Function assert_buffer_snapshot 

pub fn assert_buffer_snapshot(
    name: &str,
    buf: &Buffer,
    base_dir: &str,
    mode: MatchMode,
)

Assert that a buffer’s text representation matches a stored snapshot.

Arguments

• name – Snapshot identifier (used as the .snap filename).
• buf – The buffer to compare.
• base_dir – Root directory for snapshot storage (use env!("CARGO_MANIFEST_DIR")).
• mode – How to compare the text (exact, trim trailing, or fuzzy).

Panics

• If the snapshot file does not exist and BLESS=1 is not set.
• If the buffer output does not match the stored snapshot.

Updating Snapshots

Set BLESS=1 to write the current buffer output as the new snapshot:

BLESS=1 cargo test