syntax_data: {"ast_node_type":"other","tokens":[{"end":66,"kind":"keyword","start":0,"text":"assert_eq!(srcfbp1.sf.name,"}]}
source_snippet:     assert_eq!(srcfbp1.sf.name, PathBuf::from("blork.rs").into());
context_before:     let srcfbp1 = sm.lookup_byte_offset(BytePos(23));
context_after:     assert_eq!(srcfbp1.pos, BytePos(23));