diff --git a/package.json b/package.json
index fc71f364..2af22324 100644
--- a/package.json
+++ b/package.json
@@ -16,8 +16,9 @@
     "mocha": "5.0.0"
   },
   "scripts": {
-    "test": "mocha"
+    "test": "mocha",
+    "acquire": "node test/util/acquire.js"
   },
-  "repository": "git://github.com/darobin/webidl2.js",
+  "repository": "git://github.com/w3c/webidl2.js",
   "main": "index"
 }
diff --git a/test/invalid.js b/test/invalid.js
index 05bc20f3..19bbf006 100644
--- a/test/invalid.js
+++ b/test/invalid.js
@@ -4,38 +4,17 @@
 
 "use strict";
 
-const wp = require("../lib/webidl2");
-const expect = require("expect");
-const pth = require("path");
+const { collect } = require("./util/collect");
 const fs = require("fs");
+const expect = require("expect");
 
 describe("Parses all of the invalid IDLs to check that they blow up correctly", () => {
-  const dir = pth.join(__dirname, "invalid/idl");
-  const skip = {};
-  const idls = fs.readdirSync(dir)
-    .filter(it => (/\.w?idl$/).test(it) && !skip[it])
-    .map(it => pth.join(dir, it));
-
-  for (const idl of idls) {
-    const err = JSON.parse(fs.readFileSync(
-      pth.join(__dirname, "invalid", "json", pth.basename(idl).replace(/\.w?idl/, ".json")),
-      "utf8"
-    ));
-
-    it(`should produce the right error for ${idl}`, () => {
-      let error;
-      try {
-        const ast = wp.parse(fs.readFileSync(idl, "utf8"));
-        console.log(JSON.stringify(ast, null, 4));
-      }
-      catch (e) {
-        error = e;
-      }
-      finally {
-        expect(error).toBeTruthy();
-        expect(error.message).toEqual(err.message);
-        expect(error.line).toEqual(err.line);
-      }
+  for (const test of collect("invalid", { expectError: true })) {
+    it(`should produce the right error for ${test.path}`, () => {
+      const err = test.readJSON();
+      expect(test.error).toBeTruthy();
+      expect(test.error.message).toEqual(err.message);
+      expect(test.error.line).toEqual(err.line);
     });
   }
 });
diff --git a/test/invalid/idl/stringconstants.idl b/test/invalid/idl/stringconstants.widl
similarity index 100%
rename from test/invalid/idl/stringconstants.idl
rename to test/invalid/idl/stringconstants.widl
diff --git a/test/syntax.js b/test/syntax.js
index c7d903bd..05d647ed 100644
--- a/test/syntax.js
+++ b/test/syntax.js
@@ -1,32 +1,14 @@
 "use strict";
 
-const wp = require("../lib/webidl2");
+const { collect } = require("./util/collect");
 const expect = require("expect");
-const pth = require("path");
-const fs = require("fs");
-const jdp = require("jsondiffpatch");
 const debug = true;
 
 describe("Parses all of the IDLs to produce the correct ASTs", () => {
-  const dir = pth.join(__dirname, "syntax/idl");
-  const skip = {}; // use if we have a broken test
-  const idls = fs.readdirSync(dir)
-    .filter(it => (/\.widl$/).test(it) && !skip[it])
-    .map(it => pth.join(dir, it));
-
-  for (const idl of idls) {
-    const json = pth.join(__dirname, "syntax/json", pth.basename(idl).replace(".widl", ".json"));
-
-    it(`should produce the same AST for ${idl}`, () => {
+  for (const test of collect("syntax")) {
+    it(`should produce the same AST for ${test.path}`, () => {
       try {
-        const optFile = pth.join(__dirname, "syntax/opt", pth.basename(json));
-        let opt = undefined;
-        if (fs.existsSync(optFile))
-          opt = JSON.parse(fs.readFileSync(optFile, "utf8"));
-        const diff = jdp.diff(JSON.parse(fs.readFileSync(json, "utf8")),
-          wp.parse(fs.readFileSync(idl, "utf8").replace(/\r\n/g, "\n"), opt));
-        if (diff && debug) console.log(JSON.stringify(diff, null, 4));
-        expect(diff).toBe(undefined);
+        expect(test.diff()).toBeFalsy();
       }
       catch (e) {
         console.log(e.toString());
diff --git a/test/syntax/idl/typedef-union.idl b/test/syntax/idl/typedef-union.widl
similarity index 100%
rename from test/syntax/idl/typedef-union.idl
rename to test/syntax/idl/typedef-union.widl
diff --git a/test/syntax/json/attributes.json b/test/syntax/json/attributes.json
index 86fe9d52..34a36fde 100644
--- a/test/syntax/json/attributes.json
+++ b/test/syntax/json/attributes.json
@@ -24,4 +24,4 @@
         "inheritance": null,
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/constants.json b/test/syntax/json/constants.json
index 75222866..aa5bb274 100644
--- a/test/syntax/json/constants.json
+++ b/test/syntax/json/constants.json
@@ -95,4 +95,4 @@
         "inheritance": null,
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/dictionary-inherits.json b/test/syntax/json/dictionary-inherits.json
