You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: connectionmanager_test.go
    path of file: ./repos/chainlink/core/services/gateway
    
    the code of the file until where you have to start completion: package gateway_test

import (
	"crypto/ecdsa"
	"fmt"
	"testing"

	"github.com/jonboulle/clockwork"
	"github.com/stretchr/testify/require"

	"github.com/smartcontractkit/chainlink/v2/core/internal/testutils"
	"github.com/smartcontractkit/chainlink/v2/core/logger"
	"github.com/smartcontractkit/chainlink/v2/core/services/gateway"
	"github.com/smartcontractkit/chainlink/v2/core/services/gateway/api"
	gc "github.com/smartcontractkit/chainlink/v2/core/services/gateway/common"
	"github.com/smartcontractkit/chainlink/v2/core/services/gateway/config"
	"github.com/smartcontractkit/chainlink/v2/core/services/gateway/network"
)

const defaultConfig = `
[nodeServerConfig]
Path = "/node"

[[dons]]
DonId = "my_don_1"
HandlerName = "dummy"

[[dons.mem
    
func TestConnectionManager_NewConnectionManager_InvalidConfig(t *testing.T) {
	t.Parallel()

	invalidCases := map[string]string{
		"duplicate DON ID": `
[[dons]]
DonId = "my_don"
[[dons]]
DonId = "my_don"
`,
		"duplicate node address": `
[[dons]]
DonId = "my_don"
[[dons.members]]
Name = "node_1"
Address = "0x68902d681c28119f9b2531473a417088bf008e59"
[[dons.members]]
Name = "node_2"
Address = "0x68902d681c28119f9b2531473a417088bf008e59"
`,
		"duplicate node address with different casing": `
[[dons]]
DonId = "my_don"
[[dons.members]]
Name = "node_1"
Address = "0x68902d681c28119f9b2531473a417088bf008e59"
[[dons.members]]
Name = "node_2"
Address = "0x68902D681c28119f9b2531473a417088bf008E59"
`,
	}

	for name, config := range invalidCases {
		config := config
		t.Run(name, func(t *testing.T) {
			fullConfig := `
[nodeServerConfig]
Path = "/node"` + config
			_, err := gateway.NewConnectionManager(parseTOMLConfig(t, fullConfig), clockwork.NewFakeClock(), logger.TestLogger(t))
			require.Error(t, err)
		})
	}
}