test_verify1.py 文件源码

def test_FILE_stored_in_stdout():
    if not sys.platform.startswith('linux'):
        py.test.skip("likely, we cannot assign to stdout")
    ffi = FFI()
    ffi.cdef("int printf(const char *, ...); FILE *setstdout(FILE *);")
    lib = ffi.verify("""
        #include <stdio.h>
        FILE *setstdout(FILE *f) {
            FILE *result = stdout;
            stdout = f;
            return result;
        }
    """)
    import os
    fdr, fdw = os.pipe()
    fw1 = os.fdopen(fdw, 'wb', 256)
    old_stdout = lib.setstdout(fw1)
    try:
        #
        fw1.write(b"X")
        r = lib.printf(b"hello, %d!\n", ffi.cast("int", 42))
        fw1.close()
        assert r == len("hello, 42!\n")
        #
    finally:
        lib.setstdout(old_stdout)
    #
    result = os.read(fdr, 256)
    os.close(fdr)
    # the 'X' might remain in the user-level buffer of 'fw1' and
    # end up showing up after the 'hello, 42!\n'
    assert result == b"Xhello, 42!\n" or result == b"hello, 42!\nX"