Validate moshcode run options

bin/moshcode.mjs

@@ -107,6 +107,14 @@ async function main() {
         catch (e) { console.error(String(e.message || e)); process.exit(1); }
       }
       else if (a === "--dry-run") dryRun = true;
+      else if (a.startsWith("-")) {
+        console.error(`moshcode run: unknown option ${a}`);
+        process.exit(1);
+      }
+      else if (file) {
+        console.error(`moshcode run: expected one script file, got ${JSON.stringify(file)} and ${JSON.stringify(a)}`);
+        process.exit(1);
+      }
       else file = a;
     }
     const src = file ? readScript(file) : (fs.existsSync(EXAMPLE) ? fs.readFileSync(EXAMPLE, "utf8") : DEFAULT_SCRIPT);

test/run-options.test.mjs

@@ -0,0 +1,35 @@
+import assert from "node:assert/strict";
+import { mkdtempSync, writeFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { spawnSync } from "node:child_process";
+import test from "node:test";
+
+const BIN = fileURLToPath(new URL("../bin/moshcode.mjs", import.meta.url));
+
+function run(args) {
+  return spawnSync(process.execPath, [BIN, "run", ...args], {
+    encoding: "utf8",
+  });
+}
+
+test("run rejects unknown options before treating them as files", () => {
+  const result = run(["--dryrun"]);
+
+  assert.equal(result.status, 1);
+  assert.match(result.stderr, /moshcode run: unknown option --dryrun/);
+});
+
+test("run rejects multiple script files", () => {
+  const dir = mkdtempSync(join(tmpdir(), "moshcode-run-"));
+  const first = join(dir, "first.mosh");
+  const second = join(dir, "second.mosh");
+  writeFileSync(first, 'say("one");\n');
+  writeFileSync(second, 'say("two");\n');
+
+  const result = run([first, second, "--dry-run"]);
+
+  assert.equal(result.status, 1);
+  assert.match(result.stderr, /moshcode run: expected one script file/);
+});