Remove mocha from hardhat-core

[fvictorio]

We want to remove Mocha from hardhat-core. Users should be able to just install and require a plugin (e.g., @nomiclabs/hardhat-mocha) to have the same functionality that they have now.

Since this is a breaking change, we should do it in two phases.

Phase 1: create plugin and add warning

First we should create and publish that plugin, and change the default test task so that it prints a warning after finishing, saying something like: "The default test task is deprecated, please install and use <plugin-name>"

The plugin would override the test task with the same implementation we have now, and without calling runSuper. That way the behavior wouldn't change, but the warning wouldn't be shown.

Phase 2: remove default implementation and throw an error in the test task

After some time (~2 months) we should remove the dependency on mocha and change the default task to just throw an error indicating users to install hardhat-mocha.

Other considerations

I'm not sure what this means for plugins. For example, I think this would break hardhat-gas-reporter if the plugin is required before the hardhat-mocha plugin.

[alcuadrado]

I'm not sure what this means for plugins. For example, I think this would break hardhat-gas-reporter if the plugin is required before the hardhat-mocha plugin.

We need to let plugin authors know that they must explicitly depend on hardhat-mocha if they were implicitly depending on mocha. This should be done during Phase 1

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[fvictorio]

Relevant.

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This issue was marked as stale because it didn't have any activity in the last 30 days. If you think it's still relevant, please leave a comment indicating so. Otherwise, it will be closed in 7 days.

[github-actions]

This issue was closed because it has been stalled for 7 days with no activity.

[niconiahi]

it would be a really nice feature to have. I would like to integrate with my already in use vitest package