Add ScheduledJob to validation

[johscheuer]

Fix the tests for release-1.4 in #1123 @janetkuo added a file for a ScheduledJob this results in a fail:

=== RUN   TestExampleObjectSchemas
--- FAIL: TestExampleObjectSchemas (0.02s)
    examples_test.go:293: ../docs/user-guide/sj.yaml: sj does not have a test case defined

See #1067 for example. I added the file and a validation for the ScheduledJob.

---

This change is

[johscheuer]

One question in the tests the following validation step is defined:

    case *batch.Job:
        if t.Namespace == "" {
            t.Namespace = api.NamespaceDefault
        }
        // Job needs generateSelector called before validation, and job.Validate does this.
        // See: https://github.com/kubernetes/kubernetes/issues/20951#issuecomment-187787040
        t.ObjectMeta.UID = types.UID("fakeuid")
        errors = job.Strategy.Validate(nil, t)

We could replace the last line with:

errors = batch_validation.ValidateJob(t)

First attempt resulted in a Fail:

    --- FAIL: TestExampleObjectSchemas (0.01s)
        examples_test.go:326: ../docs/user-guide/job.yaml did not validate correctly: [spec.selector: Required value spec.template.metadata.labels: Invalid value: null: `selector` does not match template `labels`]
        examples_test.go:326: ../docs/user-guide/jobs/work-queue-1/job.yaml did not validate correctly: [spec.selector: Required value spec.template.metadata.labels: Invalid value: null: `selector` does not match template `labels`]
        examples_test.go:326: ../docs/user-guide/jobs/work-queue-2/job.yaml did not validate correctly: [spec.selector: Required value spec.template.metadata.labels: Invalid value: null: `selector` does not match template `labels`]
FAIL

[caesarxuchao]

LGTM. Thanks @johscheuer.

@pwittrock can we merge this? It's fixing a test that affects all PRs.

[caesarxuchao]

@johscheuer the validation error you mentioned is expected (see https://github.com/kubernetes/kubernetes/blob/master/pkg/apis/batch/validation/validation.go#L74). In real cluster, the selector and labels will be automatically generated by the server if user doesn't specify them in config. We should mimic this behavior in test.

scheduledjob validation does not verify the selector matches labels, which is a bug IMO, we should fix it. @janetkuo @erictune

[janetkuo]

The test file wasn't in the release-1.4 when the PR #1123 was merged. This change is the same as the one I had here 91a40c0

[janetkuo]

scheduledjob validation does not verify the selector matches labels, which is a bug IMO, we should fix it.

scheduledjob doesn't have selectors

[caesarxuchao]

Thanks @janetkuo !