Add get_purchase() function

src/ConvertKit_API.php

@@ -594,6 +594,8 @@ public function get_subscriber_tags(int $subscriber_id)
      *
      * @param array<string, string> $options Request options.
      *
+     * @see https://developers.convertkit.com/#list-purchases
+     *
      * @throws \InvalidArgumentException If the provided arguments are not of the expected type.
      *
      * @return false|object
@@ -610,11 +612,32 @@ public function list_purchases(array $options)
         return $this->get('purchases', $options);
     }
 
+    /**
+     * Retuns a specific purchase.
+     *
+     * @param integer $purchase_id Purchase ID.
+     *
+     * @see https://developers.convertkit.com/#retrieve-a-specific-purchase
+     *
+     * @return false|object
+     */
+    public function get_purchase(int $purchase_id)
+    {
+        return $this->get(
+            sprintf('purchases/%s', $purchase_id),
+            [
+                'api_secret' => $this->api_secret,
+            ]
+        );
+    }
+
     /**
      * Creates a purchase.
      *
      * @param array<string, string> $options Purchase data.
      *
+     * @see https://developers.convertkit.com/#create-a-purchase
+     *
      * @throws \InvalidArgumentException If the provided arguments are not of the expected type.
      *
      * @return false|object

tests/ConvertKitAPITest.php

@@ -712,6 +712,41 @@ public function testListPurchases()
         $this->assertArrayHasKey('purchases', get_object_vars($purchases));
     }
 
+    /**
+     * Test that get_purchases() returns the expected data.
+     *
+     * @since   1.0.0
+     *
+     * @return void
+     */
+    public function testGetPurchase()
+    {
+        // Get ID of first purchase.
+        $purchases = $this->api->list_purchases([
+            'page' => 1,
+        ]);
+        $id = $purchases->purchases[0]->id;
+
+        // Get purchase.
+        $result = $this->api->get_purchase($id);
+        $this->assertInstanceOf('stdClass', $result);
+        $this->assertEquals($result->id, $id);
+    }
+
+    /**
+     * Test that get_purchases() throws a ClientException when an invalid
+     * purchase ID is specified.
+     *
+     * @since   1.0.0
+     *
+     * @return void
+     */
+    public function testGetPurchaseWithInvalidID()
+    {
+        $this->expectException(GuzzleHttp\Exception\ClientException::class);
+        $this->api->get_purchase(12345);
+    }
+
     /**
      * Test that create_purchase() returns the expected data.
      *
@@ -758,6 +793,24 @@ public function testCreatePurchase()
         $this->assertArrayHasKey('transaction_id', get_object_vars($purchase));
     }
 
+    /**
+     * Test that create_purchase() throws a ClientException when an invalid
+     * purchase data is specified.
+     *
+     * @since   1.0.0
+     *
+     * @return void
+     */
+    public function testCreatePurchaseWithMissingData()
+    {
+        $this->expectException(GuzzleHttp\Exception\ClientException::class);
+        $this->api->create_purchase([
+            'invalid-key' => [
+                'transaction_id' => str_shuffle('wfervdrtgsdewrafvwefds'),
+            ],
+        ]);
+    }
+
     /**
      * Test that fetching a legacy form's markup works.
      *