Unit.js , Mocha example.js fails 0 passed

I am just learning Unit.js with mocha. I am following the steps at: http://ift.tt/2cuf8n7 . I have installed mocha and am running the "example.js" script. The script fails with

$ mocha example.js

0 passing (1ms)

Running the example.js in with -full-trace I get:

$ mocha example.js -full-trace

C:\Users\rball\AppData\Roaming\npm\node_modules\mocha\lib\utils.js:652
        throw new Error("cannot resolve path (or pattern) '" + path + "'");
        ^

Error: cannot resolve path (or pattern) '-t'
    at Object.lookupFiles (C:\Users\rball\AppData\Roaming\npm\node_modules\mocha\lib\utils.js:652:15)
    at C:\Users\rball\AppData\Roaming\npm\node_modules\mocha\bin\_mocha:326:30
    at Array.forEach (native)
    at Object.<anonymous> (C:\Users\rball\AppData\Roaming\npm\node_modules\mocha\bin\_mocha:325:6)
    at Module._compile (module.js:435:26)
    at Object.Module._extensions..js (module.js:442:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:311:12)
    at Function.Module.runMain (module.js:467:10)
    at startup (node.js:134:18)
    at node.js:961:3

I am running this with cygwin64. and running in the directory: /home/rball/test

the example.js is:

// load Unit.js module
var test = require('../node_modules/unit.js');
// just for example of tested value
var example = 'hello';
// assert that example variable is a string
test.string(example);
// or with Must.js
test.must(example).be.a.string();
// or with assert

The unit.js is in the node_modules directory.

The error in the full trace output is baffling since I am not aware of any path with a "-t" in it.

What am I missing?

Thanks for your help