def METHOD_NAME(self):
    # If clang-format changes any lines, we want to fail-fast.
    # (Note the two spaces between #include and the double quote.)
    original_lines = ['#include  "nontrivial.h"\n']
    dut = IncludeFormatter("nontrivial.cc", readlines=original_lines)
    dut.format_includes()
    with self.assertRaisesRegex(Exception, 'not just a shuffle'):
        dut.rewrite_file()