Update mocha testing function

Author: scottdj92

index.js

@@ -9,7 +9,7 @@ var ExtractedModule = require("./ExtractedModule");
 var Chunk = require("webpack/lib/Chunk");
 var OrderUndefinedError = require("./OrderUndefinedError");
 var loaderUtils = require("loader-utils");
-var schemaTester = require('./schema/valid');
+var schemaTester = require('./schema/validator');
 
 var NS = fs.realpathSync(__dirname);
 
@@ -105,7 +105,6 @@ function getOrder(a, b) {
 }
 
 function ExtractTextPlugin(options) {
-	schemaTester(options);
 	if(arguments.length > 1) {
 		throw new Error("Breaking change: ExtractTextPlugin now only takes a single argument. Either an options " +
 						"object *or* the name of the result file.\n" +
@@ -120,6 +119,8 @@ function ExtractTextPlugin(options) {
 	}
 	if(isString(options)) {
 		options = { filename: options };
+	} else {
+		schemaTester(options);
 	}
 	this.filename = options.filename;
 	this.id = options.id != null ? options.id : ++nextId;

schema/validator.js

@@ -0,0 +1,12 @@
+var Ajv = require('ajv');
+var ajv = new Ajv({allErrors: true});
+var json = require('./schema.json');
+
+module.exports = function validate(data) {
+	var validSchema = ajv.compile(json);
+	var valid = validSchema(data);
+
+	if(!valid) {
+		throw new Error("Your ExtractTextPlugin config is not correct. Please double check.");
+	}
+}

test/extract.test.js

@@ -10,6 +10,26 @@ describe("ExtractTextPlugin.extract()", function() {
 		});
 	});
 
+	context("json schema validation", function() {
+		it("throws if an incorrect config is passed in", function() {
+			should.throws(function() {
+				ExtractTextPlugin.extract(['style-loader', 'file.css']);
+			});
+		});
+
+		it("does not throw if a correct config object is passed in", function() {
+			should.doesNotThrow(function() {
+				ExtractTextPlugin.extract({loader: 'css-loader'});
+			});
+		});
+
+		it("does not throw if a filename is specified", function() {
+			should.doesNotThrow(function() {
+				ExtractTextPlugin.extract("file.css");
+			});
+		});
+	});
+
 	context("specifying loader", function() {
 		it("accepts a loader string", function() {
 			ExtractTextPlugin.extract("css-loader").should.deepEqual([