Report syntax errors prior to running wizer so that we can get custom error reporting

Author: Jake Champion

integration-tests/cli/invalid.test.js

@@ -9,8 +9,15 @@ test('should return non-zero exit code on syntax errors', async function (t) {
     t.teardown(async function () {
         await cleanup();
     });
-    await writeFile('./bin/index.js', '@')
-    const { code } = await execute('node', cli);
-    
+    await writeFile('./bin/index.js', '\n\n\n"hello";@')
+    const { code, stdout, stderr } = await execute('node', cli);
+    t.alike(stdout, []);
+    t.alike(stderr, [
+        '{{base}}/bin/index.js:4',
+        '"hello";@',
+        '^',
+        'SyntaxError: Invalid or unexpected token'
+    ]);
+
     t.is(code, 1);
 });

src/compileApplicationToWasm.js

@@ -5,6 +5,7 @@ import { isFile } from "./isFile.js";
 import { isFileOrDoesNotExist } from "./isFileOrDoesNotExist.js";
 import wizer from "@jakechampion/wizer";
 import { precompile } from "./precompile.js";
+import { containsSyntaxErrors } from "./containsSyntaxErrors.js";
 
 export async function compileApplicationToWasm(input, output, wasmEngine) {
   try {
@@ -31,7 +32,7 @@ export async function compileApplicationToWasm(input, output, wasmEngine) {
     );
     process.exit(1);
   }
-  // TODO: Enhancement - Check that input is valid JavaScript syntax before Wizening
+
   try {
     if (!(await isFile(wasmEngine))) {
       console.error(
@@ -72,6 +73,10 @@ export async function compileApplicationToWasm(input, output, wasmEngine) {
     process.exit(1);
   }
 
+  if (containsSyntaxErrors(input)) {
+    process.exit(1);
+  }
+
   let application = precompile(inputContents);
 
   try {

src/containsSyntaxErrors.js

@@ -0,0 +1,23 @@
+import { spawnSync } from "node:child_process";
+
+// TODO: We should check that the syntax used is supported by our version of SpiderMonkey
+export function containsSyntaxErrors(input) {
+    let nodeProcess = spawnSync(
+        process.execPath,
+        [
+            "--check",
+            input,
+        ],
+        {
+            stdio: [null, null, null],
+            shell: true,
+            encoding: "utf-8",
+        }
+    );
+    if (nodeProcess.status === 0) {
+        return false;
+    } else {
+        console.error(nodeProcess.stderr.split('\nSyntaxError: Invalid or unexpected token\n')[0] + '\nSyntaxError: Invalid or unexpected token\n')
+        return true;
+    }
+}