index ef30b1ab..48545140 100644
--- a/test/syntax/json/dictionary-inherits.json
+++ b/test/syntax/json/dictionary-inherits.json
@@ -76,4 +76,4 @@
         "inheritance": "PaintOptions",
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/dictionary.json b/test/syntax/json/dictionary.json
index 28494ce4..00d333c6 100644
--- a/test/syntax/json/dictionary.json
+++ b/test/syntax/json/dictionary.json
@@ -124,4 +124,4 @@
         ],
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/documentation-dos.json b/test/syntax/json/documentation-dos.json
index 340e039b..baa0b5a0 100644
--- a/test/syntax/json/documentation-dos.json
+++ b/test/syntax/json/documentation-dos.json
@@ -7,4 +7,4 @@
         "inheritance": null,
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/documentation.json b/test/syntax/json/documentation.json
index 340e039b..baa0b5a0 100644
--- a/test/syntax/json/documentation.json
+++ b/test/syntax/json/documentation.json
@@ -7,4 +7,4 @@
         "inheritance": null,
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/enum.json b/test/syntax/json/enum.json
index 88a608ba..b27eeb7c 100644
--- a/test/syntax/json/enum.json
+++ b/test/syntax/json/enum.json
@@ -3,9 +3,18 @@
         "type": "enum",
         "name": "MealType",
         "values": [
-            { "type": "string", "value": "rice" },
-            { "type": "string", "value": "noodles" },
-            { "type": "string", "value": "other" }
+            {
+                "type": "string",
+                "value": "rice"
+            },
+            {
+                "type": "string",
+                "value": "noodles"
+            },
+            {
+                "type": "string",
+                "value": "other"
+            }
         ],
         "extAttrs": []
     },
@@ -99,9 +108,18 @@
         "type": "enum",
         "name": "AltMealType",
         "values": [
-            { "type": "string", "value": "rice" },
-            { "type": "string", "value": "noodles" },
-            { "type": "string", "value": "other" }
+            {
+                "type": "string",
+                "value": "rice"
+            },
+            {
+                "type": "string",
+                "value": "noodles"
+            },
+            {
+                "type": "string",
+                "value": "other"
+            }
         ],
         "extAttrs": []
     }
diff --git a/test/syntax/json/extended-attributes.json b/test/syntax/json/extended-attributes.json
index b3081bf7..4b6bec14 100644
--- a/test/syntax/json/extended-attributes.json
+++ b/test/syntax/json/extended-attributes.json
@@ -30,140 +30,140 @@
         ]
     },
     {
-      "type": "interface",
-      "name": "IdInterface",
-      "partial": false,
-      "members": [],
-      "inheritance": null,
-      "extAttrs": [
-        {
-          "name": "IntAttr",
-          "arguments": null,
-          "type": "extended-attribute",
-          "rhs": {
-            "type": "integer",
-            "value": "0"
-          }
-        },
-        {
-          "name": "FloatAttr",
-          "arguments": null,
-          "type": "extended-attribute",
-          "rhs": {
-            "type": "float",
-            "value": "3.14"
-          }
-        },
-        {
-          "name": "StringAttr",
-          "arguments": null,
-          "type": "extended-attribute",
-          "rhs": {
-            "type": "string",
-            "value": "\"abc\""
-          }
-        }
-      ]
+        "type": "interface",
+        "name": "IdInterface",
+        "partial": false,
+        "members": [],
+        "inheritance": null,
+        "extAttrs": [
+            {
+                "name": "IntAttr",
+                "arguments": null,
+                "type": "extended-attribute",
+                "rhs": {
+                    "type": "integer",
+                    "value": "0"
+                }
+            },
+            {
+                "name": "FloatAttr",
+                "arguments": null,
+                "type": "extended-attribute",
+                "rhs": {
+                    "type": "float",
+                    "value": "3.14"
+                }
+            },
+            {
+                "name": "StringAttr",
+                "arguments": null,
+                "type": "extended-attribute",
+                "rhs": {
+                    "type": "string",
+                    "value": "\"abc\""
+                }
+            }
+        ]
     },
     {
-      "type": "interface",
-      "name": "Circle",
-      "partial": false,
-      "members": [
