Fixes issue #70

game/src/main/org/apollo/game/model/Position.java

@@ -14,7 +14,7 @@ import com.google.common.base.Preconditions;
 public final class Position {
 
 	/**
-	 * The number of height levels.
+	 * The number of height levels, (0, 3] inclusive.
 	 */
 	public static final int HEIGHT_LEVELS = 4;
 
@@ -46,7 +46,7 @@ public final class Position {
 	 * @param height The height.
 	 */
 	public Position(int x, int y, int height) {
-		Preconditions.checkArgument(height >= 0 && height < HEIGHT_LEVELS, "Height level out of bounds.");
+		Preconditions.checkElementIndex(height, HEIGHT_LEVELS, "Height must be [0, 3), received " + height + ".");
 
 		packed = height << 30 | (y & 0x7FFF) << 15 | x & 0x7FFF;
 	}

game/src/test/org/apollo/game/model/TestPosition.java

@@ -0,0 +1,38 @@
+package org.apollo.game.model;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Tests the {@link Position} class.
+ * 
+ * @author Ryley
+ */
+public final class TestPosition {
+
+    /**
+     * Tests the {@link Position#getHeight()} method.
+     */
+    @Test
+    public void testGetHeight() {
+	Position position = new Position(3222, 3222, 3);
+	Assert.assertEquals(3, position.getHeight());
+    }
+
+    /**
+     * Tests the creation of an invalid {@link Position}.
+     */
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void testCreateNegativePosition() {
+	new Position(3222, 3222, -1);
+    }
+
+    /**
+     * Tests the creation of an invalid {@link Position}.
+     */
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void testCreateOutOfBoundsPosition() {
+	new Position(3222, 3222, 4);
+    }
+
+}