Method TestPickFirst_ParseConfig_Success

balancer/pickfirst/pickfirst_ext_test.go:633–691

Test config parsing with the env var turned on and off for various scenarios.

(t *testing.T)

// Test config parsing with the env var turned on and off for various scenarios.
func (s) TestPickFirst_ParseConfig_Success(t *testing.T) {
	testutils.SetEnvConfig(t, &envconfig.PickFirstWeightedShuffling, false)

	// Install a shuffler that always reverses two entries.
	origShuf := pfinternal.RandShuffle
	defer func() { pfinternal.RandShuffle = origShuf }()
	pfinternal.RandShuffle = func(n int, f func(int, int)) {
		if n != 2 {
			t.Errorf("Shuffle called with n=%v; want 2", n)
			return
		}
		f(0, 1) // reverse the two addresses
	}

	tests := []struct {
		name          string
		serviceConfig string
		wantFirstAddr bool
	}{
		{
			name:          "empty pickfirst config",
			serviceConfig: `{"loadBalancingConfig": [{"pick_first":{}}]}`,
			wantFirstAddr: true,
		},
		{
			name:          "empty good pickfirst config",
			serviceConfig: `{"loadBalancingConfig": [{"pick_first":{ "shuffleAddressList": true }}]}`,
			wantFirstAddr: false,
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			// Set up our backends.
			cc, r, backends := setupPickFirst(t, 2)
			addrs := stubBackendsToResolverAddrs(backends)

			r.UpdateState(resolver.State{
				ServiceConfig: parseServiceConfig(t, r, test.serviceConfig),
				Addresses:     addrs,
			})

			// Some tests expect address shuffling to happen, and indicate that
			// by setting wantFirstAddr to false (since our shuffling function
			// defined at the top of this test, simply reverses the list of
			// addresses provided to it).
			wantAddr := addrs[0]
			if !test.wantFirstAddr {
				wantAddr = addrs[1]
			}

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