pub fn as_path(&self) -> &Path {
        match self {
            Self::CargoManifestDescription(path) => path.as_path(),
            Self::CommonMarkFile(path) => path.as_path(),
            Self::RustDocTest(path, _) => path.as_path(),
            Self::RustSourceFile(path) => path.as_path(),
            Self::TestEntityCommonMark => {
                lazy_static::lazy_static! {
                    static ref TEST_ENTITY_CMARK: PathBuf = PathBuf::from("/tmp/test/entity.md");
                };
                TEST_ENTITY_CMARK.as_path()
            }
            Self::TestEntityRust => {
                lazy_static::lazy_static! {
                    static ref TEST_ENTITY_RUST: PathBuf = PathBuf::from("/tmp/test/entity.rs");
                };
                TEST_ENTITY_RUST.as_path()
            }
        }
    }
Represent the content origin as [path](std::path::PathBuf).

For unit and integration tests, two additional hardcoded variants are
available, which resolve to static paths: `TestEntityRust` variant
becomes `/tmp/test/entity.rs`, `TestEntityCommonMark` variant becomes
`/tmp/test/entity.md`.
doc-chunks/src/chunk.rs