@@ -367,17 +367,29 @@ func TestDERPEndToEnd(t *testing.T) {
367367return true
368368},testutil .WaitLong ,testutil .IntervalMedium )
369369
370- // Swap out the DERPMapper for a fake one that only returns the proxy. This
371- // allows us to force the agent to pick the proxy as its preferred region.
372- oldDERPMapper := * api .AGPL .DERPMapper .Load ()
373- newDERPMapper := func (derpMap * tailcfg.DERPMap )* tailcfg.DERPMap {
374- derpMap = oldDERPMapper (derpMap )
375- // Strip everything but the proxy, which is region ID 10001.
376- derpMap .Regions = map [int ]* tailcfg.DERPRegion {
377- 10001 :derpMap .Regions [10001 ],
370+ // Wait until the proxy appears in the DERP map, and then swap out the DERP
371+ // map for one that only contains the proxy region. This allows us to force
372+ // the agent to pick the proxy as its preferred region.
373+ var proxyOnlyDERPMap * tailcfg.DERPMap
374+ require .Eventually (t ,func ()bool {
375+ derpMap := api .AGPL .DERPMap ()
376+ if derpMap == nil {
377+ return false
378+ }
379+ if _ ,ok := derpMap .Regions [10001 ];! ok {
380+ return false
378381}
379- derpMap .OmitDefaultRegions = true
380- return derpMap
382+
383+ // Make a DERP map that only contains the proxy region.
384+ proxyOnlyDERPMap = derpMap .Clone ()
385+ proxyOnlyDERPMap .Regions = map [int ]* tailcfg.DERPRegion {
386+ 10001 :proxyOnlyDERPMap .Regions [10001 ],
387+ }
388+ proxyOnlyDERPMap .OmitDefaultRegions = true
389+ return true
390+ },testutil .WaitLong ,testutil .IntervalMedium )
391+ newDERPMapper := func (derpMap * tailcfg.DERPMap )* tailcfg.DERPMap {
392+ return proxyOnlyDERPMap
381393}
382394api .AGPL .DERPMapper .Store (& newDERPMapper )
383395