hardhat-watcher

_Automatically run Hardhat actions when files change_

Installation

``bash
npm install hardhat-watcher
`

or

`bash
yarn add hardhat-watcher
`

Import the plugin in your hardhat.config.js:

`js
require('hardhat-watcher')
`

Or if you are using TypeScript, in your hardhat.config.ts:

`ts
import 'hardhat-watcher'
`

Tasks

This plugin adds the _watch_ task to Hardhat:

`bash
npx hardhat watch
`

Configuration

This plugin extends the HardhatUserConfig's object with an optional
watcher field. Every property of watcher is optional.

This is the complete type:

`js
module.exports = {
watcher: {
[key: string]: { // key is the name for the watcherTask
tasks?: (string | { command: string, params?: { [key: string] => any } })[]; // Every task of the hardhat runtime is supported (including other plugins!)
files?: string[]; // Files, directories or glob patterns to watch for changes. (defaults to [config.paths.sources], which itself defaults to the contracts dir)
ignoredFiles?: string[]; // Files, directories or glob patterns that should not be watched.
verbose?: boolean; // Turn on for extra logging
clearOnStart?: boolean; // Turn on to clear the logs (of older task runs) each time before running the task
start?: string; // Run any desirable command each time before the task runs
runOnLaunch?: boolean; // Turn on to run tasks immediately on launch. Be aware, tasks will be run with path parameter "none".
}
}
};
`

Usage

The most basic use case, which is simply compiling your files on change, is accomplished very easily with this config:

`js
module.exports = {
watcher: {
compilation: {
tasks: ['compile'],
},
},
}
`

and subsequently running npx hardhat watch compilation

A bit more involved and showcasing the use of parameters for tasks and defining multiple watcher tasks:

`js
module.exports = {
watcher: {
compilation: {
tasks: ['compile'],
files: ['./contracts'],
ignoredFiles: ['**/.vscode'],
verbose: true,
clearOnStart: true,
start: 'echo Running my compilation task now..',
},
ci: {
tasks: [
'clean',
{ command: 'compile', params: { quiet: true } },
{ command: 'test', params: { noCompile: true, testFiles: ['testfile.ts'] } },
],
},
},
}
`

Run npx hardhat watch ci to clean, compile and test on every file change, or run npx hardhat watch compilation to compile.

$3

Positional arguments are provided in the same way as "normal" arguments (check out the testFiles argument in the example above, it's a positional argument).
In order to find the name of a positional argument, simply run yarn hardhat --help.
This is an example output for the test command:

`
Hardhat version 2.0.2

Usage: hardhat [GLOBAL OPTIONS] test [--no-compile] [...testFiles]

OPTIONS:

--no-compile Don't compile before running this task

POSITIONAL ARGUMENTS:

testFiles An optional list of files to test (default: [])

test: Runs mocha tests

For global options help run: hardhat help
`

$3

The path of the changed file can be inserted into positional arguments using the template parameter {path}. This speeds up iteration in testing, especially if using single test isolation (for example, by using it.only("test") in mocha.)

Example:

`
module.exports = {
watcher: {
test: {
tasks: [{ command: 'test', params: { testFiles: ['{path}'] } }],
files: ['./test/*/'],
verbose: true,
clearOnStart: true,
start: 'echo Running my test task now..',
}
}
}
``