diff --git a/tests/Support/Fixtures/site-trees/default.php b/tests/Support/Fixtures/site-trees/default.php
new file mode 100644
index 00000000..62662877
--- /dev/null
+++ b/tests/Support/Fixtures/site-trees/default.php
@@ -0,0 +1,48 @@
+<?php
+
+/**
+ * Default site tree. If added to a new site, has the structure:
+ * /
+ * /undergraduates
+ * /undergraduates/2017
+ * /undergraduates/2018
+ * /postgraduates
+ * /postgraduates/2017
+ * /postgraduates/2018
+ */
+return [
+	[
+		'slug' => 'undergraduate',
+		'title' => 'Undergraduates',
+		'layout' => ['name' => 'test-layout', 'version' => 1],
+		'children' => [
+			[
+				'slug' => '2017',
+				'title' => '2017 Entry',
+				'layout' => ['name' => 'test-layout', 'version' => 1]
+			],
+			[
+				'slug' => '2018',
+				'title' => '2018 Entry',
+				'layout' => ['name' => 'test-layout', 'version' => 1]
+			],
+		]
+	],
+	[
+		'slug' => 'postgraduate',
+		'title' => 'Postgraduates',
+		'layout' => ['name' => 'test-layout', 'version' => 1],
+		'children' => [
+			[
+				'slug' => '2017',
+				'title' => '2017 Entry',
+				'layout' => ['name' => 'test-layout', 'version' => 1]
+			],
+			[
+				'slug' => '2018',
+				'title' => '2018 Entry',
+				'layout' => ['name' => 'test-layout', 'version' => 1]
+			],
+		]
+	]
+];
diff --git a/tests/Unit/Models/APICommands/APICommandTestCase.php b/tests/Unit/Models/APICommands/APICommandTestCase.php
index b4f616d7..6b0e58ea 100644
--- a/tests/Unit/Models/APICommands/APICommandTestCase.php
+++ b/tests/Unit/Models/APICommands/APICommandTestCase.php
@@ -4,15 +4,25 @@
 
 use App\Models\Contracts\APICommand;
 use App\Models\LocalAPIClient;
+use App\Models\PublishingGroup;
 use Exception;
 use Illuminate\Contracts\Auth\Authenticatable;
+use Illuminate\Foundation\Testing\DatabaseTransactions;
 use Illuminate\Support\Facades\Config;
 use Tests\TestCase;
 use Illuminate\Support\Facades\Validator;
 use App\Models\User;
 
+/**
+ * Utility methods for testing the API Commands.
+ * Includes methods for setting up test fixtures.
+ * @package Tests\Unit\Models\APICommands
+ */
 abstract class APICommandTestCase extends TestCase
 {
+	// wraps all database calls within a test in a transaction.
+	use DatabaseTransactions;
+
     /**
      * @var array A valid (existing) layout name and version
      */
@@ -22,15 +32,49 @@ abstract class APICommandTestCase extends TestCase
     ];
 
     /**
+	 * Should be implemented to return an array of input data which would be valid for the command
+	 * being tested.
+	 * Used by @see APICommandTestCase::input() to get some valid default data to use in a test.
      * @return array Valid input data.
      */
     abstract public function getValidData();
 
     /**
+	 * Should return an instance of the command class under test.
      * @return APICommand A new instance of the class to test.
      */
     abstract public function fixture();
 
+	/**
+	 * Create a site with an initial draft page hierarchy to use for testing.
+	 * @param LocalAPIClient $api Used to create the site, etc.
+	 * @param $structure
+	 * @param string $name - The name for the site to add.
+	 * @return Site - The created Site.
+	 */
+    public function setupSite(LocalAPIClient $api, $structure, $name)
+	{
+		$pubgroup = PublishingGroup::create(['name' => 'test']);
+		try{
+			$site = $api->createSite($pubgroup->id, "Test", "dfgkent.ac.uk", "", [ "name" => "test-layout", "version" => 1]);
+		}catch(\Exception $e){
+			dd($e);
+		}
+		$api->addTree($site->homepage->id, null, $structure);
+		return $site;
+	}
+
+	/**
+	 * Loads a site structure definition to use with $api->addTree from a php file.
+	 * Assumes that the file returns an array.
+	 * @param string $name - The name of the file without the .php extension.
+	 * @return array - An array defining the site hierarchy.
+	 */
+	public function loadSiteStructure($name)
+	{
+		return require(dirname(__FILE__) . '/../../../Support/Fixtures/site-trees/' . $name . '.php');
+	}
+
     /**
      * Get an API Client to use.
      * @param Authenticatable|null $user Optional Authenticatable. If null, will be auto-provided.
diff --git a/tests/Unit/Models/APICommands/AddPageTest.php b/tests/Unit/Models/APICommands/AddPageTest.php
index 2f45341a..a2b9afad 100644
--- a/tests/Unit/Models/APICommands/AddPageTest.php
+++ b/tests/Unit/Models/APICommands/AddPageTest.php
@@ -88,7 +88,11 @@ public function validation_whenParentID_IsMissing()
      */
     public function validation_whenParent_existsButIsNotDraft_fails()
     {
-        $this->markTestIncomplete();
+    	$api = $this->api();
+        $site = $this->setupSite($api, $this->loadSiteStructure('default'), 'Test');
+        $api->publishPage($site->homepage->id);
+        $api->publishPage($site->homepage->children()->first()->id);
+
     }
 
     /**