Add test for sb3 creation being deterministic over time

test/integration/tw_deterministic_sb3.js

@@ -0,0 +1,14 @@
+const {test} = require('tap');
+const VM = require('../../src/virtual-machine');
+
+test('saveProjectSb3 is deterministic over time', t => {
+    const vm = new VM();
+    Promise.all([
+        vm.saveProjectSb3('nodebuffer'),
+        // Zip modification time is only accurate to the second
+        new Promise(resolve => setTimeout(resolve, 1000)).then(() => vm.saveProjectSb3('nodebuffer'))
+    ]).then(([a, b]) => {
+        t.same(a, b);
+        t.end();
+    });
+});