fix: Ensure revert() does revert correctly

Fixes #90 Restores compatibility with esm library
danez · Jan 24, 2022 · 4e1b015 · 4e1b015
1 parent 7083385
commit 4e1b015
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/src/index.js b/src/index.js
@@ -140,7 +140,11 @@ export function addHook(hook, opts = {}) {
       // if the current loader for the extension is our loader then unregister it and set the oldLoader again
       // if not we can not do anything as we cannot remove a loader from within the loader-chain
       if (Module._extensions[ext] === loaders[ext]) {
-        Module._extensions[ext] = oldLoaders[ext];
+        if (!oldLoaders[ext]) {
+          delete Module._extensions[ext];
+        } else {
+          Module._extensions[ext] = oldLoaders[ext];
+        }
       }
     });
   };

diff --git a/test/basics.js b/test/basics.js
@@ -100,6 +100,7 @@ test('reverts to previous loader', (t) => {
 });
 
 test('reverts to nothing if no previous loader', (t) => {
+  const oldKeys = Object.keys(require.extensions);
   t.is(require.extensions['.foo2js'], undefined);
   const revert = t.context.addHook((code) => code.replace('@@a', '<a>'), {
     exts: ['.foo2js'],
@@ -110,4 +111,5 @@ test('reverts to nothing if no previous loader', (t) => {
   revert();
 
   t.is(require.extensions['.foo2js'], undefined);
+  t.deepEqual(Object.keys(require.extensions), oldKeys);
 });