Go test infrastructure

[nirs]

The go tests require running imageio server serving an empty 6g image.

Currently running the Go tests requires lot of manual steps:

1. Start another shell
2. Build

make

3. Run test server

./ovirt-imageio -c examples

4. Start another shell and add a ticket

./ovirt-imageioctl add-ticket -c examples examples/nbd.json

5. Create empty qcow2 image

qemu-img create -f qcow2 empty.qcow2 6g

6. Run qemu-nbd serving the ticket

qemu-nbd -r -t -e8 -f qcow2 empty.qcow2 -k /tmp/nbd.sock

7. Run the tests

$ go test -v ./...
?   	ovirt.org/ovirt-img	[no test files]
=== RUN   TestNbdSize
--- PASS: TestNbdSize (0.00s)
=== RUN   TestNbdExtents
--- PASS: TestNbdExtents (0.00s)
PASS
ok  	ovirt.org/ovirt-img/nbd	0.004s
?   	ovirt.org/ovirt-img/qemuimg	[no test files]

What we need is infrastructure like the python tests:

• running imageio server per test or per module
• easy way to add tickets - helper running ovirt-imageioctl?
• easy way to create test image, so we can test more interesting images, not only empty images
• easy way to run qemu-nbd, serving a test image, like python qemu_nbd.run()