Add a unit test for config_controller.go

Add a unit test for config_controller.go to test the case that when a new type is added to HNCConfiguration singleton, the corresponding object reconciler can be created correctly.

This PR also moves shared helper functions from each controller test files to a common file.

Design doc: http://bit.ly/hnc-type-configuration
Issue: kubernetes-retired#411

incubator/hnc/pkg/controllers/config_controller_test.go

@@ -0,0 +1,52 @@
+package controllers_test
+
+import (
+	"context"
+	"time"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("HNCConfiguration", func() {
+	ctx := context.Background()
+
+	var (
+		fooName string
+		barName string
+	)
+
+	BeforeEach(func() {
+		fooName = createNS(ctx, "foo")
+		barName = createNS(ctx, "bar")
+	})
+
+	AfterEach(func() {
+		// Change current singleton back to the default value.
+		Eventually(func() error {
+			c := getHNCConfig(ctx)
+			return resetHNCConfigToDefault(ctx, c)
+		}).Should(Succeed())
+	})
+
+	It("should propagate objects whose types have been added to HNCConfiguration", func() {
+		setParent(ctx, barName, fooName)
+		makeSecret(ctx, fooName, "foo-sec")
+
+		// Wait 1 second to give "foo-sec" a chance to be propagated to bar, if it can be propagated.
+		time.Sleep(1 * time.Second)
+		// Foo should have "foo-sec" since we created it there.
+		Eventually(hasSecret(ctx, fooName, "foo-sec")).Should(BeTrue())
+		// "foo-sec" is not propagated to bar because Secret hasn't been configured in HNCConfiguration.
+		Eventually(hasSecret(ctx, barName, "foo-sec")).Should(BeFalse())
+
+		Eventually(func() error {
+			c := getHNCConfig(ctx)
+			return addSecretToHNCConfig(ctx, c)
+		}).Should(Succeed())
+
+		// "foo-sec" should now be propagated from foo to bar.
+		Eventually(hasSecret(ctx, barName, "foo-sec")).Should(BeTrue())
+		Expect(secretInheritedFrom(ctx, barName, "foo-sec")).Should(Equal(fooName))
+	})
+})

incubator/hnc/pkg/controllers/hierarchy_controller_test.go

@@ -3,7 +3,6 @@ package controllers_test
 import (
 	"context"
 	"fmt"
-	"math/rand"
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -386,41 +385,6 @@ func updateHierarchy(ctx context.Context, h *api.HierarchyConfiguration) {
 	}
 }
 
-// createNSName generates random namespace names. Namespaces are never deleted in test-env because
-// the building Namespace controller (which finalizes namespaces) doesn't run; I searched Github and
-// found that everyone who was deleting namespaces was *also* very intentionally generating random
-// names, so I guess this problem is widespread.
-func createNSName(prefix string) string {
-	suffix := make([]byte, 10)
-	rand.Read(suffix)
-	return fmt.Sprintf("%s-%x", prefix, suffix)
-}
-
-// createNSWithLabel has similar function to createNS with label as additional parameter
-func createNSWithLabel(ctx context.Context, prefix string, label map[string]string) string {
-	nm := createNSName(prefix)
-
-	// Create the namespace
-	ns := &corev1.Namespace{}
-	ns.SetLabels(label)
-	ns.Name = nm
-	Expect(k8sClient.Create(ctx, ns)).Should(Succeed())
-	return nm
-}
-
-// createNS is a convenience function to create a namespace and wait for its singleton to be
-// created. It's used in other tests in this package, but basically duplicates the code in this test
-// (it didn't originally). TODO: refactor.
-func createNS(ctx context.Context, prefix string) string {
-	nm := createNSName(prefix)
-
-	// Create the namespace
-	ns := &corev1.Namespace{}
-	ns.Name = nm
-	Expect(k8sClient.Create(ctx, ns)).Should(Succeed())
-	return nm
-}
-
 func getLabel(ctx context.Context, from, label string) func() string {
 	return func() string {
 		ns := getNamespace(ctx, from)