ipn/ipnlocal: make tests pass when offline

Updates #cleanup

Signed-off-by: Maisem Ali <maisem@tailscale.com>

ipn/ipnlocal/local.go

@@ -8,6 +8,7 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"errors"
+	"flag"
 	"fmt"
 	"io"
 	"log"
@@ -64,6 +65,7 @@ import (
 	"tailscale.com/types/dnstype"
 	"tailscale.com/types/empty"
 	"tailscale.com/types/key"
+	"tailscale.com/types/lazy"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/logid"
 	"tailscale.com/types/netmap"
@@ -91,6 +93,14 @@ import (
 	"tailscale.com/wgengine/wgcfg/nmcfg"
 )
 
+var lazyInTest lazy.SyncValue[bool]
+
+func inTest() bool {
+	return lazyInTest.Get(func() bool {
+		return flag.Lookup("test.v") != nil
+	})
+}
+
 var controlDebugFlags = getControlDebugFlags()
 
 func getControlDebugFlags() []string {
@@ -496,7 +506,7 @@ func (b *LocalBackend) maybePauseControlClientLocked() {
 		return
 	}
 	networkUp := b.prevIfState.AnyInterfaceUp()
-	b.cc.SetPaused((b.state == ipn.Stopped && b.netMap != nil) || !networkUp)
+	b.cc.SetPaused((b.state == ipn.Stopped && b.netMap != nil) || (!networkUp && !inTest()))
 }
 
 // linkChange is our network monitor callback, called whenever the network changes.