Run inputs through sb3fix if validate() fails

Closes TurboWarp/scratch-vm#200
Some of the above tests that check for validate() rejecting invalid inputs would
ideally fail now, but sb3fix is still an experiment. We haven't seen projects that
are invalid in these ways in the wild so not a priority.

lib/validate.js

@@ -7,7 +7,7 @@ var sprite2Schema = require('./sprite2_schema.json');
 var sprite3Schema = require('./sprite3_schema.json');
 ajv.addSchema(sb2Defs).addSchema(sb3Defs);
 
-module.exports = function (isSprite, input, callback) {
+var validate = function (isSprite, input, callback) {
     var validateSb3 = ajv.compile(isSprite ? sprite3Schema : sb3Schema);
     var isValidSb3 = validateSb3(input);
     if (isValidSb3) {
@@ -30,3 +30,32 @@ module.exports = function (isSprite, input, callback) {
 
     callback(validationErrors);
 };
+
+module.exports = function (isSprite, input, callback) {
+    // If validate fails, try using sb3fix to salvage the input
+    validate(isSprite, input, function (err, result) {
+        if (!err) {
+            callback(null, result);
+            return;
+        }
+
+        try {
+            // Load slightly lazily as this is an edge case
+            // eslint-disable-next-line global-require
+            var sb3fix = require('@turbowarp/sb3fix');
+
+            var fixed = sb3fix.fixJSON(input);
+            validate(isSprite, fixed, function (err2, result2) {
+                if (err2) {
+                    // Original validation error will be most useful
+                    callback(err);
+                } else {
+                    callback(null, result2);
+                }
+            });
+        } catch (sb3fixError) {
+            // The original validation error will be most useful
+            callback(err);
+        }
+    });
+};

package.json

@@ -21,6 +21,7 @@
   },
   "dependencies": {
     "@turbowarp/json": "^0.1.1",
+    "@turbowarp/sb3fix": "^0.2.0",
     "ajv": "6.3.0",
     "jszip": "^3.10.1",
     "pify": "4.0.1"

test/unit/validate.js

@@ -118,3 +118,31 @@ test('sb3 errors listed before sb2 errors', function (t) {
         t.end();
     });
 });
+
+test('Uses sb3fix if validation fails', function (t) {
+    var invalidSprite = {
+        isStage: false,
+        name: 'Sprite1',
+        variables: {},
+        lists: {},
+        broadcasts: {},
+        blocks: {},
+        comments: {},
+        currentCostume: 0,
+        costumes: [], // should not be empty!
+        sounds: [],
+        volume: 100,
+        visible: true,
+        x: 0,
+        y: 0,
+        size: 100,
+        direction: 90,
+        draggable: false,
+        rotationStyle: 'all around'
+    };
+    validate(true, invalidSprite, function (err, res) {
+        t.equal(err, null);
+        t.equal(res.costumes.length, 1); // sb3fix will add a costume
+        t.end();
+    });
+});