Address review comments for operator conditions helpers

[varshaprasad96]

Description of the change:
This PR does the following:

• Move getOperatorNamespace() to a seprate utils package.
• Allow namespace to be set locally with an env variable.
• Modify the order of tests and add godoc to env variables.
• Remove redundant code.

Motivation for the change:
Follow-up #41

[coveralls]

Pull Request Test Coverage Report for Build 395031807

• 12 of 16 (75.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.3%) to 77.363%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/utils/utils.go	8	12	66.67%

Totals
Change from base Build 373437473:	0.3%
Covered Lines:	311
Relevant Lines:	402

---

💛 - Coveralls

[jmrodri]

Just a few questions

[joelanford]

Not to throw a wrench into things, but another potential way to go with this library is to make an interface like this:

type Upgradabler interface {
    // GetUpgradable gets the Upgradable condition on the operator's 
	// OperatorCondition. It returns an error if there are problems getting
	// the OperatorCondition object or if the Upgradable condition does not
	// exist.
    GetUpgradable(context.Context) (*metav1.Condition, error)

    // SetUpgradable sets the Upgradable condition on the operator's 
	// OperatorCondition to the status s. It returns an error if there
	// are problems getting or updating the OperatorCondition object.
    SetUpgradable(context.Context, metav1.ConditionStatus, ...Option) error
}

// Option is a function that applies a change to a condition
// This can be used to set optional condition fields, like reasons
// and messages.
type Option func(*metav1.Condition)

func WithReason(reason string) Option {
	return func(c *metav1.Condition) {
		c.Reason = reason
	}
}

func WithMessage(message string) Option {
	return func(c *metav1.Condition) {
		c.Message = message
	}
}

And then we could have an implementation that internally looks up (and caches) the namespaced name, and then fetches the current OperatorCondition, sets (or gets) the condition value, and then performs an update (if the value changed).

This way, a user wouldn't have to import operator-framework/api or really even know about the OperatorCondition type, and it would make it much easier for operator authors to mock an implementation of this and write tests around their upgrade logic.

[varshaprasad96]

@estroz @jmrodri : Made the suggested changes, please have a look

[estroz]

Alternative approach:
Instead of doing

func GetOperatorNamespace(readNamespace func() ([]byte, error)) (string, error) {
	...
}

var readNamespace = func() ([]byte, error) {
	return ioutil.ReadFile("/var/run/secrets/kubernetes.io/serviceaccount/namespace")
}

func foo() {
	_, _ = GetOperatorNamespace(readNamespace)
}

you could do

func GetOperatorNamespace() (string, error) {
	...
}

var readNamespace = GetOperatorNamespace()

func foo() {
	_, _ = readNamespace()
}

which is a little less confusing and still mockable in tests in a similar way as to how you have it now:

var _ = Describe("test namespace", func() {
	// This
	readNamespace = func() (string, error) {
		return "some-ns"
	}
	// Or this
	f := func(s string) (func() (string, error)) {
		return func() (string, error) { return s, nil }
	}
	readNamespace = f("some-ns")
}

[varshaprasad96]

Since go would not allow var readNamespace = GetOperatorNamespace() when GetOperatorNamespace() is not an anonymous function, have declared it as a variable here. We would still need readSAFile to test this function.

[estroz]

/lgtm

[estroz]

/approve

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