Added if condition to check for embedded resources in pdf and raise error if file not found

[duskybomb]

Figured it out
After merge we can close #16

[m3nu]

This looks very complicated. Why is test code in the main function? I'm not sure this is the best solution.

[duskybomb]

I don't know if you will approve this, but for testing file_doesn't_exist case I had to move checking to __new__ so that I can return something and test doesn't fail because of Error we are raising.

[m3nu]

This doesn't look right to me. You can look at Alexis' original repo on how he did the checking.

[duskybomb]

The checking part was easy and straight forward see here, but I had to do this to enable unittest to verify that class FacturX is raising an Error.

[m3nu]

You can't change the main code just to enable tests. I'm sure there is another way.

[duskybomb]

I did a lot of research and couldn't find any other. The reason for the change is, we cannot assert (or do anything) after an error is raised. And since we will be enabling CI in future, we need either the test to pass or remove this check(normal check without changing main code).

[m3nu]

You can look at this SO question to get an idea on how to test for correct Exceptions.

[duskybomb]

Obviously I did and implemented it, but the solution is wrong. It is saying something completely different and doesn't apply here.

[duskybomb]

Check this https://stackoverflow.com/a/31918982

[m3nu]

Maybe choose another issue to work on. I'll tackle this one later. Thanks anyways.

[m3nu]

What's wrong with this solution that seems to work well enough?

    def test_input_error(self):
        with self.assertRaises(TypeError):
            FacturX('non-existant.pdf')

[duskybomb]

Now it seems to work, strange. My bad.

But this doesn't

import mymod

class MyTestCase(unittest.TestCase):
    def test1(self):
        self.assertRaises(SomeCoolException, mymod.myfunc)

[duskybomb]

Yeah so we need to make this change to raise the FileNotFoundError this commit and hence tweak the test a little