message: Fix flaky unit tests due to non-existent cache
diff: @@ -322,7 +322,9 @@ impl Fixture {
  }
  pub fn cache(&self) -> Cache {
  - Cache::at(&self.cache_dir())
  + let cache_dir = self.cache_dir();
  + fs::create_dir_all(&cache_dir).unwrap();
  + Cache::at(&cache_dir)
  }
  /// The `step_install_wasm_bindgen` and `step_run_wasm_bindgen` steps only
  