-        {
-          "type": "attribute",
-          "static": false,
-          "stringifier": false,
-          "inherit": false,
-          "readonly": false,
-          "idlType": {
-            "sequence": false,
-            "generic": null,
-            "nullable": false,
-            "union": false,
-            "idlType": "double"
-          },
-          "name": "r",
-          "extAttrs": []
-        },
-        {
-          "type": "attribute",
-          "static": false,
-          "stringifier": false,
-          "inherit": false,
-          "readonly": false,
-          "idlType": {
-            "sequence": false,
-            "generic": null,
-            "nullable": false,
-            "union": false,
-            "idlType": "double"
-          },
-          "name": "cx",
-          "extAttrs": []
-        },
-        {
-          "type": "attribute",
-          "static": false,
-          "stringifier": false,
-          "inherit": false,
-          "readonly": false,
-          "idlType": {
-            "sequence": false,
-            "generic": null,
-            "nullable": false,
-            "union": false,
-            "idlType": "double"
-          },
-          "name": "cy",
-          "extAttrs": []
-        },
-        {
-          "type": "attribute",
-          "static": false,
-          "stringifier": false,
-          "inherit": false,
-          "readonly": true,
-          "idlType": {
-            "sequence": false,
-            "generic": null,
-            "nullable": false,
-            "union": false,
-            "idlType": "double"
-          },
-          "name": "circumference",
-          "extAttrs": []
-        }
-      ],
-      "inheritance": null,
-      "extAttrs": [
-        {
-          "name": "Constructor",
-          "arguments": null,
-          "type": "extended-attribute",
-          "rhs": null
-        },
-        {
-          "name": "Constructor",
-          "arguments": [
+        "type": "interface",
+        "name": "Circle",
+        "partial": false,
+        "members": [
+            {
+                "type": "attribute",
+                "static": false,
+                "stringifier": false,
+                "inherit": false,
+                "readonly": false,
+                "idlType": {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "double"
+                },
+                "name": "r",
+                "extAttrs": []
+            },
+            {
+                "type": "attribute",
+                "static": false,
+                "stringifier": false,
+                "inherit": false,
+                "readonly": false,
+                "idlType": {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "double"
+                },
+                "name": "cx",
+                "extAttrs": []
+            },
+            {
+                "type": "attribute",
+                "static": false,
+                "stringifier": false,
+                "inherit": false,
+                "readonly": false,
+                "idlType": {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "double"
+                },
+                "name": "cy",
+                "extAttrs": []
+            },
+            {
+                "type": "attribute",
+                "static": false,
+                "stringifier": false,
+                "inherit": false,
+                "readonly": true,
+                "idlType": {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "double"
+                },
+                "name": "circumference",
+                "extAttrs": []
+            }
+        ],
+        "inheritance": null,
+        "extAttrs": [
             {
-              "optional": false,
-              "variadic": false,
-              "extAttrs": [],
-              "idlType": {
-                "sequence": false,
-                "generic": null,
-                "nullable": false,
-                "union": false,
-                "idlType": "double"
-              },
-              "name": "radius"
+                "name": "Constructor",
+                "arguments": null,
+                "type": "extended-attribute",
+                "rhs": null
+            },
+            {
+                "name": "Constructor",
+                "arguments": [
+                    {
+                        "optional": false,
+                        "variadic": false,
+                        "extAttrs": [],
+                        "idlType": {
+                            "sequence": false,
+                            "generic": null,
