fix: avoid race caused by klog.InitFlags in utils_test

Without this fix, running `go test -race -count 10` causes this failure:

/var/folders/py/rwp4m4k977l9stj_f2kqrmxw000_5c/T/go-build3764188957/b001/csi-common.test flag redefined: log_dir
--- FAIL: TestLogGRPC (0.00s)
panic: /var/folders/py/rwp4m4k977l9stj_f2kqrmxw000_5c/T/go-build3764188957/b001/csi-common.test flag redefined: log_dir [recovered]
	panic: /var/folders/py/rwp4m4k977l9stj_f2kqrmxw000_5c/T/go-build3764188957/b001/csi-common.test flag redefined: log_dir

goroutine 70 [running]:
testing.tRunner.func1.2({0x17a37e0, 0xc0000b4180})
	/usr/local/Cellar/go/1.18.5/libexec/src/testing/testing.go:1389 +0x366
testing.tRunner.func1()
	/usr/local/Cellar/go/1.18.5/libexec/src/testing/testing.go:1392 +0x5d2
panic({0x17a37e0, 0xc0000b4180})
	/usr/local/Cellar/go/1.18.5/libexec/src/runtime/panic.go:844 +0x258
flag.(*FlagSet).Var(0xc00020c120, {0x19668c0, 0x1d00f90}, {0x186cfd4, 0x7}, {0x188d879, 0x52})
	/usr/local/Cellar/go/1.18.5/libexec/src/flag/flag.go:879 +0x3a5
flag.(*FlagSet).StringVar(...)
	/usr/local/Cellar/go/1.18.5/libexec/src/flag/flag.go:762
k8s.io/klog/v2.InitFlags(0x0)
	/Users/avoltz/src/blob-csi-driver/vendor/k8s.io/klog/v2/klog.go:424 +0xee
sigs.k8s.io/blob-csi-driver/pkg/csi-common.TestLogGRPC(0xc0000829c0)
	/Users/avoltz/src/blob-csi-driver/pkg/csi-common/utils_test.go:87 +0x45
testing.tRunner(0xc0000829c0, 0x18ae070)
	/usr/local/Cellar/go/1.18.5/libexec/src/testing/testing.go:1439 +0x214
created by testing.(*T).Run
	/usr/local/Cellar/go/1.18.5/libexec/src/testing/testing.go:1486 +0x725
FAIL	sigs.k8s.io/blob-csi-driver/pkg/csi-common	4.298s
FAIL

Author: anvoltz-msft

pkg/csi-common/utils_test.go

@@ -20,6 +20,8 @@ import (
 	"bytes"
 	"context"
 	"flag"
+	"io"
+	"os"
 	"testing"
 
 	"github.com/container-storage-interface/spec/lib/go/csi"
@@ -83,21 +85,9 @@ func TestParseEndpoint(t *testing.T) {
 }
 
 func TestLogGRPC(t *testing.T) {
-	// SET UP
-	klog.InitFlags(nil)
-	if e := flag.Set("logtostderr", "false"); e != nil {
-		t.Error(e)
-	}
-	if e := flag.Set("alsologtostderr", "false"); e != nil {
-		t.Error(e)
-	}
-	if e := flag.Set("v", "100"); e != nil {
-		t.Error(e)
-	}
-	flag.Parse()
-
 	buf := new(bytes.Buffer)
 	klog.SetOutput(buf)
+	defer klog.SetOutput(io.Discard)
 
 	handler := func(ctx context.Context, req interface{}) (interface{}, error) { return nil, nil }
 	info := grpc.UnaryServerInfo{
@@ -232,3 +222,12 @@ func TestGetLogLevel(t *testing.T) {
 		}
 	}
 }
+
+func TestMain(m *testing.M) {
+	klog.InitFlags(nil)
+	_ = flag.Set("logtostderr", "false")
+	_ = flag.Set("alsologtostderr", "false")
+	_ = flag.Set("v", "100")
+	klog.SetOutput(io.Discard)
+	os.Exit(m.Run())
+}