Add isTestRunner utility

[yannbf]

Release notes

The test-runner adds a StorybookTestRunner entry to the browser's user agent. You can use it to determine if a story is rendering in the context of the test runner. This might be useful if you want to disable certain features in your stories when running in the test runner, though it's likely an edge case.

export const MyStory = () => {
  const isTestRunner = window.navigator.userAgent.match(/StorybookTestRunner/)
  return (
    <div>
      <p>Is this story running in the test runner?</p>
      <p>{isTestRunner ? 'Yes' : 'No'}</p>
    </div>
  );
};

Given that this check is happening in the browser, it is only applicable in the following scenarios:

• inside of a render/template function of a story
• inside of a play function
• inside of preview.js
• inside any other code that is executed in the browser

📦 Published PR as canary version: 0.8.0--canary.198.d45feb9.0

✨ Test out this PR locally via:

npm install @storybook/test-runner@0.8.0--canary.198.d45feb9.0
# or 
yarn add @storybook/test-runner@0.8.0--canary.198.d45feb9.0

Version

Published prerelease version: v0.8.0-next.0

Changelog

🚀 Enhancement

• Add isTestRunner utility #198 (@yannbf @IanVS)

Authors: 2

• Ian VanSchooten (@IanVS)
• Yann Braga (@yannbf)

[codecov-commenter]

Codecov Report

Base: 76.53% // Head: 76.63% // Increases project coverage by +0.09% 🎉

Coverage data is based on head (4010e3e) compared to base (aa45827).
Patch coverage: 80.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             next     #198      +/-   ##
==========================================
+ Coverage   76.53%   76.63%   +0.09%     
==========================================
  Files          11       12       +1     
  Lines         179      184       +5     
  Branches       37       38       +1     
==========================================
+ Hits          137      141       +4     
- Misses         42       43       +1     

Impacted Files	Coverage Δ
.storybook/preview.js	80.00% <80.00%> (ø)

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[tmeasday]

Looks great! Thanks @yannbf

[github-actions]

🚀 PR was released in v0.8.0 🚀