bring back support for Node <= 12.22.0

mochajs · May 22, 2021 · ed1f4a0 · ed1f4a0
1 parent 7680f12
commit ed1f4a0
Showing 1 changed file with 42 additions and 16 deletions.
diff --git a/lib/esm-utils.js b/lib/esm-utils.js
@@ -30,23 +30,32 @@ const formattedImport = async file => {
   return import(file);
 };
 
-exports.requireOrImport = async file => {
-  if (path.extname(file) === '.mjs') {
-    return formattedImport(file);
-  }
-  try {
-    return dealWithExports(await formattedImport(file));
-  } catch (err) {
-    if (
-      err.code === 'ERR_MODULE_NOT_FOUND' ||
-      err.code === 'ERR_UNKNOWN_FILE_EXTENSION'
-    ) {
-      return require(file);
-    } else {
-      throw err;
+const hasStableEsmImplementation = (() => {
+  const [major, minor] = process.version.split('.');
+  // ESM is stable from v12.22.0 onward
+  // https://nodejs.org/api/esm.html#esm_modules_ecmascript_modules
+  return parseInt(major.slice(1), 10) > 12 || parseInt(minor, 10) >= 22;
+})();
+
+exports.requireOrImport = hasStableEsmImplementation
+  ? async file => {
+      if (path.extname(file) === '.mjs') {
+        return formattedImport(file);
+      }
+      try {
+        return dealWithExports(await formattedImport(file));
+      } catch (err) {
+        if (
+          err.code === 'ERR_MODULE_NOT_FOUND' ||
+          err.code === 'ERR_UNKNOWN_FILE_EXTENSION'
+        ) {
+          return require(file);
+        } else {
+          throw err;
+        }
+      }
     }
-  }
-};
+  : implemenetationOfRequireOrImportForUnstableEsm;
 
 function dealWithExports(module) {
   if (module.default) {
@@ -63,3 +72,20 @@ exports.loadFilesAsync = async (files, preLoadFunc, postLoadFunc) => {
     postLoadFunc(file, result);
   }
 };
+
+async function implemenetationOfRequireOrImportForUnstableEsm(file) {
+  if (path.extname(file) === '.mjs') {
+    return formattedImport(file);
+  }
+  // This is currently the only known way of figuring out whether a file is CJS or ESM in
+  // Node.js that doesn't necessitate calling `import` first.
+  try {
+    return require(file);
+  } catch (err) {
+    if (err.code === 'ERR_REQUIRE_ESM') {
+      return formattedImport(file);
+    } else {
+      throw err;
+    }
+  }
+}