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cpojer merged 1 commit into from
Oct 26, 2016
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Stop using Node --inspect option in the docs on debugging #1998

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18 changes: 15 additions & 3 deletions docs/Troubleshooting.md
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Expand Up @@ -11,17 +11,29 @@ Uh oh, something went wrong? Use this guide to resolve issues with Jest.

### Tests are Failing and You Don't Know Why

Try using the debugger built into >= Node 6.3.
Try using the debugging support built into Node.

Place a `debugger;` statement in any of your tests, and then, in your project's directory, run:

`node --debug-brk --inspect ./node_modules/.bin/jest -i [any other arguments here]`
`node --debug-brk ./node_modules/.bin/jest -i [any other arguments here]`

This will run Jest in a Node process that an external debugger can connect to. Note that the process
will pause until the debugger has connected to it.

For example, to connect the [Node Inspector](https://github.com/node-inspector/node-inspector)
debugger to the paused process, you would first install it (if you don't have it installed already):

`npm install -g node-inspector`

Then simply run it:

`node-inspector`

This will output a link that you can open in Chrome. After opening that link, the Chrome Developer Tools will be displayed, and a breakpoint will be set at the first line of the Jest CLI script (this is done simply to give you time to open the developer tools and to prevent Jest from executing before you have time to do so). Click the button that looks like a "play" button in the upper right hand side of the screen to continue execution. When Jest executes the test that contains the `debugger` statement, execution will pause and you can examine the current scope and call stack.

*Note: the `-i` cli option makes sure Jest runs test in the same process rather than spawning processes for individual tests. Normally Jest parallelizes test runs across processes but it is hard to debug many processes at the same time.*

More information on the V8 inspector can be found here: https://nodejs.org/api/debugger.html#debugger_v8_inspector_integration_for_node_js
More information on Node debugging can be found here: https://nodejs.org/api/debugger.html

### Caching Issues

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