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Use ts-jest in client tests #547

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brandonchinn178 opened this issue Jul 16, 2021 · 1 comment · May be fixed by #549
Open

Use ts-jest in client tests #547

brandonchinn178 opened this issue Jul 16, 2021 · 1 comment · May be fixed by #549
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@brandonchinn178
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babel-jest does not type check the tests (https://kulshekhar.github.io/ts-jest/docs/babel7-or-ts). However, we can't just switch to ts-jest, because we should re-use the same babel config used by next.

After this work is done, write a ticket in https://github.com/vercel/next.js/issues to switch their jest example to use ts-jest

@brandonchinn178
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brandonchinn178 commented Jul 16, 2021

The following issues should also be ticketed in order to get ts-jest working:

Babel will generate ESM-style imports

  ● Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    /Users/brandino/repos/worship-mate/client/jest/setup.tsx:21
    import React from "react";
    ^^^^^^

    SyntaxError: Cannot use import statement outside a module

one difference when changing to ts-jest is that ts-jest will convert the typescript into javascript first, before passing to babel.

  • babel-jest:
    var _react = _interopRequireDefault(require("react"));
    var __jsx = _react.default.createElement;
  • ts-jest, without automatic (this is injected by jsx-pragma):
    import React from "react";
    var __jsx = React.createElement;
  • ts-jest, with automatic:
    var _reactJsxDevRuntime = require("react/jsx-dev-runtime");

Why not always use automatic?

Refs:

Snapshots lose styled-components display name

styled-components/babel-plugin-styled-components#343

@brandonchinn178 brandonchinn178 linked a pull request Jul 17, 2021 that will close this issue
@brandonchinn178 brandonchinn178 self-assigned this Jul 17, 2021
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