feat(config-validator): read filenames from CLI arguments

docs/usage/getting-started/installing-onboarding.md

@@ -135,6 +135,14 @@ If you want to make config edits directly, follow these steps:
 1. Validate your config by running `renovate-config-validator`
 1. If the improved config passes the validation, merge the branch into your mainline branch
 
+The validator program checks files based on multiple inputs:
+
+- Filenames as CLI arguments
+- `RENOVATE_CONFIG_FILE` environment variable
+- All [default locations](../configuration-options.md) if the files exist
+
+At the moment, all locations are validated without any precedence or deduplication.
+
 You can configure a [pre-commit](https://pre-commit.com) hook to validate your configuration automatically.
 Please check out the [`renovatebot/pre-commit-hooks` repository](https://github.com/renovatebot/pre-commit-hooks) for more information.
 

lib/config-validator.ts

@@ -50,6 +50,26 @@ type PackageJson = {
 };
 
 (async () => {
+  for (const file of process.argv.slice(2)) {
+    try {
+      if (!(await pathExists(file))) {
+        returnVal = 1;
+        logger.error(`${file} does not exist`);
+        break;
+      }
+      const parsedContent = await getParsedContent(file);
+      try {
+        logger.info(`Validating ${file}`);
+        await validate(file, parsedContent);
+      } catch (err) {
+        logger.warn({ err }, `${file} is not valid Renovate config`);
+        returnVal = 1;
+      }
+    } catch (err) {
+      logger.warn({ err }, `${file} could not be parsed`);
+      returnVal = 1;
+    }
+  }
   for (const file of configFileNames.filter(
     (name) => name !== 'package.json'
   )) {