Prettier is used by `toMatchInlineSnapshot`, but it is not a dependency of `jest`

🐛 Bug Report

Prettier is used by jest for toMatchInlineSnapshot, but since it’s not a dependency of jest, toMatchInlineSnapshot only works if some other package depends on prettier (or it’s in the user’s package.json).

To Reproduce

Steps to reproduce the behavior:

• Make a new directory and run yarn init --yes inside it
• Run yarn add jest
• Create a test using the toMatchInlineSnapshot matcher, eg:

  expect(2 + 2).toMatchInlineSnapshot()
  

• Notice that the test fails with an error indicating that prettier cannot be found.

Expected behavior

Test passes with no issues

npx envinfo --preset jest

  System:
    OS: macOS 10.14.4
    CPU: x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
  Binaries:
    Node: 12.1.0 - /usr/local/bin/node
    Yarn: 1.13.0 - /usr/local/bin/yarn
    npm: 6.9.0 - /usr/local/bin/npm
  npmPackages:
    jest: 24.8.0 => 24.8.0

[UziTech]

looks like it is supposed to throw a descriptive error message:

https://github.com/facebook/jest/blob/fa4cbbf87cb3c97fe44f1fee30663715a9dbba71/packages/jest-snapshot/src/inline_snapshots.ts#L33-L35

The error message that I get with jest-cli@25.4.0 is:

Cannot find module 'prettier' from 'setup_jest_globals.js'

[SimenB]

Oh, nice!

A descriptive error message saying “you need to install prettier” might be good enough, too

yeah, we should definitely to that as a first step regardless. #7744