Using "expect.not.stringContaining" produces a "val.toAsymmetricMatcher is not a function" error

[sangaline]

🐛 Bug Report

The example from the documentation for expectnotstringcontaingstring works when the substring isn't contained, but it gives a val.toAsymmetricMatcher is not a function error when the substring is contained. It's expected that the test should fail, but this does not seem like the expected error in this scenario.

To Reproduce

Create a file called string.test.js with the following contents.

describe('not.stringContaining', () => {
  const expected = 'are you?';

  it('matches if the actual string does not contain the expected substring', () => {
    expect('How are you?').toEqual(expect.not.stringContaining(expected));
  });
});

Then run the following.

jest

Expected behavior

The expected behavior is that this would produce an informative error about the substring being contained within the "How are you?" string when it is expected not to be.

Link to repl or repo (highly encouraged)

Here is a link to repl.it, but they're using version 22 and the error is different with that version. On v22 it is

TypeError: Cannot read property 'stringContaining' of undefined

and on v23 it is

TypeError: val.toAsymmetricMatcher is not a function

Run npx envinfo --preset jest

Paste the results here:

npx: installed 1 in 1.148s

  System:
    OS: Linux 4.9 Amazon Linux AMI 2017.09
    CPU: x64 Intel(R) Xeon(R) CPU E5-2676 v3 @ 2.40GHz
  Binaries:
    Node: 9.4.0 - ~/.nvm/versions/node/v9.4.0/bin/node
    Yarn: 1.7.0 - ~/.nvm/versions/node/v9.4.0/bin/yarn
    npm: 5.6.0 - ~/.nvm/versions/node/v9.4.0/bin/npm
  npmPackages:
    jest: ^23.0.0 => 23.0.0 

[SimenB]

Thanks for the report! Opened up a PR for it: #6272

[jayarjo]

How to mitigate that error - TypeError: val.toAsymmetricMatcher is not a function in a custom (user defined) matcher?

[github-actions]

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