Build: Migrate middleware-mockserver to modern JS

The `test/middleware-mockserver.js` file used to have the same ESLint
settings applied as other test files that are directly run in tested
browsers. Now it shares settings of other Node.js files.

The file is now also written using modern JS, leveraging ES2018.

Closes gh-5196

2 files changed, 80 insertions, 60 deletions

diff --git a/test/.eslintrc.json b/test/.eslintrc.json
index 0048810f6..b95c113d6 100644
--- a/test/.eslintrc.json
+++ b/test/.eslintrc.json
@@ -60,6 +60,14 @@
 	"overrides": [
 		{
 			"files": [
+				"middleware-mockserver.js"
+			],
+
+			"extends": "../.eslintrc-node.json"
+		},
+
+		{
+			"files": [
 				"data/core/jquery-iterability-transpiled-es6.js",
 				"data/testinit-jsdom.js"
 			],
diff --git a/test/middleware-mockserver.js b/test/middleware-mockserver.js
index ea6a5d2b0..2b6970226 100644
--- a/test/middleware-mockserver.js
+++ b/test/middleware-mockserver.js
@@ -1,9 +1,11 @@
-/* eslint-env node */
-var url = require( "url" );
-var fs = require( "fs" );
-var getRawBody = require( "raw-body" );
+"use strict";
+
+const url = require( "url" );
+const fs = require( "fs" );
+const getRawBody = require( "raw-body" );
+
+let cspLog = "";
 
-var cspLog = "";
 /**
  * Keep in sync with /test/mock.php
  */
@@ -11,7 +13,7 @@ function cleanCallback( callback ) {
 	return callback.replace( /[^a-z0-9_]/gi, "" );
 }
 
-var mocks = {
+const mocks = {
 	contentType: function( req, resp ) {
 		resp.writeHead( 200, {
 			"content-type": req.query.contentType
@@ -19,7 +21,7 @@ var mocks = {
 		resp.end( req.query.response );
 	},
 	wait: function( req, resp ) {
-		var wait = Number( req.query.wait ) * 1000;
+		const wait = Number( req.query.wait ) * 1000;
 		setTimeout( function() {
 			if ( req.query.script ) {
 				resp.writeHead( 200, { "content-type": "text/javascript" } );
@@ -44,7 +46,7 @@ var mocks = {
 		}, next );
 	},
 	xml: function( req, resp, next ) {
-		var content = "<math><calculation>5-2</calculation><result>3</result></math>";
+		const content = "<math><calculation>5-2</calculation><result>3</result></math>";
 		resp.writeHead( 200, { "content-type": "text/xml" } );
 
 		if ( req.query.cal === "5-2" ) {
@@ -59,7 +61,7 @@ var mocks = {
 			}
 		}, next );
 	},
-	atom: function( req, resp, next ) {
+	atom: function( _req, resp ) {
 		resp.writeHead( 200, { "content-type": "atom+xml" } );
 		resp.end( "<root><element /></root>" );
 	},
@@ -77,14 +79,14 @@ var mocks = {
 		}
 
