Merge pull request #1524 from kchadha/only-undefined-in-c-block-fix

Resolve project load error with undefined opcodes inside c/e blocks.

src/serialization/sb2.js

@@ -833,6 +833,10 @@ const parseBlock = function (sb2block, addBroadcastMsg, getVariableId, extension
                     // Update commentIndex
                     commentIndex = parsedBlockDesc[1];
                 }
+                // Check if innerBlocks is an empty list.
+                // This indicates that all the inner blocks from the sb2 have
+                // unknown opcodes and have been skipped.
+                if (innerBlocks.length === 0) continue;
                 let previousBlock = null;
                 for (let j = 0; j < innerBlocks.length; j++) {
                     if (j === 0) {

test/integration/unknown-opcode-in-c-block.js

@@ -0,0 +1,39 @@
+const path = require('path');
+const test = require('tap').test;
+const makeTestStorage = require('../fixtures/make-test-storage');
+const readFileToBuffer = require('../fixtures/readProjectFile').readFileToBuffer;
+const VirtualMachine = require('../../src/index');
+
+const uri = path.resolve(__dirname, '../fixtures/unknown-opcode-in-c-block.sb2');
+const project = readFileToBuffer(uri);
+
+test('unknown opcode', t => {
+    const vm = new VirtualMachine();
+    vm.attachStorage(makeTestStorage());
+
+    vm.start();
+    vm.clear();
+    vm.setCompatibilityMode(false);
+    vm.setTurboMode(false);
+    vm.loadProject(project).then(() => {
+        vm.greenFlag();
+
+        // The project has 3 blocks in a single stack:
+        //      when green flag => forever [ => "undefined"]
+        // the "undefined" block has opcode "foo" and was created by dragging
+        // a custom procedure caller named foo from the backpack into a project.
+        // It should be parsed in without error and it should
+        // leave the forever block empty.
+        const blocks = vm.runtime.targets[1].blocks;
+        const topBlockId = blocks.getScripts()[0];
+        const secondBlockId = blocks.getNextBlock(topBlockId);
+        const innerBlockId = blocks.getBranch(secondBlockId, 0);
+
+        t.equal(blocks.getBlock(topBlockId).opcode, 'event_whenflagclicked');
+        t.equal(blocks.getBlock(secondBlockId).opcode, 'control_forever');
+        t.equal(innerBlockId, null);
+
+        t.end();
+        process.nextTick(process.exit);
+    });
+});