---
source: crates/biome_js_analyze/tests/spec_tests.rs
expression: filename.test.invalid-extension.ts
---
# Input
```ts

```

# Diagnostics
```
filename.test.invalid-extension.ts lint/style/useFilenamingConvention ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The file extension should be in lowercase without any special characters.
  

```