So:
```
        rfs = self.repoPrx.file(self.repo_filename, "rw") #create empty file
        rfs.write([], 0, 0)
        assert rfs.size() == 0
        rfs.close()
```
should be okay? Whereas,
```
        # Without a single write, no file is produced
        rfs = self.repoPrx.file(self.repo_filename, "rw") #create empty file
        assert rfs.size() == 0
        rfs.close()
```
should raise an exception on `rfs.size()`? I.e. is it the `rfs.write([],0,0)` that causes the underlying file to exist or the `rfs.close()` following a write? In fact is the comment `#create empty file` really at the right point?