Function test_spare_capacity

src/buffer.rs:430–456

()

    #[cfg(not(windows))]
    #[test]
    fn test_spare_capacity() {
        use crate::io::read;
        use std::io::{Seek, SeekFrom};

        // We need to obtain input stream with contents that we can compare
        // against, so open our own source file.
        let mut input = std::fs::File::open("src/buffer.rs").unwrap();

        let mut buf = Vec::with_capacity(64);
        let nread = read(&input, spare_capacity(&mut buf)).unwrap();
        assert_eq!(nread, buf.capacity());
        assert_eq!(nread, buf.len());
        assert_eq!(
            &buf[..58],
            b"//! Utilities for functions that return data via buffers.\n"
        );
        buf.clear();
        input.seek(SeekFrom::End(-1)).unwrap();
        let nread = read(&input, spare_capacity(&mut buf)).unwrap();
        assert_eq!(nread, 1);
        assert_eq!(buf.len(), 1);
        buf.clear();
        input.seek(SeekFrom::End(0)).unwrap();
        let nread = read(&input, spare_capacity(&mut buf)).unwrap();
        assert_eq!(nread, 0);
        assert!(buf.is_empty());
    }
}