Fix race conditions in unit tests

The tests were not correct to begin with, and a change in the
`assert.Eventually` implementation exposed the bug:
stretchr/testify#1427

Signed-off-by: Antonin Bas <[email protected]>

Author: antoninbas

pkg/agent/ipassigner/linkmonitor/link_monitor_linux_test.go

@@ -277,6 +277,8 @@ func Test_linkMonitor_listAndWatchLinks(t *testing.T) {
 					for _, l := range tt.eventHandlers {
 						assert.Equal(t, l.expectedLinkEvents, l.getReceivedLinkEvents())
 					}
+					d.mutex.RLock()
+					defer d.mutex.RUnlock()
 					assert.ElementsMatch(t, tt.expectedExistingLinks, d.linkNames.UnsortedList())
 				},
 				1*time.Second, 100*time.Millisecond, "timeout waiting for link events",

pkg/apiserver/registry/system/supportbundle/rest.go

@@ -111,7 +111,11 @@ type supportBundleREST struct {
 	mode         string
 	statusLocker sync.RWMutex
 	cancelFunc   context.CancelFunc
-	cache        *systemv1beta1.SupportBundle
+	// cache stores the "current" or most recent SupportBundle resource. Because Get returns
+	// this value directly, it is important for the supportBundleREST implementation *not* to
+	// mutate fields in the SupportBundle object once it has been assigned to cache, in order to
+	// ensure thread-safety. Otherwise, we would have a race with Get callers.
+	cache *systemv1beta1.SupportBundle
 
 	ovsCtlClient ovsctl.OVSCtlClient
 	aq           agentquerier.AgentQuerier
@@ -154,8 +158,11 @@ func (r *supportBundleREST) Create(ctx context.Context, obj runtime.Object, _ re
 			r.statusLocker.Lock()
 			defer r.statusLocker.Unlock()
 			if err != nil {
-				klog.Errorf("Error when collecting supportBundle: %v", err)
-				r.cache.Status = systemv1beta1.SupportBundleStatusNone
+				klog.ErrorS(err, "Error when collecting supportBundle")
+				r.cache = &systemv1beta1.SupportBundle{
+					ObjectMeta: metav1.ObjectMeta{Name: r.mode},
+					Status:     systemv1beta1.SupportBundleStatusNone,
+				}
 				return
 			}
 			select {