chore: add more meaningful error message for incorrect config names

Author: haoqunjiang

src/index.ts

@@ -70,6 +70,25 @@ export default function createConfig({
     })
   }
 
+  // More meaningful error message for the user, in case they didn't know the correct config name.
+  for (const name of configNamesToExtend) {
+    if (!tseslint.configs[name]) {
+      const nameInCamelCase = name.replace(/-([a-z])/g, (_, letter) =>
+        letter.toUpperCase(),
+      )
+
+      // @ts-expect-error
+      if (tseslint.configs[nameInCamelCase]) {
+        throw new Error(
+          `The config name "${name}" is not supported in "extends". ` +
+            `Please use "${nameInCamelCase}" instead.`,
+        )
+      }
+
+      throw new Error(`Unknown config name in "extends": ${name}.`)
+    }
+  }
+
   const mayHaveJsxInSfc = supportedScriptLangs.jsx || supportedScriptLangs.tsx
   const needsTypeAwareLinting = configNamesToExtend.some(
     name =>

test/index.spec.ts

@@ -191,3 +191,14 @@ test('#87: should not error if the project root has an older version of espree i
   const { stdout } = await runLintAgainst('with-older-espree', FROM_FIXTURES)
   expect(stdout).toMatch(WHITESPACE_ONLY)
 })
+
+test('should guide user to use camelCase names in "extends"', async () => {
+  const eslintConfigPath = path.join(__dirname, '../examples/type-checked/eslint.config.js')
+  const { modify, restore } = setupFileMutations(eslintConfigPath)
+  modify((oldContents) => oldContents.replace('recommendedTypeChecked', 'recommended-type-checked'))
+  const { failed, stderr } = await runLintAgainst('type-checked')
+  restore()
+
+  expect(failed).toBe(true)
+  expect(stderr).contain('Please use "recommendedTypeChecked"')
+})