Add automated integration and unit tests

[Kidswiss]

Summary

As K8up developer
I want automated whitebox tests of K8up internals
So that I can contribute tested features and changes to ensure quality and avoid accidental breaking changes

Context

Currently it's unclear if there's a distinction between integration tests and unit tests.
A potential distinction could be:

• Integration tests: all tests that require a K8s Api server (envtest)
• Unit tests: function tests that can run without API server, to test microfunctions in code.

But in all honesty, it doesn't really make a difference. However, some IDEs may have difficulties to debug tests when envtest is running if those only run in Makefile.

Out of Scope

• Implement e2e tests
• Implement tests that are part of (w)restic itself
• Achieve a certain code coverage threshold. code coverage as metric doesn't say much about actual quality.

Further links

• Tutorial
• Inspiration in Espejo

Acceptance criteria

Given a K8up PR
When I push code into a feature branch
Then GitHub should run automated tests and indicate to code authors and reviewers of passing or failing tests

Implementation Ideas

• The Operator-SDK scaffolds tests with envtest, a library that runs a minimal Kubernetes API server in memory where we get full support for Kubernetes client operations

[ccremer]

#152 sets the foundation for this case, at least locally (not in GH action yet). I was already able to run it:

$ make integration_test
/home/chris/go/bin/controller-gen object:headerFile="hack/boilerplate.go.txt" paths="./..."
go fmt ./...
go vet ./...
/home/chris/go/bin/controller-gen "crd:trivialVersions=true" rbac:roleName=manager-role webhook paths="./..." output:crd:artifacts:config=config/crd/bases
2020/11/25 13:27:40 Reading file config/crd/bases/backup.appuio.ch_prebackuppods.yaml
2020/11/25 13:27:40 Removed 'protocol' in line 1275
2020/11/25 13:27:40 Removed 'protocol' in line 3593
2020/11/25 13:27:40 Writing new file to config/crd/bases/backup.appuio.ch_prebackuppods.yaml
test -f /home/chris/Documents/source/vshn/k8up/testbin/setup-envtest.sh || curl -sSLo /home/chris/Documents/source/vshn/k8up/testbin/setup-envtest.sh https://raw.githubusercontent.com/kubernetes-sigs/controller-runtime/master/hack/setup-envtest.sh
source /home/chris/Documents/source/vshn/k8up/testbin/setup-envtest.sh; fetch_envtest_tools /home/chris/Documents/source/vshn/k8up/testbin; setup_envtest_env /home/chris/Documents/source/vshn/k8up/testbin; go test -tags=integration -v ./... -coverprofile cover.out
Using cached envtest tools from /home/chris/Documents/source/vshn/k8up/testbin
setting up env vars
?   	github.com/vshn/k8up	[no test files]
?   	github.com/vshn/k8up/api/v1alpha1	[no test files]
?   	github.com/vshn/k8up/constants	[no test files]
=== RUN   TestAPIs
Running Suite: Controller Suite
===============================
Random Seed: 1606307262
Will run 0 of 0 specs



Ran 0 of 0 Specs in 7.326 seconds
SUCCESS! -- 0 Passed | 0 Failed | 0 Pending | 0 Skipped
--- PASS: TestAPIs (7.33s)
PASS
coverage: 0.0% of statements
ok  	github.com/vshn/k8up/controllers	7.337s	coverage: 0.0% of statements
=== RUN   TestExecutor
Running Suite: Executor Suite
=============================
Random Seed: 1606307262
Will run 3 of 3 specs

•••
Ran 3 of 3 Specs in 0.001 seconds
SUCCESS! -- 3 Passed | 0 Failed | 0 Pending | 0 Skipped
--- PASS: TestExecutor (0.00s)
PASS
coverage: 17.2% of statements
ok  	github.com/vshn/k8up/executor	0.014s	coverage: 17.2% of statements
?   	github.com/vshn/k8up/handler	[no test files]
?   	github.com/vshn/k8up/job	[no test files]
?   	github.com/vshn/k8up/observer	[no test files]
?   	github.com/vshn/k8up/prebackup	[no test files]
?   	github.com/vshn/k8up/queue	[no test files]
?   	github.com/vshn/k8up/scheduler	[no test files]

[ccremer]

@Kidswiss I have refined this issue. Please review

[tobru]

As discussed in today's Tarazed sync we'll close this issue in favor of the outcome of the discussion in #231. We'll create appropriate individual issues to increase test coverage.