| 1 | # Debugging
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| 2 |
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| 3 | When a value generated by `any` causes a test to fail inconsistently, it can
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| 4 | be incredibly difficult to track down the failing conditions. In order to
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| 5 | reliably reproduce the problem, you need to be able to get `any` to repeatedly
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| 6 | produce the same value.
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| 7 |
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| 8 | ## Determine the seed
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| 9 |
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| 10 | The [debug](https://www.npmjs.com/package/debug) library is in place to enable
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| 11 | revealing the `seed` that was used for the randomness of generated values. This
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| 12 | means that the `seed` is not displayed by default, but can be revealed by
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| 13 | instructing `debug` to output logs for `any`:
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| 14 |
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| 15 | ```sh
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| 16 | $ DEBUG=any mocha --recursive test/unit/
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| 17 |
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| 18 | Thu, 29 Jun 2017 02:13:29 GMT any randomness seed: 0.4070123094134033
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| 19 | ```
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| 20 |
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| 21 | ## Set the seed
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| 22 |
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| 23 | Once a problematic `seed` is determined, it can be provided back to any so that
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| 24 | the generation becomes repeatable.
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| 25 |
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| 26 | ```sh
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| 27 | $ ANY_SEED=0.4070123094134033 mocha --recursive test/unit/
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| 28 | ```
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