diff --git a/lib/generator.test.js b/lib/generator.test.js
index 5624626..a55a671 100644
--- a/lib/generator.test.js
+++ b/lib/generator.test.js
@@ -280,7 +280,7 @@ test("ignore multiple files of certain extension", async() => {
 })
 
 test("content of explicitly added files from common folder is correct", async() => {
-  expect.assertions(3)
+  expect.assertions(9)
 
   const s = generator("template", "app", {
     variables: {
@@ -305,4 +305,11 @@ test("content of explicitly added files from common folder is correct", async()
   expect(fs.readFileSync("app/scripts/three.js", {
     encoding: "utf8",
   })).toBe("console.log(\"this is three.js\")")
+
+  expect(fs.existsSync("app/scripts/one.ts")).toBe(false)
+  expect(fs.existsSync("app/scripts/two.ts")).toBe(false)
+  expect(fs.existsSync("app/scripts/three.ts")).toBe(false)
+  expect(fs.existsSync("app/scripts/one.mjs")).toBe(false)
+  expect(fs.existsSync("app/scripts/two.mjs")).toBe(false)
+  expect(fs.existsSync("app/scripts/three.mjs")).toBe(false)
 })
\ No newline at end of file