freeze defaultLoaders so it cannot be mutated causing unexpected results

cosmiconfig · Oct 22, 2019 · 7a0f0e6 · 7a0f0e6
1 parent 26b65bb
commit 7a0f0e6
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Showing 2 changed files with 11 additions and 3 deletions.
diff --git a/src/index.ts b/src/index.ts
@@ -79,13 +79,14 @@ function cosmiconfigSync(moduleName: string, options: OptionsSync = {}) {
   } as const;
 }
 
-const defaultLoaders = {
+// do not allow mutation of default loaders. Make sure it is set inside options
+const defaultLoaders = Object.freeze({
   '.js': loaders.loadJs,
   '.json': loaders.loadJson,
   '.yaml': loaders.loadYaml,
   '.yml': loaders.loadYaml,
   noExt: loaders.loadYaml,
-} as const;
+} as const);
 
 function normalizeOptions(
   moduleName: string,

diff --git a/test/index.test.ts b/test/index.test.ts
@@ -3,6 +3,7 @@ import { TempDir } from './util';
 import {
   cosmiconfig as cosmiconfigModule,
   cosmiconfigSync as cosmiconfigSyncModule,
+  defaultLoaders,
   LoaderSync,
 } from '../src';
 
@@ -195,7 +196,7 @@ describe('cosmiconfig', () => {
 
     const expectedError =
       'loader for extension ".things" is not a function (type provided: "number"), so searchPlaces item ".foorc.things" is invalid';
-    test('async', async () => {
+    test('async', () => {
       expect(() =>
         // @ts-ignore
         cosmiconfig('foo', explorerOptions),
@@ -209,4 +210,10 @@ describe('cosmiconfig', () => {
       ).toThrow(expectedError);
     });
   });
+
+  describe('cannot mutate default loaders', () => {
+    const expectedError = "Cannot delete property '.js' of #<Object>";
+    // @ts-ignore
+    expect(() => delete defaultLoaders['.js']).toThrow(expectedError);
+  });
 });