sinelaw/fresh · error · io::Error (Unsupported)

Filesystem not available

Error message

Filesystem not available

What it means

NoopFileSystem is a stub implementation of the filesystem trait used in tests/headless contexts. Every filesystem operation on it funnels through the private unsupported() helper, which returns io::ErrorKind::Unsupported with the message 'Filesystem not available'. It signals that no real filesystem is backed by this model instance.

Solutions

1. Construct the model/session with a real filesystem implementation instead of NoopFileSystem
2. If this is a test, either assert on the Unsupported error or switch to a tempdir-backed filesystem
3. Guard filesystem-touching code paths so they are skipped when the backend is NoopFileSystem

Example fix

// before
let model = Model::new(NoopFileSystem::default());
model.read_file("/tmp/x.txt")?; // Unsupported: Filesystem not available
// after
let model = Model::new(RealFileSystem::new());
model.read_file("/tmp/x.txt")?;

fn has_real_fs(model: &Model) -> bool { !std::ptr::eq(model.fs_type_id(), &std::any::TypeId::of::<NoopFileSystem>()) } // or track a bool at construction

fn is_noop_fs(fs: &dyn FileSystem) -> bool { fs.as_any().is::<NoopFileSystem>() }

match model.write_file(path, data) { Err(e) if e.kind() == io::ErrorKind::Unsupported => eprintln!("no filesystem backend"), other => other?, }

When it happens

Trigger: Any filesystem operation (read, write, metadata, listing) invoked on a model/session constructed with NoopFileSystem — typically headless tests, scripting sessions, or runs where the model was explicitly created without a real filesystem backend.

Common situations: Running editor logic in tests or CI with NoopFileSystem::default() as the backend; forgetting to swap in a real filesystem implementation before exercising file operations; using a script or harness that hardcodes the noop backend.

Understand the failure class

Background: "unsupported platform" / "not supported on this platform" errors: what they mean and how to fix them — this error's family across 47 libraries.

Related errors

• Failed to read
• Failed to read plugin
• home directory not found
• read_range: expected
• NotFound

AI-assisted analysis of sinelaw/fresh@67894ca546 (2026-09-13). Data as JSON: /api/errors/af4f12d1c6495907. Report an issue: GitHub.

Appendix: source

Thrown at crates/fresh-editor-core/src/model/filesystem.rs:1641

        }
        Ok(())
    }
}

// ============================================================================
// NoopFileSystem Implementation
// ============================================================================

/// No-op filesystem that returns errors for all operations
///
/// Used as a placeholder or in WASM builds where a VirtualFileSystem
/// should be used instead.
#[derive(Debug, Clone, Copy, Default)]
pub struct NoopFileSystem;

impl NoopFileSystem {
    fn unsupported<T>() -> io::Result<T> {
        Err(io::Error::new(
            io::ErrorKind::Unsupported,
            "Filesystem not available",
        ))
    }
}

impl FileSystem for NoopFileSystem {
    fn read_file(&self, _path: &Path) -> io::Result<Vec<u8>> {
        Self::unsupported()
    }

    fn read_range(&self, _path: &Path, _offset: u64, _len: usize) -> io::Result<Vec<u8>> {
        Self::unsupported()
    }

    fn write_file(&self, _path: &Path, _data: &[u8]) -> io::Result<()> {
        Self::unsupported()
    }

View on GitHub (pinned to 67894ca546)