async_test.js

process.mixin(require('sys'));

valid_modes = ["r", "w", "a"];

var File = {
  open: function (filename, mode) { return function (callback) {
    debug("in open closure");
    mode = mode || "w";
    if (valid_modes.indexOf(mode) < 0) {
      throw new Error("Invalid file mode " + JSON.stringify(mode));
    }
    if (!filename) {
      throw new Error("Must specify a filename");
    }
    setTimeout(function () {
      if (filename !== "test.txt") {
        throw new Error("File not found " + filename);
      }
      callback(1)
    }, 100);
  }},

};

try {
  debug("About to call open (no errors expected)");
  File.open("test.txt")(function (fd) {
    debug("Done, no errors");
  });
} catch(e) {
  debug("Block 1: " + e.stack);
}

try {
  debug("About to call open (immediete error expected)");
  File.open("test.txt", "z")(function (fd) {
    debug("Done, no errors");
  });
} catch(e) {
  debug("Block 2: " + e.stack);
}

try {
  debug("About to call open (delayed error expected)");
  File.open("badname.txt")(function (fd) {
    debug("Done, no errors");
  });
} catch(e) {
  debug("Block 3: " + e.stack);
}

output.txt

DEBUG: About to call open (no errors expected)
DEBUG: in open closure
DEBUG: About to call open (immediete error expected)
DEBUG: in open closure
DEBUG: Block 2: Error: Invalid file mode "z"
    at /Users/tim/Code/jack/async.js:10:13
    at Object. (/Users/tim/Code/jack/async.js:36:28)
    at [object Object]. (node.js:932:23)
    at [object Object].emitSuccess (node.js:244:15)
    at [object Object]. (node.js:657:21)
    at [object Object].emitSuccess (node.js:244:15)
    at node.js:514:29
    at node.js:989:9
DEBUG: About to call open (delayed error expected)
DEBUG: in open closure
DEBUG: Done, no errors
Error: File not found badname.txt
    at Timer. (/Users/tim/Code/jack/async.js:17:15)
    at node.js:989:9