feat: Initial implementation

.gitignore

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+*.tgz
+node_modules
+coverage
+.nyc_output
+package

.npmignore

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+*.tgz
+.taprc
+.travis.yml
+.nyc_output/
+nyc.config.js
+fixtures/
+test/

.npmrc

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+package-lock=false

.taprc

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+esm: false
+100: true
+timeout: 60000
+nyc-arg:
+  - "--all"

.travis.yml

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+os:
+  - windows
+  - linux
+  - osx
+
+language: node_js
+
+node_js:
+  - 12
+  - 10
+  - 8

LICENSE

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+MIT License
+
+Copyright (c) 2019 CFWare, LLC
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# process-on-spawn
+
+[![Travis CI][travis-image]][travis-url]
+[![Greenkeeper badge][gk-image]](https://greenkeeper.io/)
+[![NPM Version][npm-image]][npm-url]
+[![NPM Downloads][downloads-image]][downloads-url]
+[![MIT][license-image]](LICENSE)
+
+Execute callbacks when child processes are spawned.
+
+## Usage
+
+```js
+'use strict';
+
+const processOnSpawn = require('process-on-spawn');
+processOnSpawn.addListener(opts => {
+  opts.env.CHILD_VARIABLE = 'value';
+});
+```
+
+### listener(opts)
+
+* `options` \<[Object]\>
+  * `execPath` \<[string]\> The command to run.
+  * `args` \<[string\[\]][string]\> Arguments of the child process.
+  * `cwd` \<[string]\> Current working directory of the child process.
+  * `detached` \<[boolean]\> The child will be prepared to run independently of its parent process.
+  * `uid` \<[number]\> The user identity to be used by the child.
+  * `gid` \<[number]\> The group identity to be used by the child.
+  * `windowsVerbatimArguments` \<[boolean]\> No quoting or escaping of arguments will be done on Windows.
+  * `windowsHide` \<[boolean]\> The subprocess console window that would normally be created on Windows systems will be hidden.
+
+All properties except `env` are read-only.
+
+### processOnSpawn.addListener(listener)
+
+Add a listener to be called after any listeners already attached.
+
+### processOnSpawn.prependListener(listener)
+
+Insert a listener to be called before any listeners already attached.
+
+### processOnSpawn.removeListener(listener)
+
+Remove the specified listener.  If the listener was added multiple times only
+the first is removed.
+
+### processOnSpawn.removeAllListeners()
+
+Remove all attached listeners.
+
+[npm-image]: https://img.shields.io/npm/v/process-on-spawn.svg
+[npm-url]: https://npmjs.org/package/process-on-spawn
+[travis-image]: https://travis-ci.org/cfware/process-on-spawn.svg?branch=master
+[travis-url]: https://travis-ci.org/cfware/process-on-spawn
+[gk-image]: https://badges.greenkeeper.io/cfware/process-on-spawn.svg
+[downloads-image]: https://img.shields.io/npm/dm/process-on-spawn.svg
+[downloads-url]: https://npmjs.org/package/process-on-spawn
+[license-image]: https://img.shields.io/npm/l/process-on-spawn.svg
+[Object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
+[string]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type
+[boolean]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type
+[number]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type

fixtures/dump-env.js

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+#!/usr/bin/env node
+'use strict';
+
+const env = {...process.env};
+for (const key of Object.keys(env)) {
+	if (/^path$/i.test(key)) {
+		delete env[key];
+	}
+}
+
+console.log(JSON.stringify(env));

index.js

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+'use strict';
+
+/* Drop this dependency once node.js 12 is required. */
+const fromEntries = require('fromentries');
+
+const state = getState(1);
+
+function getState(version) {
+	const stateId = Symbol.for('process-on-spawn@*:singletonId');
+
+	/* istanbul ignore next: cannot cover this once nyc depends on this module */
+	if (stateId in global === false) {
+		/* Hopefully version and unwrap forward compatibility is never actually needed */
+		Object.defineProperty(global, stateId, {
+			writable: true,
+			value: {
+				version,
+				listeners: [],
+				unwrap: wrapSpawnFunctions()
+			}
+		});
+	}
+
+	return global[stateId];
+}
+
+function wrappedSpawnFunction(fn) {
+	return function (options) {
+		let env = fromEntries(
+			options.envPairs.map(nvp => nvp.split(/^([^=]*)=/).slice(1))
+		);
+
+		const opts = Object.create(null, {
+			env: {
+				enumerable: true,
+				get() {
+					return env;
+				},
+				set(value) {
+					if (!value || typeof value !== 'object') {
+						throw new TypeError('env must be an object');
+					}
+
+					env = value;
+				}
+			},
+			cwd: {
+				enumerable: true,
+				get() {
+					return options.cwd || process.cwd();
+				}
+			}
+		});
+
+		const args = [...options.args];
+		Object.freeze(args);
+		Object.assign(opts, {
+			execPath: options.file,
+			args,
+			detached: Boolean(options.detached),
+			uid: options.uid,
+			gid: options.gid,
+			windowsVerbatimArguments: Boolean(options.windowsVerbatimArguments),
+			windowsHide: Boolean(options.windowsHide)
+		});
+		Object.freeze(opts);
+
+		state.listeners.forEach(listener => {
+			listener(opts);
+		});
+
+		options.envPairs = Object.entries(opts.env).map(([name, value]) => `${name}=${value}`);
+
+		return fn.call(this, options);
+	};
+}
+
+function wrapSpawnFunctions() {
+	const {ChildProcess} = require('child_process');
+
+	/* eslint-disable-next-line node/no-deprecated-api */
+	const spawnSyncBinding = process.binding('spawn_sync');
+	const originalSync = spawnSyncBinding.spawn;
+	const originalAsync = ChildProcess.prototype.spawn;
+
+	spawnSyncBinding.spawn = wrappedSpawnFunction(spawnSyncBinding.spawn);
+	ChildProcess.prototype.spawn = wrappedSpawnFunction(ChildProcess.prototype.spawn);
+
+	/* istanbul ignore next: forward compatibility code */
+	return () => {
+		spawnSyncBinding.spawn = originalSync;
+		ChildProcess.prototype.spawn = originalAsync;
+	};
+}
+
+module.exports = {
+	addListener(listener) {
+		state.listeners.push(listener);
+	},
+	prependListener(listener) {
+		state.listeners.unshift(listener);
+	},
+	removeListener(listener) {
+		const idx = state.listeners.indexOf(listener);
+		if (idx !== -1) {
+			state.listeners.splice(idx, 1);
+		}
+	},
+	removeAllListeners() {
+		state.listeners = [];
+	}
+};

nyc.config.js

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+'use strict';
+
+module.exports = {
+	include: ['*.js']
+};

package.json

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+{
+	"name": "process-on-spawn",
+	"version": "1.0.0",
+	"description": "Execute callbacks when child processes are spawned",
+	"scripts": {
+		"release": "standard-version --sign",
+		"pretest": "xo",
+		"test": "tap"
+	},
+	"engines": {
+		"node": ">=8"
+	},
+	"author": "Corey Farrell",
+	"license": "MIT",
+	"repository": {
+		"type": "git",
+		"url": "git+https://github.com/cfware/process-on-spawn.git"
+	},
+	"bugs": {
+		"url": "https://github.com/cfware/process-on-spawn/issues"
+	},
+	"homepage": "https://github.com/cfware/process-on-spawn#readme",
+	"dependencies": {
+		"fromentries": "^1.2.0"
+	},
+	"devDependencies": {
+		"standard-version": "^7.0.0",
+		"tap": "=14.10.2-unbundled",
+		"xo": "^0.25.3"
+	}
+}