Add test for LoginCommand; create AuthMe mock test util

Had to create a getter for the Management instance in the AuthMe class for mocking, but fields should generally not be accessed globally. Hopefully soon we will be able to make the field private.
(cherry picked from commit f1a0022)

src/main/java/fr/xephi/authme/AuthMe.java

@@ -1028,4 +1028,9 @@ public class AuthMe extends JavaPlugin {
     public static int getVersionCode() {
         return PLUGIN_VERSION_CODE;
     }
+
+    /** Returns the management instance. */
+    public Management getManagement() {
+        return management;
+    }
 }

src/main/java/fr/xephi/authme/command/executable/login/LoginCommand.java

@@ -24,7 +24,7 @@ public class LoginCommand extends ExecutableCommand {
         final String playerPass = commandArguments.get(0);
 
         // Log the player in
-        plugin.management.performLogin(player, playerPass, false);
+        plugin.getManagement().performLogin(player, playerPass, false);
         return true;
     }
 }

src/test/java/fr/xephi/authme/AuthMeMockUtil.java

@@ -0,0 +1,30 @@
+package fr.xephi.authme;
+
+import org.mockito.Mockito;
+
+import java.lang.reflect.Field;
+
+/**
+ * Creates a mock implementation of AuthMe for testing purposes.
+ */
+public final class AuthMeMockUtil {
+
+    private AuthMeMockUtil() {
+        // Util class
+    }
+
+    /**
+     * Set the AuthMe plugin instance to a mock object. Use {@link AuthMe#getInstance()} to retrieve the mock.
+     */
+    public static void initialize() {
+        AuthMe mock = Mockito.mock(AuthMe.class);
+
+        try {
+            Field instance = AuthMe.class.getDeclaredField("plugin");
+            instance.setAccessible(true);
+            instance.set(null, mock);
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            throw new RuntimeException("Could not initialize AuthMe mock", e);
+        }
+    }
+}

src/test/java/fr/xephi/authme/command/executable/login/LoginCommandTest.java

@@ -0,0 +1,77 @@
+package fr.xephi.authme.command.executable.login;
+
+import fr.xephi.authme.AuthMe;
+import fr.xephi.authme.AuthMeMockUtil;
+import fr.xephi.authme.command.CommandParts;
+import fr.xephi.authme.process.Management;
+import fr.xephi.authme.settings.Settings;
+import org.bukkit.command.BlockCommandSender;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mockito;
+
+
+import static org.mockito.Matchers.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+
+/**
+ * Test for {@link LoginCommand}.
+ */
+public class LoginCommandTest {
+
+    private static Management managementMock;
+
+    @Before
+    public void initializeAuthMeMock() {
+        AuthMeMockUtil.initialize();
+        AuthMe pluginMock = AuthMe.getInstance();
+
+        Settings.captchaLength = 10;
+        managementMock = mock(Management.class);
+        Mockito.when(pluginMock.getManagement()).thenReturn(managementMock);
+    }
+
+    @Test
+    public void shouldStopIfSenderIsNotAPlayer() {
+        // given
+        CommandSender sender = mock(BlockCommandSender.class);
+        LoginCommand command = new LoginCommand();
+
+        // when
+        command.executeCommand(sender, new CommandParts(), new CommandParts());
+
+        // then
+        Mockito.verify(managementMock, never()).performLogin(any(Player.class), anyString(), anyBoolean());
+    }
+
+    @Test
+    public void shouldCallManagementForPlayerCaller() {
+        // given
+        Player sender = mock(Player.class);
+        LoginCommand command = new LoginCommand();
+
+        // when
+        command.executeCommand(sender, new CommandParts(), new CommandParts("password"));
+
+        // then
+        Mockito.verify(managementMock).performLogin(eq(sender), eq("password"), eq(false));
+    }
+
+    @Test
+    public void shouldHandleMissingPassword() {
+        // given
+        Player sender = mock(Player.class);
+        LoginCommand command = new LoginCommand();
+
+        // when
+        command.executeCommand(sender, new CommandParts(), new CommandParts());
+
+        // then
+        // TODO ljacqu 20151121: May make sense to handle null password in LoginCommand instead of forwarding the call
+        String password = null;
+        Mockito.verify(managementMock).performLogin(eq(sender), eq(password), eq(false));
+    }
+}