Add some tests, minor Checkstyle fixes

src/test/java/fr/xephi/authme/util/FileUtilsTest.java

@@ -75,6 +75,20 @@ public class FileUtilsTest {
         assertThat(file.exists(), equalTo(false));
     }
 
+    @Test
+    public void shouldReturnFalseForParentInvalidParentFolders() throws IOException {
+        // given
+        File folder = temporaryFolder.newFolder();
+        new File(folder, "hello").createNewFile();
+        File fileToCreate = new File(folder, "hello/test");
+
+        // when
+        boolean result = FileUtils.copyFileFromResource(fileToCreate, "welcome.txt");
+
+        // then
+        assertThat(result, equalTo(false));
+    }
+
     @Test
     public void shouldPurgeDirectory() throws IOException {
         // given
@@ -137,6 +151,36 @@ public class FileUtilsTest {
         assertThat(result, equalTo("path" + File.separator + "to" + File.separator + "test-file.txt"));
     }
 
+    @Test
+    public void shouldCreateDirectory() throws IOException {
+        // given
+        File root = temporaryFolder.newFolder();
+        File dir = new File(root, "folder/folder2/myFolder");
+
+        // when
+        boolean result = FileUtils.createDirectory(dir);
+
+        // then
+        assertThat(result, equalTo(true));
+        assertThat(dir.exists(), equalTo(true));
+        assertThat(dir.isDirectory(), equalTo(true));
+    }
+
+    @Test
+    public void shouldReturnFalseOnDirectoryCreateFail() throws IOException {
+        // given
+        File root = temporaryFolder.newFolder();
+        File dirAsFile = new File(root, "file");
+        dirAsFile.createNewFile();
+
+        // when
+        boolean result = FileUtils.createDirectory(dirAsFile);
+
+        // then
+        assertThat(result, equalTo(false));
+        assertThat(dirAsFile.isFile(), equalTo(true));
+    }
+
     @Test
     public void shouldHaveHiddenConstructor() {
         TestHelper.validateHasOnlyPrivateEmptyConstructor(FileUtils.class);

src/test/java/fr/xephi/authme/util/InternetProtocolUtilsTest.java

@@ -1,5 +1,6 @@
 package fr.xephi.authme.util;
 
+import fr.xephi.authme.TestHelper;
 import org.junit.Test;
 
 import static org.junit.Assert.assertThat;
@@ -19,4 +20,10 @@ public class InternetProtocolUtilsTest {
         assertThat(InternetProtocolUtils.isLocalAddress("192.168.0.1"), equalTo(true));
         assertThat(InternetProtocolUtils.isLocalAddress("94.32.34.5"), equalTo(false));
     }
+
+    @Test
+    public void shouldHavePrivateConstructor() {
+        // given / when / then
+        TestHelper.validateHasOnlyPrivateEmptyConstructor(InternetProtocolUtils.class);
+    }
 }

src/test/java/fr/xephi/authme/util/RandomStringUtilsTest.java

@@ -53,7 +53,7 @@ public class RandomStringUtilsTest {
 
         // when / then
         for (int length : lengths) {
-            String result = RandomStringUtils.generateHex(length);
+            String result = RandomStringUtils.generateLowerUpper(length);
             assertThat("Result '" + result + "' should have length " + length,
                 result.length(), equalTo(length));
             assertThat("Result '" + result + "' should only have characters a-z, A-Z, 0-9",

src/test/java/fr/xephi/authme/util/UtilsTest.java

@@ -1,16 +1,22 @@
 package fr.xephi.authme.util;
 
 import fr.xephi.authme.TestHelper;
+import org.bukkit.ChatColor;
 import org.bukkit.command.CommandSender;
 import org.bukkit.command.ConsoleCommandSender;
 import org.bukkit.entity.Player;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.greaterThan;
 import static org.junit.Assert.assertThat;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
@@ -99,6 +105,68 @@ public class UtilsTest {
         verifyZeroInteractions(sender);
     }
 
+    @Test
+    public void shouldCheckIfCollectionIsEmpty() {
+        // given
+        List<String> emptyList = Collections.emptyList();
+        Collection<Integer> nonEmptyColl = Arrays.asList(3, 4, 5);
+
+        // when / then
+        assertThat(Utils.isCollectionEmpty(emptyList), equalTo(true));
+        assertThat(Utils.isCollectionEmpty(nonEmptyColl), equalTo(false));
+        assertThat(Utils.isCollectionEmpty(null), equalTo(true));
+    }
+
+    @Test
+    public void shouldReturnCoreCount() {
+        // given / when / then
+        assertThat(Utils.getCoreCount(), greaterThan(0));
+    }
+
+    @Test
+    public void shouldLogAndSendWarning() {
+        // given
+        Logger logger = TestHelper.setupLogger();
+        String message = "Error while performing action";
+        CommandSender sender = mock(CommandSender.class);
+
+        // when
+        Utils.logAndSendWarning(sender, message);
+
+        // then
+        verify(logger).warning(message);
+        verify(sender).sendMessage(ChatColor.RED + message);
+    }
+
+    @Test
+    public void shouldLogWarningAndNotSendToConsoleSender() {
+        // given
+        Logger logger = TestHelper.setupLogger();
+        String message = "Error while performing action";
+        CommandSender sender = mock(ConsoleCommandSender.class);
+
+        // when
+        Utils.logAndSendWarning(sender, message);
+
+        // then
+        verify(logger).warning(message);
+        verifyZeroInteractions(sender);
+    }
+
+    @Test
+    public void shouldLogWarningAndHandleNullCommandSender() {
+        // given
+        Logger logger = TestHelper.setupLogger();
+        String message = "Error while performing action";
+        CommandSender sender = null;
+
+        // when
+        Utils.logAndSendWarning(sender, message);
+
+        // then
+        verify(logger).warning(message);
+    }
+
     @Test
     public void shouldCheckIfClassIsLoaded() {
         // given / when / then