Test for writing and reading a file starting with a BOM

STARTTEST
:so mbyte.vim
:set encoding=utf-8
:set fileencodings=ucs-bom,latin-1
:set ff=unix ffs=unix           " This changes the file for DOS and MAC
:" --- Write the test files
:/^latin-1$/+1w! Xtest0
:/^utf-8$/+1w! Xtest1
:/^utf-8-err$/+1w! Xtest2
:/^ucs-2$/+1w! Xtest3
:/^ucs-2le$/+1w! Xtest4
:" Need to add a NUL byte after the NL byte
:set bin
:e! Xtest4                      " Ignore change from setting 'ff'
o:set noeol
:w
:set ffs& nobinary              " Allow default test42.in format
:e #
:set ff=unix                    " Format for files to write
:/^ucs-4$/+1w! Xtest5
:/^ucs-4le$/+1w! Xtest6
:" Need to add three NUL bytes after the NL byte
:set bin
:e! Xtest6                      " ! for when setting 'ff' is a change
o:set noeol
:w
:set nobin
:e #
:"
:" --- Check that editing a latin-1 file doesn't see a BOM
:e! Xtest0
:redir! >test.out
:set fileencoding bomb?
:redir END
:set fenc=latin-1
:w >>test.out
:set bomb fenc=latin-1
:w! Xtest0x
:"
:" --- Check utf-8
:e! Xtest1
:redir >>test.out
:set fileencoding bomb?
:redir END
:set fenc=latin-1
:w >>test.out
:set fenc=utf-8
:w! Xtest1x
:"
:" --- Check utf-8 with an error (will fall back to latin-1)
:e! Xtest2
:redir >>test.out
:set fileencoding bomb?
:redir END
:set fenc=latin-1
:w >>test.out
:set fenc=utf-8
:w! Xtest2x
:"
:" --- Check ucs-2
:e! Xtest3
:redir >>test.out
:set fileencoding bomb?
:redir END
:set fenc=latin-1
:w >>test.out
:set fenc=ucs-2
:w! Xtest3x
:"
:" --- Check ucs-2le
:e! Xtest4
:redir >>test.out
:set fileencoding bomb?
:redir END
:set fenc=latin-1
:w >>test.out
:set fenc=ucs-2le
:w! Xtest4x
:"
:" --- Check ucs-4
:e! Xtest5
:redir >>test.out
:set fileencoding bomb?
:redir END
:set fenc=latin-1
:w >>test.out
:set fenc=ucs-4
:w! Xtest5x
:"
:" --- Check ucs-4le
:e! Xtest6
:redir >>test.out
:set fileencoding bomb?
:redir END
:set fenc=latin-1
:w >>test.out
:set fenc=ucs-4le
:w! Xtest6x
:"
:" --- Check the files written with BOM
:set bin
:e! test.out
:$r Xtest0x
:$r Xtest1x
:$r Xtest2x
:$r Xtest3x
:$r Xtest4x
:$r Xtest5x
:$r Xtest6x
:set nobin ff&               " Write the file in default format
:w! test.out
:qa!
ENDTEST

latin-1
�tin-1
utf-8
utf-8
utf-8-err
utf-8�rr
ucs-2
�cs-2
ucs-2le
�cs-2le
ucs-4
�ucs-4
ucs-4le
�ucs-4le