Add minimal failing test

src/lang/wasm.test.ts

@@ -0,0 +1,13 @@
+import { err } from 'lib/trap'
+import { parse } from './wasm'
+import { enginelessExecutor } from 'lib/testHelpers'
+
+it('can execute parsed AST', async () => {
+  const code = `x = 1
+// A comment.`
+  const ast = parse(code)
+  expect(err(ast)).toEqual(false)
+  const execState = await enginelessExecutor(ast)
+  expect(err(ast)).toEqual(false)
+  expect(execState.memory.get('x')).toEqual(1)
+})