Enable cache mutation detector in unit tests

Signed-off-by: Monis Khan <mok@vmware.com>

internal/controller/controller_test.go

@@ -0,0 +1,29 @@
+// Copyright 2020 the Pinniped contributors. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package controller
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"k8s.io/client-go/tools/cache"
+)
+
+func TestCacheMutationDetectorEnabled(t *testing.T) {
+	// this is a bit of simplistic test to check if we have a real cache mutation detector.
+	// if we actually start mutating an informer cache in this test, the test will almost
+	// always fail because the go race detector will see the mutation.
+	// the cache mutation detector will certainly make certain races more common and thus
+	// easily detected by the race detector, but its real use is against a compiled binary
+	// such as pinniped-server running in a pod - that binary has no race detector at runtime.
+
+	c := cache.NewCacheMutationDetector("test pinniped")
+
+	type isRealCacheMutationDetector interface {
+		CompareObjects() // this is brittle, but this function name has never changed...
+	}
+
+	_, ok := c.(isRealCacheMutationDetector)
+	require.Truef(t, ok, "%T is not a real cache mutation detector", c)
+}