+                            "nullable": false,
+                            "union": false,
+                            "idlType": "double"
+                        },
+                        "name": "radius"
+                    }
+                ],
+                "type": "extended-attribute",
+                "rhs": null
             }
-          ],
-          "type": "extended-attribute",
-          "rhs": null
-        }
-      ]
+        ]
     },
     {
         "type": "interface",
diff --git a/test/syntax/json/inherits-getter.json b/test/syntax/json/inherits-getter.json
index ba6bafdf..a37a9851 100644
--- a/test/syntax/json/inherits-getter.json
+++ b/test/syntax/json/inherits-getter.json
@@ -65,4 +65,4 @@
         "inheritance": "Animal",
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/interface-inherits.json b/test/syntax/json/interface-inherits.json
index e78c1cce..51c9aefa 100644
--- a/test/syntax/json/interface-inherits.json
+++ b/test/syntax/json/interface-inherits.json
@@ -74,4 +74,4 @@
         "inheritance": "Animal",
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/iterable.json b/test/syntax/json/iterable.json
index d4b97fba..bb92db89 100644
--- a/test/syntax/json/iterable.json
+++ b/test/syntax/json/iterable.json
@@ -7,7 +7,7 @@
             {
                 "type": "iterable",
                 "idlType": [
-                        {
+                    {
                         "sequence": false,
                         "generic": null,
                         "nullable": false,
@@ -81,4 +81,3 @@
         "extAttrs": []
     }
 ]
-
diff --git a/test/syntax/json/legacyiterable.json b/test/syntax/json/legacyiterable.json
index eca1e6b3..e8a4ed66 100644
--- a/test/syntax/json/legacyiterable.json
+++ b/test/syntax/json/legacyiterable.json
@@ -22,4 +22,3 @@
         "extAttrs": []
     }
 ]
-
diff --git a/test/syntax/json/maplike.json b/test/syntax/json/maplike.json
index 97e76d58..a533838f 100644
--- a/test/syntax/json/maplike.json
+++ b/test/syntax/json/maplike.json
@@ -106,4 +106,3 @@
         "extAttrs": []
     }
 ]
-
diff --git a/test/syntax/json/namedconstructor.json b/test/syntax/json/namedconstructor.json
index cee16306..908bb040 100644
--- a/test/syntax/json/namedconstructor.json
+++ b/test/syntax/json/namedconstructor.json
@@ -40,4 +40,4 @@
             }
         ]
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/nullable.json b/test/syntax/json/nullable.json
index 2c83c3da..dc9cf7f7 100644
--- a/test/syntax/json/nullable.json
+++ b/test/syntax/json/nullable.json
@@ -44,4 +44,4 @@
         "inheritance": null,
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/partial-interface.json b/test/syntax/json/partial-interface.json
index e95af2ba..8a3ce13b 100644
--- a/test/syntax/json/partial-interface.json
+++ b/test/syntax/json/partial-interface.json
@@ -48,4 +48,4 @@
         ],
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/primitives.json b/test/syntax/json/primitives.json
index 7568542f..9cfaabb2 100644
--- a/test/syntax/json/primitives.json
+++ b/test/syntax/json/primitives.json
@@ -280,4 +280,4 @@
         "inheritance": null,
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/putforwards.json b/test/syntax/json/putforwards.json
index 1b0a7b6b..d1692dfa 100644
--- a/test/syntax/json/putforwards.json
+++ b/test/syntax/json/putforwards.json
@@ -50,4 +50,4 @@
         "inheritance": null,
         "extAttrs": []
     }
-]
\ No newline at end of file
+]
diff --git a/test/syntax/json/sequence.json b/test/syntax/json/sequence.json
index 79821181..8cb98849 100644
--- a/test/syntax/json/sequence.json
+++ b/test/syntax/json/sequence.json
@@ -75,7 +75,6 @@
         "name": "Foo",
         "partial": false,
         "members": [
-
             {
                 "type": "operation",
                 "getter": false,
@@ -98,7 +97,6 @@
         "inheritance": null,
         "extAttrs": []
     },
-
     {
         "type": "interface",
         "name": "I",
diff --git a/test/syntax/json/setlike.json b/test/syntax/json/setlike.json
index cfaac319..d955dfd3 100644
--- a/test/syntax/json/setlike.json
+++ b/test/syntax/json/setlike.json
@@ -77,4 +77,3 @@
         "extAttrs": []
     }
 ]
-
diff --git a/test/syntax/json/typedef-union.json b/test/syntax/json/typedef-union.json
index 9c87672c..e812e1f0 100644
--- a/test/syntax/json/typedef-union.json
+++ b/test/syntax/json/typedef-union.json
@@ -1,49 +1,43 @@
 [
-   {
-      "type" : "typedef",
-      "idlType" : {
-         "nullable" : false,
-         "generic" : null,
-         "union" : true,
