solcover fail to generate test coverage with my simple add contract - test-coverage

Question

I want to use solcover to generate test coverage of my contract.
https://github.com/JoinColony/solcover
I test it with the simple one:
contract Add {
function Add() {
}
function sum(uint x, uint y) returns (uint) {
return (x+y);
}
}
And here is my test code:
contract('Add', function(accounts) {
it("should return 5 when add 2 and 3", function() {
var add = Add.deployed();
return add.sum.call(2,3).then(function(res){
assert.equal(res.valueOf(), 5, "add result is 5");
});
});
});
But there are some errs when compile it.
Add.sol:2:1: Warning: Source file does not specify required compiler version!Consider adding "pragma solidity ^0.4.6
contract Add {
^
Spanning multiple lines.
Compilation failed. See above.
fs.js:549
Then i add compile version like this:
pragma solidity ^0.4.6;
contract Add {
function Add() {
}
function sum(uint x, uint y) returns (uint) {
return (x+y);
}
}
And now it pass the compile. But this time I got the error:
cp: no such file or directory: ./../originalContracts/Migrations.sol
rm: no such file or directory: ./allFiredEvents
Compiling Add.sol...
Contract: Add
✓ should return 5 when add 2 and 3
1 passing (15s)
fs.js:549
return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
^
Error: ENOENT: no such file or directory, open './allFiredEvents'
at Error (native)
at Object.fs.openSync (fs.js:549:18)
at Object.fs.readFileSync (fs.js:397:15)
at Object.<anonymous> (/Users/maiffany/graduate/mytest/solcover/runCoveredTests.js:60:13)
at Module._compile (module.js:409:26)
at Object.Module._extensions..js (module.js:416:10)
at Module.load (module.js:343:32)
at Function.Module._load (module.js:300:12)
at Function.Module.runMain (module.js:441:10)
at startup (node.js:139:18)
And in the runCoveredTests.js I found this:
55:shell.cp("./../originalContracts/Migrations.sol",./../contracts/Migrations.sol");
56:
57:shell.rm('./allFiredEvents'); //Delete previous results
58:shell.exec('truffle test --network coverage');
59:
60:events = fs.readFileSync('./allFiredEvents').toString().split('\n')
I guess maybe it is this command that generate file "allFiredEvents". So i try this in my command line:
truffle test --network coverage
Compiling Add.sol...
Contract: Add
✓ should return 5 when add 2 and 3
1 passing (24s)
But i still can't find the file "allFiredEvents".
So where did i get wrong?