Struct MemFs 

pub struct MemFs { /* private fields */ }

In-memory filesystem for tests.

Backed by a BTreeMap (files) and BTreeSet (directories) for deterministic, sorted output. Interior mutability via RefCell lets callers hold &MemFs (shared reference) while still mutating state.

Fidelity contract: write returns an error when the parent directory has not been registered via create_dir_all, faithfully modelling real OS behaviour so tests cannot accidentally skip the parent-creation step.

This type is available in non-test builds so integration tests in later units can import it without feature flags.

Implementations

impl MemFs

pub fn new() -> Self

Trait Implementations

impl Default for MemFs

fn default() -> Self

Returns the “default value” for a type.

impl Fs for MemFs

fn create_dir_all(&self, path: &Path) -> Result<(), SessionError>

Create path and all missing ancestors, like mkdir -p.

fn exists(&self, path: &Path) -> bool

Return true if path exists (file or directory).

fn read(&self, path: &Path) -> Result<Vec<u8>, SessionError>

Read the entire contents of the file at path.

fn write(&self, path: &Path, data: &[u8]) -> Result<(), SessionError>

Write data to path, replacing any existing content.

fn append(&self, path: &Path, data: &[u8]) -> Result<(), SessionError>

Append data to the file at path, creating it if absent. Like write, it errors if the parent directory does not exist.

fn read_dir(&self, path: &Path) -> Result<Vec<PathBuf>, SessionError>

List immediate children (files and directories) of path, sorted for deterministic iteration.

fn rename(&self, from: &Path, to: &Path) -> Result<(), SessionError>

Rename / move from to to.

fn remove(&self, path: &Path) -> Result<(), SessionError>

Remove a file or directory tree at path.