-         "idlType" : [
-            {
-               "union" : false,
-               "generic" : null,
-               "nullable" : false,
-               "array" : false,
-               "sequence" : false,
-               "idlType" : "ImageData"
-            },
-            {
-               "generic" : null,
-               "union" : false,
-               "nullable" : false,
-               "array" : false,
-               "idlType" : "HTMLImageElement",
-               "sequence" : false
-            },
-            {
-               "array" : false,
-               "sequence" : false,
-               "idlType" : "HTMLCanvasElement",
-               "generic" : null,
-               "union" : false,
-               "nullable" : false
-            },
-            {
-               "union" : false,
-               "generic" : null,
-               "nullable" : false,
-               "array" : false,
-               "sequence" : false,
-               "idlType" : "HTMLVideoElement"
-            }
-         ],
-         "sequence" : false,
-         "array" : false
-      },
-      "name" : "TexImageSource",
-      "extAttrs" : [],
-      "typeExtAttrs" : []
-   }
+    {
+        "type": "typedef",
+        "idlType": {
+            "sequence": false,
+            "generic": null,
+            "nullable": false,
+            "union": true,
+            "idlType": [
+                {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "ImageData"
+                },
+                {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "HTMLImageElement"
+                },
+                {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "HTMLCanvasElement"
+                },
+                {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": false,
+                    "idlType": "HTMLVideoElement"
+                }
+            ]
+        },
+        "name": "TexImageSource",
+        "extAttrs": []
+    }
 ]
diff --git a/test/syntax/json/uniontype.json b/test/syntax/json/uniontype.json
index c4725d41..4cd56d6c 100644
--- a/test/syntax/json/uniontype.json
+++ b/test/syntax/json/uniontype.json
@@ -1,118 +1,118 @@
 [
-   {
-      "partial": false,
-      "members": [
-         {
-            "idlType": {
-               "idlType": [
-                  {
-                     "union": false,
-                     "sequence": false,
-                     "generic": null,
-                     "idlType": "float",
-                     "nullable": false
-                  },
-                  {
-                     "idlType": [
+    {
+        "type": "interface",
+        "name": "Union",
+        "partial": false,
+        "members": [
+            {
+                "type": "attribute",
+                "static": false,
+                "stringifier": false,
+                "inherit": false,
+                "readonly": false,
+                "idlType": {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": true,
+                    "idlType": [
                         {
-                           "nullable": false,
-                           "idlType": "Date",
-                           "sequence": false,
-                           "generic": null,
-                           "union": false
+                            "sequence": false,
+                            "generic": null,
+                            "nullable": false,
+                            "union": false,
+                            "idlType": "float"
                         },
                         {
-                           "nullable": false,
-                           "idlType": "Event",
-                           "generic": null,
-                           "sequence": false,
-                           "union": false
-                        }
-                     ],
-                     "nullable": false,
-                     "sequence": false,
-                     "generic": null,
-                     "union": true
-                  },
-                  {
-                     "generic": null,
-                     "sequence": false,
-                     "idlType": [
-                        {
-                           "union": false,
-                           "sequence": false,
-                           "generic": null,
-                           "nullable": false,
-                           "idlType": "Node"
+                            "sequence": false,
+                            "generic": null,
+                            "nullable": false,
+                            "union": true,
