bugfix: env min/max input validation

[xninjax]

Description

This was originally going to be a bug report, instead submitting PR with possible solution.

ISSUE
When supplying only one of a min/max pair from .env, undesirable results can occur in code.
I discovered this when setting only PAGE_SLEEP_MIN="60000" ... resulting in the page hits to occur more often than 60sec.

Why?
The culprit
getSleepTime() { return config.browser.minSleep + (Math.random() * (config.browser.maxSleep - config.browser.minSleep)); }

Since PAGE_SLEEP_MAX defaults to "10000"

getSleepTime() { return 60000 + (Math.random() * (10000 - 60000)); }

We're applying a negative number to the Math.random result ☝️ . Thus subtracting from the original 60sec delay.

Possible solution

... Math.random() * Math.abs(config.browser.maxSleep - config.browser.minSleep)) ...

Math.abs... is one possible fix, but doesn't really get the job done properly IMO. Would still need to think about how to address this for PAGE_BACKOFF_MIN/MAX. And again for all future min/max pairs.

Instead, I propose MIN/MAX input validation (subject of this PR).

function envOrNumberMinMax
  Returns environment variable, given number, or default number,
  while handling .env input errors for a Min/Max pair.
  .env errors handled:
  - Min/Max swapped (Min larger than Max, Max smaller than Min)
  - Min larger than default Max when no Max defined
  - Max smaller than default Min when no Min defined

Testing

Input validation applied...
With PAGE_SLEEP_MIN="60000" entered as before, and appling input validation, results are now as expected.

Other Scenario's

The following works because input validation swaps min/max first (not well illustrated, but was verified)

[xninjax]

linter is not liking the single line 'if' statements, and I knew it would complain, since local checks warned me too.

I can expand, but will look more of a mess 🤷‍♂️

[jef]

getSleepTime() { return 60000 + (Math.random() * (10000 - 60000)); }

Ahhhhhh... Good find! Definitely want to bring this in.

Yeah, if you don't mind running npm run lint:fix. Keeps it consistent.

Thanks!

[xninjax]

All expanded so linter is happy 😄

[jef]

Great! Thank you very much for doing this. I really appreciate it. This will hopefully clear up some issues.