https://www.notion.so/Jest-Issues-831d928ced3b451e9d2c8a264ada0f7e
Configurations for DOM Support
Use document object and methods like document.querySelectorAll…
_setup.ts
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import "jsdom-global/register";
jest.config.js
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module.exports = {
verbose: true,
transform: {
".(ts|tsx)": "<rootdir>/node_modules/ts-jest/preprocessor.js",
".+\\.(css|styl|less|sass|scss|png|jpg|ttf|woff|woff2)$": "jest-transform-stub",
},
testEnvironment: "node",
testRegex: "(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$",
setupTestFrameworkScriptFile: "./test/_setup.ts",
moduleFileExtensions: ["ts", "tsx", "js"],
coveragePathIgnorePatterns: ["/node_modules/", "/test/", "src/index.ts"],
coverageThreshold: {
global: {
branches: 0,
functions: 0,
lines: 0,
statements: 0,
},
},
collectCoverageFrom: ["src/**/*.{js,ts,tsx}"],
};
UT Example for Promise
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// ut passed requires `done` called
it("should return a promise with callback and title", done => {
confirm("Promise confirm").then(() => {
done();
});
document.querySelectorAll<htmlelement>(".btn")[1].click();
});
// reject promise
it("test reject promise", async () => {
// do not use `Promise.reject`, because returns Promise immediately
const mockP = jest.fn(() => Promise.reject("err"));
await delay(1, mockP()).catch(() => {
// nothing
});
expect(mockP.mock.calls.length).toBe(1);
});