fix(test): output a .js bundle, not .ts

- woooops... was wondering why it was `.ts`; turns out because I wrote the `output.file` setting that way 😅 😅 😅

- also add a missing comment in errors for consistency
- and put code checks _after_ file structure checks, since that's a deeper check

Author: agilgur5

__tests__/integration/errors.spec.ts

@@ -40,10 +40,10 @@ test("integration - errors - abortOnError: false / check: false", async () => {
   const { output: output2 } = await genBundle({ check: false });
   expect(output).toEqual(output2);
 
-  expect(output[0].fileName).toEqual("index.ts");
+  expect(output[0].fileName).toEqual("index.js");
   expect(output[1].fileName).toEqual("index.d.ts");
   expect(output[2].fileName).toEqual("index.d.ts.map");
-  expect(output.length).toEqual(3);
+  expect(output.length).toEqual(3); // no other files
   expect(onwarn).toBeCalledTimes(1);
 });
 

__tests__/integration/helpers.ts

@@ -22,7 +22,7 @@ export async function genBundle ({ input, tsconfig, cacheRoot, extraOpts, onwarn
   });
 
   const esm = await bundle.generate({
-    file: "./dist/index.ts",
+    file: "./dist/index.js",
     format: "esm",
     exports: "named",
   });

__tests__/integration/no-errors.spec.ts

@@ -30,17 +30,17 @@ test("integration - no errors", async () => {
   const { output: outputWithCache } = await genBundle();
   expect(output).toEqual(outputWithCache);
 
-  // JS file should be bundled by Rollup, even though rpt2 does not resolve it (as Rollup natively understands ESM)
-  expect(output[0].code).toEqual(expect.stringContaining("identity"));
-
-  expect(output[0].fileName).toEqual("index.ts");
+  expect(output[0].fileName).toEqual("index.js");
   expect(output[1].fileName).toEqual("index.d.ts");
   expect(output[2].fileName).toEqual("index.d.ts.map");
   expect(output[3].fileName).toEqual("some-import.d.ts");
   expect(output[4].fileName).toEqual("some-import.d.ts.map");
   expect(output[5].fileName).toEqual("type-only-import.d.ts");
   expect(output[6].fileName).toEqual("type-only-import.d.ts.map");
   expect(output.length).toEqual(7); // no other files
+
+  // JS file should be bundled by Rollup, even though rpt2 does not resolve it (as Rollup natively understands ESM)
+  expect(output[0].code).toEqual(expect.stringContaining("identity"));
 });
 
 test("integration - no errors - no declaration maps", async () => {
@@ -50,7 +50,7 @@ test("integration - no errors - no declaration maps", async () => {
     clean: true,
   });
 
-  expect(output[0].fileName).toEqual("index.ts");
+  expect(output[0].fileName).toEqual("index.js");
   expect(output[1].fileName).toEqual("index.d.ts");
   expect(output[2].fileName).toEqual("some-import.d.ts");
   expect(output[3].fileName).toEqual("type-only-import.d.ts");
@@ -65,6 +65,6 @@ test("integration - no errors - no declarations", async () => {
     clean: true,
   });
 
-  expect(output[0].fileName).toEqual("index.ts");
+  expect(output[0].fileName).toEqual("index.js");
   expect(output.length).toEqual(1); // no other files
 });