remove engines.npm from package.json

[pabigot]

Prerequisites

• Checked that your issue isn't already filed by cross referencing issues with the common mistake label
• Checked next-gen ES issues and syntax problems by using the same environment and/or transpiler configuration without Mocha to ensure it isn't just a feature that actually isn't supported in the environment in question or a bug in your code.
• 'Smoke tested' the code to be tested by running it outside the real test suite to get a better sense of whether the problem is in the code under test, your usage of Mocha, or Mocha itself
• Ensured that there is no discrepancy between the locally and globally installed versions of Mocha. You can find them with:
  node node_modules/.bin/mocha --version(Local) and mocha --version(Global). We recommend avoiding the use of globally installed Mocha.

Description

Node 4.0 introduced an engine dependency on npm >= 2.15.11. The blog post says this is because that version shipped with Node.js v4.0.0.

This is incorrect. Nodejs v4.0.0 shipped with npm 2.14.2. Nodejs v4.5.0, which I have to use, shipped with 2.15.9.

It is true that the current Nodejs 4 (v4.8.4 at time of writing) does use 2.15.11, but that update wasn't done until v4.6.2.

Please consider reducing the dependency to 2.14.2, if your intent is to support all Nodejs 4 releases.

Steps to Reproduce

Expected behavior: Installation of mocha 4.0.1 under nodejs 4.5.0 emits no diagnostics.

Actual behavior:

npm WARN engine [email protected]: wanted: {"node":">= 4.0.0","npm":">= 2.15.11"} (current: {"node":"4.5.0","npm":"2.15.9"})

Reproduces how often: Every time

Versions

Additional Information

[boneskull]

@pabigot Are you using AWS Lambda?

[boneskull]

@pabigot Also, is there anything other than a warning? In other words, is this the only "symptom"?

[boneskull]

See #3149 as well

[boneskull]

I'm not entirely sure what the intent should be. Only the latest v4.x is maintained, so perhaps the engines field should be updated instead.

[boneskull]

or we could add 4.0.0 to the build matrix...

[pabigot]

No, I'm not using lambda. It is a warning, but that warning suggests the claim of supporting >=4 (rather than >=4.6.2) is not justified: if I saw this in a production dependency I'd be much more concerned that it reflected a real failure to support. Until action occurs on #3149 my preferred path is that the npm engine dependency be reduced to match the documented behavior and 4.0.0 be added to the build matrix.

I don't think it makes sense only support the latest release in any LTS series. You'd spend a lot of time updating dependencies and annoying users who don't want to update their infrastructure every couple weeks.

[boneskull]

From what I understand, npm's behavior when the engines field is violated is a warning, but Yarn will actually error and refuse to install.

Given that a version of npm which fails to install Mocha is by definition incompatible, one can find that out rather directly by attempting to install Mocha with said incompatible version. 😄

I am proposing removal of the engines.npm field, since we can't be certain what it does or what value it provides in any given situation.

[boneskull]

@pabigot #3154

[pabigot]

@boneskull I don't see any issues with the solution in #3154.

[boneskull]

@pabigot #3154 is the fix to remove the field and thus the warning.