不变违规：元素类型无效（Jest + TSX + StyledComponents）

Question

I have been struggling with running test using Jest when I use styled-components .

I took the example code from styled-components/jest

import * as React from 'react'
import styled from 'styled-components'
import * as TestRenderer from 'react-test-renderer'
import 'jest-styled-components'

const Button = styled.button`
  color: red;
`

test('it works', () => {
  const tree = TestRenderer.create(<Button />).toJSON()
  expect(tree).toMatchSnapshot()
  expect(tree).toHaveStyleRule('color', 'red')
})

and I always and up with following error:

 Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object.

The test file is .tsx. Jest config is following:

module.exports = {
    "roots": [
        "<rootDir>/src"
    ],
    "transform": {
        "^.+\\.tsx?$": "ts-jest"
    },
    "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$",
    "moduleFileExtensions": [
        "ts",
        "tsx",
        "js",
        "jsx",
        "json",
        "node"
    ]
}

Answer 1

Well, eventually I ended up using enzyme for testing. Did not really resolve this, but managed to make it working.

Also decided not to use jest-styled-components since last versions have some troubles on its own. Hopefully I will manage that later.

import * as React from 'react'
import styled from 'styled-components'

const Button = styled.button`
color: red;
`

test('it works', () => {
const tree = shallow(<Button />);
expect(tree).toMatchSnapshot()
})

Needless to say that you must update your jest.config.js to make shallow working:

"snapshotSerializers": [
  "enzyme-to-json/serializer"
]