+                            "idlType": [
+                                {
+                                    "sequence": false,
+                                    "generic": null,
+                                    "nullable": false,
+                                    "union": false,
+                                    "idlType": "Date"
+                                },
+                                {
+                                    "sequence": false,
+                                    "generic": null,
+                                    "nullable": false,
+                                    "union": false,
+                                    "idlType": "Event"
+                                }
+                            ]
                         },
                         {
-                           "nullable": false,
-                           "idlType": "DOMString",
-                           "sequence": false,
-                           "generic": null,
-                           "union": false
+                            "sequence": false,
+                            "generic": null,
+                            "nullable": true,
+                            "union": true,
+                            "idlType": [
+                                {
+                                    "sequence": false,
+                                    "generic": null,
+                                    "nullable": false,
+                                    "union": false,
+                                    "idlType": "Node"
+                                },
+                                {
+                                    "sequence": false,
+                                    "generic": null,
+                                    "nullable": false,
+                                    "union": false,
+                                    "idlType": "DOMString"
+                                }
+                            ]
                         }
-                     ],
-                     "nullable": true,
-                     "union": true
-                  }
-               ],
-               "nullable": false,
-               "generic": null,
-               "sequence": false,
-               "union": true
+                    ]
+                },
+                "name": "test",
+                "extAttrs": []
             },
-            "name": "test",
-            "inherit": false,
-            "type": "attribute",
-            "extAttrs": [],
-            "readonly": false,
-            "stringifier": false,
-            "static": false
-         },
-         {
-            "readonly": false,
-            "extAttrs": [],
-            "stringifier": false,
-            "static": false,
-            "name": "test2",
-            "idlType": {
-               "nullable": false,
-               "idlType": [
-                  {
-                     "extAttrs": [
+            {
+                "type": "attribute",
+                "static": false,
+                "stringifier": false,
+                "inherit": false,
+                "readonly": false,
+                "idlType": {
+                    "sequence": false,
+                    "generic": null,
+                    "nullable": false,
+                    "union": true,
+                    "idlType": [
                         {
-                           "name": "EnforceRange",
-                           "arguments": null,
-                           "type": "extended-attribute",
-                           "rhs": null
+                            "sequence": false,
+                            "generic": null,
+                            "nullable": false,
+                            "union": false,
+                            "idlType": "long",
+                            "extAttrs": [
+                                {
+                                    "name": "EnforceRange",
+                                    "arguments": null,
+                                    "type": "extended-attribute",
+                                    "rhs": null
+                                }
+                            ]
+                        },
+                        {
+                            "sequence": false,
+                            "generic": null,
+                            "nullable": false,
+                            "union": false,
+                            "idlType": "Date"
                         }
-                     ],
-                     "nullable": false,
