[3625] Rename tests for Subnet4 selection from getSubnet to selectSubnet.

This is to unify the naming with the Subnet6 tests as well as with the
name of the function under test.

src/lib/dhcpsrv/tests/cfg_subnets4_unittest.cc

@@ -30,7 +30,7 @@ namespace {
 
 // This test verifies that it is possible to retrieve a subnet using an
 // IP address.
-TEST(CfgSubnets4Test, getSubnetByCiaddr) {
+TEST(CfgSubnets4Test, selectSubnetByCiaddr) {
     CfgSubnets4 cfg;
 
     // Create 3 subnets.
@@ -71,7 +71,7 @@ TEST(CfgSubnets4Test, getSubnetByCiaddr) {
 
 // This test verifies that when the classification information is specified for
 // subnets, the proper subnets are returned by the subnet configuration.
-TEST(CfgSubnets4Test, getSubnetByClasses) {
+TEST(CfgSubnets4Test, selectSubnetByClasses) {
     CfgSubnets4 cfg;
 
     // Create 3 subnets.
@@ -145,7 +145,7 @@ TEST(CfgSubnets4Test, getSubnetByClasses) {
 
 // This test verifies that the relay information can be used to retrieve the
 // subnet.
-TEST(CfgSubnetsTest, getSubnetByRelayAddress) {
+TEST(CfgSubnetsTest, selectSubnetByRelayAddress) {
     CfgSubnets4 cfg;
 
     // Create 3 subnets.
@@ -184,7 +184,7 @@ TEST(CfgSubnetsTest, getSubnetByRelayAddress) {
 
 // This test verifies that the subnet can be selected for the client
 // using a source address if the client hasn't set the ciaddr.
-TEST(CfgSubnetsTest, getSubnetNoCiaddr) {
+TEST(CfgSubnetsTest, selectSubnetNoCiaddr) {
     CfgSubnets4 cfg;
 
     // Create 3 subnets.
@@ -224,7 +224,7 @@ TEST(CfgSubnetsTest, getSubnetNoCiaddr) {
 
 // This test verifies that the subnet can be selected using an address
 // set on the local interface.
-TEST(CfgSubnetsTest, getSubnetInterface) {
+TEST(CfgSubnetsTest, selectSubnetInterface) {
     // The IfaceMgrTestConfig object initializes fake interfaces:
     // eth0, eth1 and lo on the configuration manager. The CfgSubnets4
     // object uses addresses assigned to these fake interfaces to