Simpler regex while validating encoding string

src/XMLStringifier.coffee

@@ -49,7 +49,7 @@ module.exports = class XMLStringifier
     val
   xmlEncoding: (val) ->
     val = '' + val or ''
-    if not val.match /^[A-Za-z](?:[A-Za-z0-9._-]|-)*$/
+    if not val.match /^[A-Za-z](?:[A-Za-z0-9._-])*$/
       throw new Error "Invalid encoding: " + val
     val
   xmlStandalone: (val) ->

test/issues/encoding.coffee

@@ -0,0 +1,13 @@
+suite 'Tests specific to issues:', ->
+  test 'ReDos', ->
+    eq(
+      xml('root', {encoding: 'UTF-8'}).end()
+      '<?xml version="1.0" encoding="UTF-8"?><root/>'
+    )
+
+    err(
+      () -> xml('root', {encoding: 'A------------------------------------!'})
+      /Invalid encoding: A------------------------------------!/
+    )
+
+

test/mocha.opts

@@ -1,4 +1,4 @@
- --compilers coffee:coffee-script/register
+ --compilers coffee:coffeescript/register
  --require coffee-coverage/register-istanbul
  --require test/common
  --ui tdd