JSON reporter output appears in Debug Console and results not updated when writing output to stdout without newlines

void main() {
  test('foo', () {
    stdout.write('foo');
  });
}

Using writeln prevents the issue.

[jakemac53]

I looked into this a little bit, and chatted with @natebosch about it as well.

There are a few challenges involved generally, such as what to do if somebody writes arbitrary bytes, the fact that reporters can’t unconditionally import dart:io at all, etc. Also customizing things just for the json reporter also is not very clean to do and would require a fair bit of plumbing.

The general consensus we reached is as follows:

• Always override stdout/stderr, so we don’t break our output.
• Always convert Strings into normal print messages, probably using the line splitter to only send messages when we get a newline (this would be a bit of a behavior change if we wait for newlines). We may prefix the strings with Stdout: and/or Stderr: etc.
• For raw bytes, first attempt to decode them with the current encoding.
  • If we can, then treat the result like a normal String.
  • If we can’t, then just emit either the base 64 encoded bytes or a character or message indicating an invalid string.
• For the rest of the Stdout api:
  • hasTerminal: always returns false
  • terminalColumns: always throws
  • terminalLines: always throws
  • nonBlocking: returns this
  • addError: add the error to the error stream controller

If people are relying on the existing behavior in some way, we can address that on a case by case basis, but most likely the answer will just be that they should use their own IOOverrides to get different behavior if needed.

[DanTup]

Sounds reasonable to me. Since it sounds like this can all be solved in pkg:test, I’ve opened https://github.com/dart-lang/test/issues/1749 and will close this one.