Method TestPickFirst_AddressesRemoved

balancer/pickfirst/pickfirst_ext_test.go:249–288

TestPickFirst_AddressesRemoved tests the scenario where we have multiple backends and pick_first is working as expected. It then verifies that when addresses are removed by the name resolver, RPCs get routed appropriately.

(t *testing.T)

// backends and pick_first is working as expected. It then verifies that when
// addresses are removed by the name resolver, RPCs get routed appropriately.
func (s) TestPickFirst_AddressesRemoved(t *testing.T) {
	cc, r, backends := setupPickFirst(t, 3)

	addrs := stubBackendsToResolverAddrs(backends)
	r.UpdateState(resolver.State{Addresses: addrs})

	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	if err := pickfirst.CheckRPCsToBackend(ctx, cc, addrs[0]); err != nil {
		t.Fatal(err)
	}

	// Remove the first backend from the list of addresses originally pushed.
	// RPCs should get routed to the first backend in the new list.
	r.UpdateState(resolver.State{Addresses: []resolver.Address{addrs[1], addrs[2]}})
	if err := pickfirst.CheckRPCsToBackend(ctx, cc, addrs[1]); err != nil {
		t.Fatal(err)
	}

	// Append the backend that we just removed to the end of the list.
	// Nothing should change.
	r.UpdateState(resolver.State{Addresses: []resolver.Address{addrs[1], addrs[2], addrs[0]}})
	if err := pickfirst.CheckRPCsToBackend(ctx, cc, addrs[1]); err != nil {
		t.Fatal(err)
	}

	// Remove the first backend from the existing list of addresses.
	// RPCs should get routed to the first backend in the new list.
	r.UpdateState(resolver.State{Addresses: []resolver.Address{addrs[2], addrs[0]}})
	if err := pickfirst.CheckRPCsToBackend(ctx, cc, addrs[2]); err != nil {
		t.Fatal(err)
	}

	// Remove the first backend from the existing list of addresses.
	// RPCs should get routed to the first backend in the new list.
	r.UpdateState(resolver.State{Addresses: []resolver.Address{addrs[0]}})
	if err := pickfirst.CheckRPCsToBackend(ctx, cc, addrs[0]); err != nil {
		t.Fatal(err)
	}
}

// TestPickFirst_NewAddressWhileBlocking tests the case where pick_first is
// configured on a channel, things are working as expected and then a resolver