diff --git a/tests/feature/FieldGettersTest.php b/tests/feature/FieldGettersTest.php
index bd1b550..ad86dfd 100644
--- a/tests/feature/FieldGettersTest.php
+++ b/tests/feature/FieldGettersTest.php
@@ -11,24 +11,150 @@
 
 namespace Tobyz\Tests\JsonApiServer\feature;
 
+use Tobyz\JsonApiServer\Context;
+use Tobyz\JsonApiServer\JsonApi;
+use Tobyz\JsonApiServer\Schema\Type;
 use Tobyz\Tests\JsonApiServer\AbstractTestCase;
+use Tobyz\Tests\JsonApiServer\MockAdapter;
 
 class FieldGettersTest extends AbstractTestCase
 {
+    /**
+     * @var JsonApi
+     */
+    private $api;
+
+    /**
+     * @var MockAdapter
+     */
+    private $adapter;
+
     public function setUp(): void
     {
+        $this->api = new JsonApi('/');
 
+        $this->adapter = new MockAdapter([
+            '1' => (object) [
+                'id' => '1',
+                'test' => 'value',
+                'animal' => (object) ['id' => '1'],
+                'animals' => [
+                    (object) ['id' => '1'],
+                    (object) ['id' => '2']
+                ]
+            ]
+        ]);
     }
 
     public function test_attribute_values_are_retrieved_via_the_adapter_by_default()
     {
-        $this->markTestIncomplete();
+        $this->api->resource('users', $this->adapter, function (Type $type) {
+            $type->attribute('test');
+        });
+
+        $response = $this->api->handle(
+            $this->buildRequest('GET', '/users/1')
+        );
+
+        $document = json_decode($response->getBody());
+
+        $this->assertEquals('value', $document->data->attributes->test ?? null);
     }
 
     public function test_attribute_getters_allow_a_custom_value_to_be_used()
     {
-        $this->markTestIncomplete();
+        $this->api->resource('users', $this->adapter, function (Type $type) {
+            $type->attribute('test')
+                ->get(function ($model, Context $context) {
+                    return 'custom';
+                });
+        });
+
+        $response = $this->api->handle(
+            $this->buildRequest('GET', '/users/1')
+        );
+
+        $document = json_decode($response->getBody());
+
+        $this->assertEquals('custom', $document->data->attributes->test ?? null);
     }
 
-    // to_one, to_many...
+    public function test_has_one_values_are_retrieved_via_the_adapter_by_default()
+    {
+        $this->api->resource('users', $this->adapter, function (Type $type) {
+            $type->hasOne('animal')->withLinkage();
+        });
+
+        $this->api->resource('animals', new MockAdapter);
+
+        $response = $this->api->handle(
+            $this->buildRequest('GET', '/users/1')
+        );
+
+        $document = json_decode($response->getBody());
+
+        $this->assertEquals('1', $document->data->relationships->animal->data->id ?? null);
+    }
+
+    public function test_has_one_getters_allow_a_custom_value_to_be_used()
+    {
+        $this->api->resource('users', $this->adapter, function (Type $type) {
+            $type->hasOne('animal')->withLinkage()
+                ->get(function ($model, Context $context) {
+                    return (object) ['id' => '2'];
+                });
+        });
+
+        $this->api->resource('animals', new MockAdapter);
+
+        $response = $this->api->handle(
+            $this->buildRequest('GET', '/users/1')
+        );
+
+        $document = json_decode($response->getBody());
+
+        $this->assertEquals('2', $document->data->relationships->animal->data->id ?? null);
+    }
+
+    public function test_has_many_values_are_retrieved_via_the_adapter_by_default()
+    {
+        $this->api->resource('users', $this->adapter, function (Type $type) {
+            $type->hasMany('animals')->withLinkage();
+        });
+
+        $this->api->resource('animals', new MockAdapter);
+
+        $response = $this->api->handle(
+            $this->buildRequest('GET', '/users/1')
+        );
+
+        $document = json_decode($response->getBody());
+
+        $this->assertEquals('1', $document->data->relationships->animals->data[0]->id ?? null);
+        $this->assertEquals('2', $document->data->relationships->animals->data[1]->id ?? null);
+    }
+
+    public function test_has_many_getters_allow_a_custom_value_to_be_used()
+    {
+        $this->api->resource('users', $this->adapter, function (Type $type) {
+            $type->hasMany('animals')->withLinkage()
+                ->get(function ($model, Context $context) {
+                    return [
+                        (object) ['id' => '2'],
+                        (object) ['id' => '3']
+                    ];
+                });
+        });
+
+        $this->api->resource('animals', new MockAdapter);
+
+        $response = $this->api->handle(
+            $this->buildRequest('GET', '/users/1')
+        );
+
+        $document = json_decode($response->getBody());
+
+        $this->assertEquals('2', $document->data->relationships->animals->data[0]->id ?? null);
+        $this->assertEquals('3', $document->data->relationships->animals->data[1]->id ?? null);
+    }
 }