Build: Make dev mode work in Karma again, serve source files from disk

PR gh-4550 added support for running ES modules & AMD tests via Karma. This
required reading the `esmodules` & `amd` props from both `QUnit.config` &
`QUnit.urlParams`. By picking these two properties manually, the `dev` one
stopped being respected while ones handled directly by QUnit were fine (like
`hidepassed`). Instead of maintaining the full list of options, the code now
iterates over QUnit URL config and handles the fallbacks in a more generic way.

Apart from that, all jQuery source & test files are now read directly from disk
instead of being cached by Karma so that one can run `grunt karma:chrome-debug`
& work on a fix without restarting that Karma run after each change. A similar
effect could have been achieved by setting `autoWatch` to `true` but then the
main Karma page runs tests in an iframe by default when
`grunt karma:chrome-debug` is run instead of relying on the current debug flow.

Closes gh-4574
Ref gh-4550

Gruntfile.js

@@ -158,14 +158,31 @@ module.exports = function( grunt ) {
 
 					"test/jquery.js",
 
-					{ pattern: "dist/jquery.*", included: false, served: true },
-					{ pattern: "src/**", type: "module", included: false, served: true },
-					{ pattern: "amd/**", included: false, served: true },
+					{
+						pattern: "dist/jquery.*",
+						included: false,
+						served: true,
+						nocache: true
+					},
+					{
+						pattern: "src/**",
+						type: "module",
+						included: false,
+						served: true,
+						nocache: true
+					},
+					{
+						pattern: "amd/**",
+						included: false,
+						served: true,
+						nocache: true
+					},
 					{ pattern: "node_modules/**", included: false, served: true },
 					{
 						pattern: "test/**/*.@(js|css|jpg|html|xml|svg)",
 						included: false,
-						served: true
+						served: true,
+						nocache: true
 					}
 				],
 				reporters: [ "dots" ],

test/jquery.js

@@ -2,29 +2,34 @@
 ( function() {
 	/* global loadTests: false */
 
-	var dynamicImportSource,
+	var dynamicImportSource, config, src,
 		FILEPATH = "/test/jquery.js",
 		activeScript = [].slice.call( document.getElementsByTagName( "script" ), -1 )[ 0 ],
 		parentUrl = activeScript && activeScript.src ?
 			activeScript.src.replace( /[?#].*/, "" ) + FILEPATH.replace( /[^/]+/g, ".." ) + "/" :
 			"../",
 		QUnit = window.QUnit,
-		require = window.require,
+		require = window.require;
+
+	function getQUnitConfig() {
+		var config = Object.create( null );
 
 		// Default to unminified jQuery for directly-opened iframes
-		config = QUnit ?
+		if ( !QUnit ) {
+			config.dev = true;
+		} else {
 
 			// QUnit.config is populated from QUnit.urlParams but only at the beginning
 			// of the test run. We need to read both.
-			{
-				esmodules: !!( QUnit.config.esmodules || QUnit.urlParams.esmodules ),
-				amd: !!( QUnit.config.amd || QUnit.urlParams.amd )
-			} :
+			QUnit.config.urlConfig.forEach( function( entry ) {
+				config[ entry.id ] = QUnit.config[ entry.id ] != null ?
+					QUnit.config[ entry.id ] :
+					QUnit.urlParams[ entry.id ];
+			} );
+		}
 
-			{ dev: true },
-		src = config.dev ?
-			"dist/jquery.js" :
-			"dist/jquery.min.js";
+		return config;
+	}
 
 	// Define configuration parameters controlling how jQuery is loaded
 	if ( QUnit ) {
@@ -43,6 +48,12 @@
 		} );
 	}
 
+	config = getQUnitConfig();
+
+	src = config.dev ?
+		"dist/jquery.js" :
+		"dist/jquery.min.js";
+
 	// Honor ES modules loading on the main window (detected by seeing QUnit on it).
 	// This doesn't apply to iframes because they synchronously expect jQuery to be there.
 	if ( config.esmodules && QUnit ) {