock",
"remove": false
},
{
"name": "jest.mockObj",
"type": "name",
"remove": true
}
]
}]
]Unfortunately TS when compiling to commonjs modules, produces very hard to statically understand structure, so use "module": "es2015" for output and let babel to transform the output with babel-plugin-transform-es2015-modules-commonjs. Altenatively, you can just use babel for all TS transpilation with preset babel-preset-typescript and use TS only for editor/IDE purposes.