capture_begin

fn capture_begin()

use io::{capture_begin};

Starts keeping this thread’s stdout and stderr writes in memory instead of writing them, until the matching capture_end().

Captures nest: each capture_end() closes the innermost one. Use it in tests to check what code prints. Threads spawned while capturing write to their own output. A capture still open when a test case ends goes to that case’s output.

Examples#

use io::{capture_begin, capture_end, stdout, write};
use string::{to_bytes};
use tests::assert;
capture_begin();
let _ = write(stdout(), to_bytes("hi\n"));
let (out, err) = capture_end();
assert!(out == "hi\n" && err == "");

See also#

• io::capture_end
• stdin: Returns a new stream on the process’s standard input.
• stdout: Returns a new stream on the process’s standard output.
• stderr: Returns a new stream on the process’s standard error.
• open: Opens the file at path with mode and returns a stream on it.
• close: Closes s.
• read: Reads bytes from s into the front of buf without waiting.
• write: Writes bytes from buf to s without waiting and returns how many were written.