== should keep an unparseable line verbatim instead of failing the whole file ==
FROM alpine
USER
RUN echo   hi

[expect]
FROM alpine
USER
RUN echo hi

== should keep a bare instruction keyword ==
LABEL

[expect]
LABEL

== should keep a COPY with too few arguments ==
COPY a

[expect]
COPY a

== should keep a FROM with trailing junk ==
FROM x y

[expect]
FROM x y

== should keep a non-keyword line ==
123 abc

[expect]
123 abc
