Add system requirements to the engines field in package (#406)

package.json

@@ -7,7 +7,9 @@
 	"bin": "source/cli.js",
 	"engines": {
 		"node": ">=8",
-		"npm": ">=6.8.0"
+		"npm": ">=6.8.0",
+		"git": ">=2.11.0",
+		"yarn": ">=1.7.0"
 	},
 	"scripts": {
 		"test": "xo && FORCE_HYPERLINK=1 ava"

source/git-util.js

@@ -3,6 +3,8 @@ const execa = require('execa');
 const escapeStringRegexp = require('escape-string-regexp');
 const version = require('./version');
 
+const {versionSatisfiesRequirement} = version;
+
 exports.latestTag = () => execa.stdout('git', ['describe', '--abbrev=0', '--tags']);
 
 const firstCommit = () => execa.stdout('git', ['rev-list', '--max-parents=0', 'HEAD']);
@@ -128,9 +130,6 @@ const gitVersion = async () => {
 
 exports.verifyRecentGitVersion = async () => {
 	const installedVersion = await gitVersion();
-	const minVersion = '2.11.0';
 
-	if (!version(minVersion).isGreaterThanOrEqualTo(installedVersion)) {
-		throw new Error('Please upgrade to git@2.11.0 or newer.');
-	}
+	versionSatisfiesRequirement('git', installedVersion);
 };

source/npm/util.js

@@ -5,6 +5,7 @@ const ow = require('ow');
 const npmName = require('npm-name');
 const version = require('../version');
 
+const {versionSatisfiesRequirement} = version;
 exports.checkConnection = () => pTimeout(
 	(async () => {
 		try {
@@ -85,8 +86,5 @@ exports.version = () => execa.stdout('npm', ['--version']);
 
 exports.verifyRecentNpmVersion = async () => {
 	const npmVersion = await exports.version();
-
-	if (version(npmVersion).satisfies('<6.8.0')) {
-		throw new Error('Please upgrade to npm@6.8.0 or newer');
-	}
+	versionSatisfiesRequirement('npm', npmVersion);
 };

source/prerequisite-tasks.js

@@ -6,6 +6,8 @@ const git = require('./git-util');
 const npm = require('./npm/util');
 const {getTagVersionPrefix} = require('./util');
 
+const {versionSatisfiesRequirement} = version;
+
 module.exports = (input, pkg, options) => {
 	const isExternalRegistry = npm.isExternalRegistry(pkg);
 	let newVersion = null;
@@ -25,10 +27,7 @@ module.exports = (input, pkg, options) => {
 			enabled: () => options.yarn === true,
 			task: async () => {
 				const yarnVersion = await execa.stdout('yarn', ['--version']);
-
-				if (version(yarnVersion).satisfies('<1.7.0')) {
-					throw new Error('Please upgrade to yarn@1.7.0 or newer');
-				}
+				versionSatisfiesRequirement('yarn', yarnVersion);
 			}
 		},
 		{

source/version.js

@@ -57,3 +57,10 @@ module.exports.validate = version => {
 		throw new Error('Version should be a valid semver version.');
 	}
 };
+
+module.exports.versionSatisfiesRequirement = (dependency, version) => {
+	const depRange = require('../package.json').engines[dependency];
+	if (!module.exports(version).satisfies(depRange)) {
+		throw new Error(`Please upgrade to ${dependency}${depRange}`);
+	}
+};