Testing improvements

[nikhiljindal]

List of tasks:

• [ ] More extensive unit tests, especially for failure cases.
• [x] Code coverage: Measure code coverage for the repo and comment on open PRs with how much code coverage are they changing.
• [x] e2e tests: Add a script to run e2e tests and then run it periodically on test-infra.
• [x] Automated tests - unit and e2e tests that run on each PR in review

cc @csbell @G-Harmon

[nikhiljindal]

Our current test coverage stats:

k8s-multicluster-ingress/app/kubemci/cmd 0.436s  coverage: 39.9% of statements
k8s-multicluster-ingress/app/kubemci/pkg/gcp/backendservice      0.227s  coverage: 76.3% of statements
k8s-multicluster-ingress/app/kubemci/pkg/gcp/firewallrule        0.409s  coverage: 60.6% of statements
k8s-multicluster-ingress/app/kubemci/pkg/gcp/forwardingrule      0.279s  coverage: 47.8% of statements
k8s-multicluster-ingress/app/kubemci/pkg/gcp/healthcheck 0.243s  coverage: 81.3% of statements
k8s-multicluster-ingress/app/kubemci/pkg/gcp/loadbalancer        0.381s  coverage: 65.5% of statements
k8s-multicluster-ingress/app/kubemci/pkg/gcp/targetproxy 0.266s  coverage: 51.7% of statements
k8s-multicluster-ingress/app/kubemci/pkg/gcp/urlmap      0.313s  coverage: 43.0% of statements
k8s-multicluster-ingress/app/kubemci/pkg/gcp/utils       0.039s  coverage: 90.9% of statements

I would say average is ~50-60%. (least is 39% and max is 90%)

[nikhiljindal]

With https://github.com/GoogleCloudPlatform/k8s-multicluster-ingress/pull/62 and https://github.com/kubernetes/test-infra/pull/5373, we now have automated unit tests running on every pending PR.

[nikhiljindal]

With https://github.com/GoogleCloudPlatform/k8s-multicluster-ingress/pull/84, we now have a framework to run e2e tests. Next step is to run the e2e tests regularly as a prow job

[nikhiljindal]

We now have e2e tests running periodically on prow: https://k8s-testgrid.appspot.com/sig-multicluster-kubemci#kubemci-ingress-conformance. Unit tests are run on every PR and also periodically on prow.