consul: refactor GetPrivateIP for testability

consul/server_test.go

@@ -120,9 +120,10 @@ func TestServer_StartStop(t *testing.T) {
 	config := DefaultConfig()
 	config.DataDir = dir
 
-	private, err := GetPrivateIP()
+	// Advertise on localhost.
+	private, _, err := net.ParseCIDR("127.0.0.1/32")
 	if err != nil {
-		t.Fatalf("err: %v", err)
+		t.Fatalf("failed to parse 127.0.0.1 cidr: %v", err)
 	}
 
 	config.RPCAdvertise = &net.TCPAddr{

consul/util.go

@@ -169,6 +169,10 @@ func GetPrivateIP() (net.IP, error) {
 		return nil, fmt.Errorf("Failed to get interface addresses: %v", err)
 	}
 
+	return getPrivateIP(addresses)
+}
+
+func getPrivateIP(addresses []net.Addr) (net.IP, error) {
 	var candidates []net.IP
 
 	// Find private IPv4 address
@@ -200,6 +204,7 @@ func GetPrivateIP() (net.IP, error) {
 	default:
 		return nil, fmt.Errorf("Multiple private IPs found. Please configure one.")
 	}
+
 }
 
 // Converts bytes to an integer

consul/util_test.go

@@ -1,6 +1,7 @@
 package consul
 
 import (
+	"errors"
 	"net"
 	"regexp"
 	"testing"
@@ -28,6 +29,74 @@ func TestToLowerList(t *testing.T) {
 	}
 }
 
+func TestGetPrivateIP(t *testing.T) {
+	ip, _, err := net.ParseCIDR("10.1.2.3/32")
+	if err != nil {
+		t.Fatalf("failed to parse private cidr: %v", err)
+	}
+
+	pubIP, _, err := net.ParseCIDR("8.8.8.8/32")
+	if err != nil {
+		t.Fatalf("failed to parse public cidr: %v", err)
+	}
+
+	tests := []struct {
+		addrs    []net.Addr
+		expected net.IP
+		err      error
+	}{
+		{
+			addrs: []net.Addr{
+				&net.IPAddr{
+					IP: ip,
+				},
+				&net.IPAddr{
+					IP: pubIP,
+				},
+			},
+			expected: ip,
+		},
+		{
+			addrs: []net.Addr{
+				&net.IPAddr{
+					IP: pubIP,
+				},
+			},
+			err: errors.New("No private IP address found"),
+		},
+		{
+			addrs: []net.Addr{
+				&net.IPAddr{
+					IP: ip,
+				},
+				&net.IPAddr{
+					IP: ip,
+				},
+				&net.IPAddr{
+					IP: pubIP,
+				},
+			},
+			err: errors.New("Multiple private IPs found. Please configure one."),
+		},
+	}
+
+	for _, test := range tests {
+		ip, err := getPrivateIP(test.addrs)
+		switch {
+		case test.err != nil && err != nil:
+			if err.Error() != test.err.Error() {
+				t.Fatalf("unexpected error: %v != %v", test.err, err)
+			}
+		case (test.err == nil && err != nil) || (test.err != nil && err == nil):
+			t.Fatalf("unexpected error: %v != %v", test.err, err)
+		default:
+			if !test.expected.Equal(ip) {
+				t.Fatalf("unexpected ip: %v != %v", ip, test.expected)
+			}
+		}
+	}
+}
+
 func TestIsPrivateIP(t *testing.T) {
 	if !isPrivateIP("192.168.1.1") {
 		t.Fatalf("bad")