 		if ( req.query.callback ) {
-			resp.end( cleanCallback( req.query.callback ) + "(" + JSON.stringify( {
+			resp.end( `${ cleanCallback( req.query.callback ) }(${ JSON.stringify( {
 				headers: req.headers
-			} ) + ")" );
+			} ) })` );
 		} else {
 			resp.end( "QUnit.assert.ok( true, \"mock executed\" );" );
 		}
 	},
-	testbar: function( req, resp ) {
+	testbar: function( _req, resp ) {
 		resp.writeHead( 200 );
 		resp.end(
 			"this.testBar = 'bar'; " +
@@ -110,7 +112,7 @@ var mocks = {
 		}
 	},
 	jsonp: function( req, resp, next ) {
-		var callback;
+		let callback;
 		if ( Array.isArray( req.query.callback ) ) {
 			callback = Promise.resolve( req.query.callback[ req.query.callback.length - 1 ] );
 		} else if ( req.query.callback ) {
@@ -122,7 +124,7 @@ var mocks = {
 				return body.trim().replace( "callback=", "" );
 			} );
 		}
-		var json = req.query.array ?
+		const json = req.query.array ?
 			JSON.stringify(
 				[ { name: "John", age: 21 }, { name: "Peter", age: 25 } ]
 			) :
@@ -130,14 +132,14 @@ var mocks = {
 				{ data: { lang: "en", length: 25 } }
 			);
 		callback.then( function( cb ) {
-			resp.end( cleanCallback( cb ) + "(" + json + ")" );
+			resp.end( `${ cleanCallback( cb ) }(${ json })` );
 		}, next );
 	},
 	xmlOverJsonp: function( req, resp ) {
-		var callback = req.query.callback;
-		var body = fs.readFileSync( __dirname + "/data/with_fries.xml" ).toString();
+		const callback = req.query.callback;
+		const body = fs.readFileSync( `${ __dirname }/data/with_fries.xml` ).toString();
 		resp.writeHead( 200 );
-		resp.end( cleanCallback( callback ) + "(" + JSON.stringify( body ) + ")\n" );
+		resp.end( `${ cleanCallback( callback ) }(${ JSON.stringify( body ) })\n` );
 	},
 	error: function( req, resp ) {
 		if ( req.query.json ) {
@@ -159,7 +161,7 @@ var mocks = {
 		} );
 		req.query.keys.split( "|" ).forEach( function( key ) {
 			if ( key.toLowerCase() in req.headers ) {
-				resp.write( key + ": " + req.headers[ key.toLowerCase() ] + "\n" );
+				resp.write( `${ key }: ${ req.headers[ key.toLowerCase() ] }\n` );
 			}
 		} );
 		resp.end();
@@ -177,16 +179,16 @@ var mocks = {
 	},
 	echoHtml: function( req, resp, next ) {
 		resp.writeHead( 200, { "Content-Type": "text/html" } );
-		resp.write( "<div id='method'>" + req.method + "</div>" );
-		resp.write( "<div id='query'>" + req.parsed.search.slice( 1 ) + "</div>" );
+		resp.write( `<div id='method'>${ req.method }</div>` );
+		resp.write( `<div id='query'>${ req.parsed.search.slice( 1 ) }</div>` );
 		getBody( req ).then( function( body ) {
-			resp.write( "<div id='data'>" + body + "</div>" );
+			resp.write( `<div id='data'>${ body }</div>` );
 			resp.end( body );
 		}, next );
 	},
 	etag: function( req, resp ) {
-		var hash = Number( req.query.ts ).toString( 36 );
-		var etag = "W/\"" + hash + "\"";
+		const hash = Number( req.query.ts ).toString( 36 );
+		const etag = `W/"${ hash }"`;
 		if ( req.headers[ "if-none-match" ] === etag ) {
 			resp.writeHead( 304 );
 			resp.end();
@@ -197,8 +199,8 @@ var mocks = {
 		} );
 		resp.end();
 	},
-	ims: function( req, resp, next ) {
-		var ts = req.query.ts;
+	ims: function( req, resp ) {
+		const ts = req.query.ts;
 		if ( req.headers[ "if-modified-since" ] === ts ) {
 			resp.writeHead( 304 );
 			resp.end();
@@ -209,67 +211,75 @@ var mocks = {
 		} );
 		resp.end();
 	},
-	status: function( req, resp, next ) {
+	status: function( req, resp ) {
 		resp.writeHead( Number( req.query.code ) );
 		resp.end();
 	},
 	testHTML: function( req, resp ) {
 		resp.writeHead( 200, { "Content-Type": "text/html" } );
-		var body = fs.readFileSync( __dirname + "/data/test.include.html" ).toString();
-		body = body.replace( /{{baseURL}}/g, req.query.baseURL );
+		const body = fs
+			.readFileSync( `${ __dirname }/data/test.include.html` )
+			.toString()
+			.replace( /{{baseURL}}/g, req.query.baseURL );
 		resp.end( body );
 	},
-	cspFrame: function( req, resp ) {
+	cspFrame: function( _req, resp ) {
 		resp.writeHead( 200, {
 			"Content-Type": "text/html",
-			"Content-Security-Policy": "default-src 'self'; require-trusted-types-for 'script'; report-uri /base/test/data/mock.php?action=cspLog"
+			"Content-Security-Policy": "default-src 'self'; require-trusted-types-for 'script'; " +
+				"report-uri /base/test/data/mock.php?action=cspLog"
 		} );
-		var body = fs.readFileSync( __dirname + "/data/csp.include.html" ).toString();
+		const body = fs.readFileSync( `${ __dirname }/data/csp.include.html` ).toString();
 		resp.end( body );
 	},
 	cspNonce: function( req, resp ) {
-		var testParam = req.query.test ? "-" + req.query.test : "";
+		const testParam = req.query.test ? `-${ req.query.test }` : "";
