fix 5868 -fix DefaultHostsFileEntriesResolverTest to pass on windows 7

Motivation:

Windows 7 hosts file is empty by default (at least on my machine? see
http://serverfault.com/questions/4689/windows-7-localhost-name-resolution-is-handled-within-dns-itself-why
for details and reasoning.

the test relies on the file containing an entry for localhost.

Modifications:

refactor class code to 1st normalize the input host name and then look it up, change the test to verify
that hostnames are normalized in a case-insensitive way before being looked up (which was the intent
of the original test)

Result:

test should pass on vanilla windows 7 (and any other machine with no
localhost in the hosts file). no effect anywhere else or on actual netty
code.

Signed-off-by: radai-rosenblatt <radai.rosenblatt@gmail.com>

resolver/src/main/java/io/netty/resolver/DefaultHostsFileEntriesResolver.java

@@ -28,6 +28,11 @@ public final class DefaultHostsFileEntriesResolver implements HostsFileEntriesRe
 
     @Override
     public InetAddress address(String inetHost) {
-        return entries.get(inetHost.toLowerCase(Locale.ENGLISH));
+        return entries.get(normalize(inetHost));
+    }
+
+    // package-private for testing purposes
+    String normalize(String inetHost) {
+        return inetHost.toLowerCase(Locale.ENGLISH);
     }
 }

resolver/src/test/java/io/netty/resolver/DefaultHostsFileEntriesResolverTest.java

@@ -19,16 +19,15 @@
  */
 package io.netty.resolver;
 
+import org.junit.Assert;
 import org.junit.Test;
 
-import static org.junit.Assert.assertNotNull;
-
 public class DefaultHostsFileEntriesResolverTest {
 
     @Test
-    public void testLocalhost() {
+    public void testCaseInsensitivity() throws Exception {
         DefaultHostsFileEntriesResolver resolver = new DefaultHostsFileEntriesResolver();
-        assertNotNull("localhost doesn't resolve", resolver.address("localhost"));
-        assertNotNull("LOCALHOST doesn't resolve", resolver.address("LOCALHOST"));
+        //normalized somehow
+        Assert.assertEquals(resolver.normalize("localhost"), resolver.normalize("LOCALHOST"));
     }
 }