process.exit before console buffer flushed in Windows

[coder-mike]

Symptoms

If any test fails, not all the console output is shown (console output is truncated).

Problem does not show up in standard Windows cmd, but does show up if tests are run from Cygwin or within Sublime Text build system. In Cygwin, if the output is piped to a file instead of being displayed on the console then all the results show in the file, even though they did not show in the console when not piped.

Environment

• nodeunit 0.9.0,
• node 0.10.17
• Windows 7

Minimal Example

I have the following test file, tests.js:

for (var i = 0; i < 30; i++)
    console.log('' + i);

exports.dummy = function(test) {
    test.fail();
    test.done();
}

Running from Cygwin, the result is:

$ nodeunit tests.js
0

(I.e., only the first console.log appears). But if I remove the test.fail line then all the output appears.

Cause

My guess of the cause is given in the title. It appears that under different circumstances, sometimes the node console is asynchronous (perhaps due to the way Windows pipes work, I'm not sure), and doesn't flush the output after every write. When a test fails, line 130 in nodeunit/nodeunit process.exit(1); seems to recognize the error and exit the process, but process.exit does not seem to always wait for the console output to be received by the terminal. To confirm this hypothesis, if I remove the process.exit line, then the output is displayed correctly.

Solution

A work-around seems to be to change lines 128-132 to the following:

testrunner.run(files, options, function(err) {
    if (err) {
        process.on('exit', function() {
            process.exit(1);
        });
    }
});

This seems to produce the correct error code for the process and also show all the output. I don't know if there are any other side effects of not ending the process immediately in the callback function.

[gagern]

I've encountered similar issues in another project. There the pipe was to some other node process, not to the console, but the effect is the same. In CindyJS/CindyJS@46aeba3 I've addressed that using a process.once('beforeExit', …) hook. In my opinion that event better captures the goal of executing the code once the event loop has drained.