 		resp.writeHead( 200, {
 			"Content-Type": "text/html",
-			"Content-Security-Policy": "script-src 'nonce-jquery+hardcoded+nonce'; report-uri /base/test/data/mock.php?action=cspLog"
+			"Content-Security-Policy": "script-src 'nonce-jquery+hardcoded+nonce'; " +
+				"report-uri /base/test/data/mock.php?action=cspLog"
 		} );
-		var body = fs.readFileSync(
-			__dirname + "/data/csp-nonce" + testParam + ".html" ).toString();
+		const body = fs.readFileSync(
+			`${ __dirname }/data/csp-nonce${ testParam }.html` ).toString();
 		resp.end( body );
 	},
-	cspAjaxScript: function( req, resp ) {
+	cspAjaxScript: function( _req, resp ) {
 		resp.writeHead( 200, {
 			"Content-Type": "text/html",
-			"Content-Security-Policy": "script-src 'self'; report-uri /base/test/data/mock.php?action=cspLog"
+			"Content-Security-Policy": "script-src 'self'; " +
+				"report-uri /base/test/data/mock.php?action=cspLog"
 		} );
-		var body = fs.readFileSync(
-			__dirname + "/data/csp-ajax-script.html" ).toString();
+		const body = fs.readFileSync(
+			`${ __dirname }/data/csp-ajax-script.html` ).toString();
 		resp.end( body );
 	},
-	cspLog: function( req, resp ) {
+	cspLog: function( _req, resp ) {
 		cspLog = "error";
 		resp.writeHead( 200 );
 		resp.end();
 	},
-	cspClean: function( req, resp ) {
+	cspClean: function( _req, resp ) {
 		cspLog = "";
 		resp.writeHead( 200 );
 		resp.end();
 	},
-	trustedHtml: function( req, resp ) {
+	trustedHtml: function( _req, resp ) {
 		resp.writeHead( 200, {
 			"Content-Type": "text/html",
-			"Content-Security-Policy": "require-trusted-types-for 'script'; report-uri /base/test/data/mock.php?action=cspLog"
+			"Content-Security-Policy": "require-trusted-types-for 'script'; " +
+				"report-uri /base/test/data/mock.php?action=cspLog"
 		} );
-		var body = fs.readFileSync( __dirname + "/data/trusted-html.html" ).toString();
+		const body = fs.readFileSync( `${ __dirname }/data/trusted-html.html` ).toString();
 		resp.end( body );
 	},
-	trustedTypesAttributes: function( req, resp ) {
+	trustedTypesAttributes: function( _req, resp ) {
 		resp.writeHead( 200, {
 			"Content-Type": "text/html",
-			"Content-Security-Policy": "require-trusted-types-for 'script'; report-uri /base/test/data/mock.php?action=cspLog"
+			"Content-Security-Policy": "require-trusted-types-for 'script'; " +
+				"report-uri /base/test/data/mock.php?action=cspLog"
 		} );
-		var body = fs.readFileSync( __dirname + "/data/trusted-types-attributes.html" ).toString();
+		const body = fs.readFileSync(
+			`${ __dirname }/data/trusted-types-attributes.html` ).toString();
 		resp.end( body );
 	},
 	errorWithScript: function( req, resp ) {
@@ -279,14 +289,14 @@ var mocks = {
 			resp.writeHead( 404, { "Content-Type": "text/html; charset=UTF-8" } );
 		}
 		if ( req.query.callback ) {
-			resp.end( cleanCallback( req.query.callback ) +
-				"( {\"status\": 404, \"msg\": \"Not Found\"} )" );
+			resp.end( `${ cleanCallback( req.query.callback )
+				}( {"status": 404, "msg": "Not Found"} )` );
 		} else {
 			resp.end( "QUnit.assert.ok( false, \"Mock return erroneously executed\" );" );
 		}
 	}
 };
-var handlers = {
+const handlers = {
 	"test/data/mock.php": function( req, resp, next ) {
 		if ( !mocks[ req.query.action ] ) {
 			resp.writeHead( 400 );
@@ -296,11 +306,11 @@ var handlers = {
 		}
 		mocks[ req.query.action ]( req, resp, next );
 	},
-	"test/data/support/csp.log": function( req, resp ) {
+	"test/data/support/csp.log": function( _req, resp ) {
 		resp.writeHead( 200 );
 		resp.end( cspLog );
 	},
-	"test/data/404.txt": function( req, resp ) {
+	"test/data/404.txt": function( _req, resp ) {
 		resp.writeHead( 404 );
 		resp.end( "" );
 	}
@@ -315,21 +325,23 @@ var handlers = {
  * Express versions of these (e.g. no req.path, req.query, resp.set).
  */
 function MockserverMiddlewareFactory() {
+
 	/**
 	 * @param {http.IncomingMessage} req
 	 * @param {http.ServerResponse} resp
 	 * @param {Function} next Continue request handling
 	 */
 	return function( req, resp, next ) {
-		var parsed = url.parse( req.url, /* parseQuery */ true ),
-			path = parsed.pathname.replace( /^\/base\//, "" ),
-			query = parsed.query,
-			subReq = Object.assign( Object.create( req ), {
-				query: query,
-				parsed: parsed
-			} );
+		const parsed = url.parse( req.url, /* parseQuery */ true );
+		let path = parsed.pathname.replace( /^\/base\//, "" );
+		const query = parsed.query;
+		const subReq = Object.assign( Object.create( req ), {
+			query: query,
+			parsed: parsed
+		} );
 
 		if ( /^test\/data\/mock.php\//.test( path ) ) {
+
 			// Support REST-like Apache PathInfo
 			path = "test\/data\/mock.php";
 		}