-                     "idlType": "long",
-                     "generic": null,
-                     "sequence": false,
-                     "union": false
-                  },
-                  {
-                     "union": false,
-                     "sequence": false,
-                     "generic": null,
-                     "idlType": "Date",
-                     "nullable": false
-                  }
-               ],
-               "generic": null,
-               "sequence": false,
-               "union": true
-            },
-            "inherit": false,
-            "type": "attribute"
-         }
-      ],
-      "inheritance": null,
-      "name": "Union",
-      "extAttrs": [],
-      "type": "interface"
-   }
+                    ]
+                },
+                "name": "test2",
+                "extAttrs": []
+            }
+        ],
+        "inheritance": null,
+        "extAttrs": []
+    }
 ]
diff --git a/test/util/acquire.js b/test/util/acquire.js
new file mode 100644
index 00000000..6f37dd60
--- /dev/null
+++ b/test/util/acquire.js
@@ -0,0 +1,8 @@
+"use strict";
+
+const { collect } = require("./collect");
+const fs = require("fs");
+
+for (const test of collect("syntax")) {
+  fs.writeFileSync(test.jsonPath, `${JSON.stringify(test.ast, null, 4)}\n`)
+}
diff --git a/test/util/collect.js b/test/util/collect.js
new file mode 100644
index 00000000..83f288ac
--- /dev/null
+++ b/test/util/collect.js
@@ -0,0 +1,59 @@
+"use strict";
+
+const wp = require("../../lib/webidl2");
+const pth = require("path");
+const fs = require("fs");
+const jdp = require("jsondiffpatch");
+
+/**
+ * Collects test items from the specified directory
+ * @param {string} base
+ */
+function* collect(base, { expectError } = {}) {
+  base = pth.join(__dirname, "..", base);
+  const dir = pth.join(base, "idl");
+  const idls = fs.readdirSync(dir)
+    .filter(it => (/\.widl$/).test(it))
+    .map(it => pth.join(dir, it));
+
+  for (const path of idls) {
+    const optFile = pth.join(base, "opt", pth.basename(path)).replace(".widl", ".json");
+    let opt;
+    if (fs.existsSync(optFile))
+      opt = JSON.parse(fs.readFileSync(optFile, "utf8"));
+
+    try {
+      const ast = wp.parse(fs.readFileSync(path, "utf8").replace(/\r\n/g, "\n"), opt);
+      yield new TestItem({ ast, path, opt });
+    }
+    catch (error) {
+      if (expectError) {
+        yield new TestItem({ path, error });
+      }
+      else {
+        throw e;
+      }
+    }
+  }
+};
+
+
+class TestItem {
+  constructor({ ast, path, error, opt }) {
+    this.ast = ast;
+    this.path = path;
+    this.error = error;
+    this.opt = opt;
+    this.jsonPath = pth.join(pth.dirname(path), "../json", pth.basename(path).replace(".widl", ".json"));
+  }
+
+  readJSON() {
+    return JSON.parse(fs.readFileSync(this.jsonPath, "utf8"));
+  }
+
+  diff(target = this.readJSON()) {
+    return jdp.diff(target, this.ast);
+  }
+}
+
+module.exports.collect = collect;
diff --git a/test/writer.js b/test/writer.js
index f9ed6591..e84076b4 100644
--- a/test/writer.js
+++ b/test/writer.js
@@ -1,32 +1,16 @@
 "use strict";
 
+const { collect } = require("./util/collect");
 const wp = require("../lib/webidl2");
 const writer = require("../lib/writer");
 const expect = require("expect");
-const pth = require("path");
-const fs = require("fs");
-const jdp = require("jsondiffpatch");
 const debug = true;
 
 describe("Rewrite and parses all of the IDLs to produce the same ASTs", () => {
-  const dir = pth.join(__dirname, "syntax/idl");
-  const skip = {}; // use if we have a broken test
-  const idls = fs.readdirSync(dir)
-    .filter(it => (/\.widl$/).test(it) && !skip[it])
-    .map(it => pth.join(dir, it));
-
-  for (const idl of idls) {
-    const json = pth.join(__dirname, "syntax/json", pth.basename(idl).replace(".widl", ".json"));
-
-    it(`should produce the same AST for ${idl}`, () => {
+  for (const test of collect("syntax")) {
+    it(`should produce the same AST for ${test.path}`, () => {
       try {
-        const ast = JSON.parse(fs.readFileSync(json, "utf8"));
-        const optFile = pth.join(__dirname, "syntax/opt", pth.basename(json));
-        let opt = undefined;
-        if (fs.existsSync(optFile))
-          opt = JSON.parse(fs.readFileSync(optFile, "utf8"));
-        const diff = jdp.diff(ast,
-          wp.parse(writer.write(ast), opt));
+        const diff = test.diff(wp.parse(writer.write(test.ast), test.opt));
         if (diff && debug) console.log(JSON.stringify(diff, null, 4));
         expect(diff).toBe(undefined);
       }