I will log to stderr here.
# this should fail
not ok 1 should be equal
    file:   <FILE_PATH>/failure.js
    line:   5
    column: 5
    stack:  
      - getCaller (<FILE_PATH>/tap-assert.js:<LINE:COL>)
      - assert (<FILE_PATH>/tap-assert.js:<LINE:COL>)
      - Function.equal (<FILE_PATH>/tap-assert.js:<LINE:COL>)
      - Test._testAssert [as equal] (<FILE_PATH>/tap-test.js:<LINE:COL>)
      - Test.<anonymous> (<FILE_PATH>/failure.js:<LINE:COL>)
      - Test.emit (events.js:<LINE:COL>)
      - Test.emit (<FILE_PATH>/tap-test.js:<LINE:COL>)
      - GlobalHarness.Harness.process (<FILE_PATH>/tap-harness.js:<LINE:COL>)
      - process._tickCallback (node.js:<LINE:COL>)
      - Function.Module.runMain (module.js:<LINE:COL>)
    found:  true
    wanted: false
  ...

Assert: "should be equal", 
	 found: true 
	wanted: false
	<FILE_PATH>/failure.js:5