Add ExpectError() to e2e test framework

There is a lot of gomega.Expect(err).To(gomega.HaveOccurred()) callers
which expect an error happens in e2e tests.
However these test code seems confusing because the code readers
need to take care of To() or NotTo() on each test scenario.
This adds ExpectError() for more readable test code.
In addition, this applies ExpectError() to e2e provisioning.go as a
sample.

Author: Kenichi Omichi

test/e2e/framework/util.go

@@ -2038,6 +2038,11 @@ func RandomSuffix() string {
 	return strconv.Itoa(r.Int() % 10000)
 }
 
+// ExpectError expects an error happens, otherwise an exception raises
+func ExpectError(err error, explain ...interface{}) {
+	gomega.Expect(err).To(gomega.HaveOccurred(), explain...)
+}
+
 // ExpectNoError checks if "err" is set, and if so, fails assertion while logging the error.
 func ExpectNoError(err error, explain ...interface{}) {
 	ExpectNoErrorWithOffset(1, err, explain...)

test/e2e/storage/testsuites/provisioning.go

@@ -484,7 +484,7 @@ func (t StorageClassTest) TestBindingWaitForFirstConsumerMultiPVC(claims []*v1.P
 	// Wait for ClaimProvisionTimeout (across all PVCs in parallel) and make sure the phase did not become Bound i.e. the Wait errors out
 	By("checking the claims are in pending state")
 	err = framework.WaitForPersistentVolumeClaimsPhase(v1.ClaimBound, t.Client, namespace, claimNames, 2*time.Second /* Poll */, framework.ClaimProvisionShortTimeout, true)
-	Expect(err).To(HaveOccurred())
+	framework.ExpectError(err)
 	verifyPVCsPending(t.Client, createdClaims)
 
 	By("creating a pod referring to the claims")