fix: prevent cli tool from choking because of $schema property in rc …

…json file (#1297)

src/lib/getNcuRc.ts

@@ -1,5 +1,6 @@
 import flatten from 'lodash/flatten'
 import map from 'lodash/map'
+import omit from 'lodash/omit'
 import path from 'path'
 import { rcFile } from 'rc-config-loader'
 import { cliOptionsMap } from '../cli-options'
@@ -24,12 +25,18 @@ async function getNcuRc({ color, configFileName, configFilePath, packageFile }:
   const { default: chalkDefault, Chalk } = await import('chalk')
   const chalk = color ? new Chalk({ level: 1 }) : chalkDefault
 
-  const result = rcFile('ncurc', {
+  const rawResult = rcFile('ncurc', {
     configFileName: configFileName || '.ncurc',
     defaultExtension: ['.json', '.yml', '.js'],
     cwd: configFilePath || (packageFile ? path.dirname(packageFile) : undefined),
   })
 
+  const result = {
+    filePath: rawResult?.filePath,
+    // Prevent the cli tool from choking because of an unknown option "$schema"
+    config: omit(rawResult?.config, '$schema'),
+  }
+
   // validate arguments here to provide a better error message
   const unknownOptions = Object.keys(result?.config || {}).filter(arg => !cliOptionsMap[arg])
   if (unknownOptions.length > 0) {

test/rc-config.test.ts

@@ -203,4 +203,19 @@ describe('rc-config', () => {
       await fs.rm(tempDir, { recursive: true, force: true })
     }
   })
+
+  it('should not crash if because of $schema property', async () => {
+    const tempDir = await fs.mkdtemp(path.join(os.tmpdir(), 'npm-check-updates-'))
+    const configFile = path.join(tempDir, '.ncurc.json')
+    const pkgFile = path.join(tempDir, 'package.json')
+    await fs.writeFile(configFile, JSON.stringify({ $schema: 'schema url' }), 'utf-8')
+    await fs.writeFile(pkgFile, JSON.stringify({ dependencies: { axios: '1.0.0' } }), 'utf-8')
+
+    try {
+      // awkwardly, we have to set mergeConfig to enable autodetecting the rcconfig because otherwise it is explicitly disabled for tests
+      await spawn('node', [bin, '--mergeConfig'], { cwd: tempDir })
+    } finally {
+      await fs.rm(tempDir, { recursive: true, force: true })
+    }
+  })
 })