feat: discard npmrc if containing variables

.npmrc files will fail during lock file generation if they contain unexpanded variables, so it’s better to discard them instead.

lib/manager/npm/extract/index.js

@@ -58,7 +58,15 @@ async function extractDependencies(content, packageFile, config) {
     npmrc = await platform.getFile(
       upath.join(path.dirname(packageFile), '.npmrc')
     );
-    if (!npmrc) {
+    if (npmrc) {
+      if (
+        npmrc.includes('=${') &&
+        !(config.global && config.global.exposeEnv)
+      ) {
+        logger.info('Discarding .npmrc file with variables');
+        npmrc = undefined;
+      }
+    } else {
       npmrc = undefined;
     }
   }

test/manager/npm/extract/index.spec.js

@@ -75,6 +75,21 @@ describe('manager/npm/extract', () => {
       );
       expect(res).toMatchSnapshot();
     });
+    it('finds and discards .npmrc', async () => {
+      platform.getFile = jest.fn(fileName => {
+        if (fileName === '.npmrc') {
+          // eslint-disable-next-line
+          return '//registry.npmjs.org/:_authToken=${NPM_AUTH_TOKEN}\n';
+        }
+        return null;
+      });
+      const res = await npmExtract.extractDependencies(
+        input01Content,
+        'package.json',
+        { global: {} }
+      );
+      expect(res.npmrc).toBeUndefined();
+    });
     it('finds lerna', async () => {
       platform.getFile = jest.fn(fileName => {
         if (fileName === 'lerna.json') {