diff --git a/classes/ComicPressDBInterface.inc b/classes/ComicPressDBInterface.inc
index 1e52c64..0e42de9 100644
--- a/classes/ComicPressDBInterface.inc
+++ b/classes/ComicPressDBInterface.inc
@@ -18,12 +18,7 @@ class ComicPressDBInterface {
    * Set the comic categories for the current run of ComicPress.
    */
   function set_comic_categories($categories) {
-    $this->_non_comic_categories = array();
-    $this->_all_categories       = array();
-    foreach ($this->_get_categories() as $category_object) {
-      $this->_all_categories[] = $category_object->term_id;
-    }
-
+    $this->_all_categories       = get_all_category_ids();
     $this->_non_comic_categories = array_values(array_diff($this->_all_categories, $categories));
   }
 
@@ -60,10 +55,11 @@ class ComicPressDBInterface {
 
   /**
    * Get the comic post adjacent to the current comic.
+   * Wrapper around get_adjacent_post(). Don't unit test this method.
    */
   function get_adjacent_comic($category, $next = false, $override_post = null) {
     global $wp_query, $post;
-    $temp = $wp_query->is_single;
+    $temp_single = $wp_query->is_single;
     $wp_query->is_single = true;
     
     if (!is_null($override_post)) {
@@ -71,9 +67,9 @@ class ComicPressDBInterface {
       $post = $override_post; 
     }
     
-    $result = get_adjacent_post(false, implode(" and ", $categories_to_exclude), !$next);
+    $result = get_adjacent_post(false, implode(" and ", $this->_get_categories_to_exclude($category)), !$next);
 
-    $wp_query->is_single = $temp;
+    $wp_query->is_single = $temp_single;
     
     if (!is_null($override_post)) {
       $post = $temp_post; 
diff --git a/classes/ComicPressNavigation.inc b/classes/ComicPressNavigation.inc
index 9f14b39..600a343 100644
--- a/classes/ComicPressNavigation.inc
+++ b/classes/ComicPressNavigation.inc
@@ -1,7 +1,22 @@
 <?php
 
-class ComicPressNavigation {
+require_once('ComicPressStoryline.inc');
+require_once('ComicPressDBInterface.inc');
 
+class ComicPressNavigation {
+  function init($storyline) {
+    $this->_storyline = $storyline;
+    $this->_dbi       = ComicPressDBInterface::get_instance();
+  }
+
+  function get_post_nav($post) {
+    $nav = array();
+
+    // post
+    foreach (array('previous', 'next') as $field) {
+      $nav[$field] = $this->_dbi->{"get_${field}_comic"}(null, $post);
+    }
+  }
 }
 
 ?>
\ No newline at end of file
diff --git a/test/ComicPressDBInterfaceTest.php b/test/ComicPressDBInterfaceTest.php
index d63f137..e6dd5b2 100644
--- a/test/ComicPressDBInterfaceTest.php
+++ b/test/ComicPressDBInterfaceTest.php
@@ -16,14 +16,9 @@ class ComicPressDBInterfaceTest extends PHPUnit_Framework_TestCase {
   }
 
   function testSetComicCategories() {
-    $dbi = $this->getMock('ComicPressDBInterface', array('_get_categories'));
-
-    $dbi->expects($this->once())->method('_get_categories')->will($this->returnValue(array(
-      (object)array('term_id' => 1),
-      (object)array('term_id' => 2),
-      (object)array('term_id' => 3),
-      (object)array('term_id' => 4)
-    )));
+    $dbi = ComicPressDBInterface::get_instance();
+  
+    for ($i = 1; $i <= 4; ++$i) { add_category($i, (object)array()); }
 
     $dbi->set_comic_categories(array(2,3));
 
diff --git a/test/ComicPressNavigationTest.php b/test/ComicPressNavigationTest.php
index 50e6996..4b217ca 100644
--- a/test/ComicPressNavigationTest.php
+++ b/test/ComicPressNavigationTest.php
@@ -4,14 +4,29 @@ require_once('MockPress/mockpress.php');
 require_once('PHPUnit/Framework.php');
 require_once(dirname(__FILE__) . '/../classes/ComicPressNavigation.inc');
 
+/**
+ * Integration Testing. Just make sure things are called correctly.
+ */
 class ComicPressNavigationTest extends PHPUnit_Framework_TestCase {
   function setUp() {
     _reset_wp();
     $this->nav = new ComicPressNavigation();
   }
   
-  function testSomething() {
-    $this->markTestIncomplete();
+  function testGetPostNav() {
+    $dbi = $this->getMock('ComicPressDBInterface', array('get_previous_comic', 'get_next_comic'));
+
+    wp_insert_post(array('ID' => 1));
+    $post = get_post(1);
+
+    wp_set_post_categories(1, array(1));
+
+    $dbi->expects($this->once())->method('get_previous_comic')->with(null, $post);
+    $dbi->expects($this->once())->method('get_next_comic')->with(null, $post);
+
+    $this->nav->_dbi = $dbi;
+
+    $this->nav->get_post_nav($post);
   }
 }