tests: Add helper functions

[jodh-intel]

Add various helper functions to allow the easy creation of
virtcontainers objects and the manipulation of OCI resources:

func newTestCmd() vc.Cmd
func newTestContainerConfig(dir string) vc.ContainerConfig
func newTestHypervisorConfig(dir string, create bool) (vc.HypervisorConfig, error)
func newTestPodConfigNoop(dir string, create bool) (vc.PodConfig, error)
func newTestRuntimeConfig(dir, consolePath string, create bool) (oci.RuntimeConfig, error)

func createOCIConfig(bundleDir string) error
func makeOCIBundle(bundleDir string) error
func readOCIConfigFile(configPath string) (oci.CompatOCISpec, error)
func writeOCIConfigFile(spec oci.CompatOCISpec, configPath string) error

func runCommandFull(args []string, includeStderr bool) (string, error)

Fixes #451.

Signed-off-by: James O. D. Hunt james.o.hunt@intel.com

[coveralls]

Coverage increased (+0.2%) to 55.839% when pulling f2e6d08 on jodh-intel:add-test-utility-funcs into 175ac6a on clearcontainers:master.

[sboeuf]

According to the commit message, "easy creation of virtcontainers objects and the manipulation of OCI resources", don't you think this is something that should live in virtcontainers repo ?

[jodh-intel]

Well, some of these functions actually do live in vc already. But they are private to the virtcontainers tests.

So, we either make them public and move them out of the test files in virtcontainers, or implement our own minimal set as I've done on this PR.

[grahamwhaley]

OK, I've not studied in detail or tried it out, but the notion and a quick scan of the code:
lgtm

CI seems to be taking a while here....

[grahamwhaley]

and there we go. @sboeuf if you are happy, go ahead and merge etc.

[sboeuf]

@jodh-intel ok fair enough.
LGTM