Fix sort order tests

TESTING.md

@@ -36,6 +36,26 @@ If a test fails, you can inspect the output.
 
 Any errors should be corrected by making applicable code or test changes.
 
+## Run PHP CodeSniffer
+
+[PHP_CodeSniffer](https://github.com/squizlabs/PHP_CodeSniffer) checks that all code meets the [PSR-12 Coding Standards](https://www.php-fig.org/psr/psr-12/).
+
+To run CodeSniffer on tests, enter the following command:
+
+```bash
+vendor/bin/phpcs
+```
+
+Any errors should be corrected by either:
+- making applicable code changes
+- (Experimental) running `vendor/bin/phpcbf` to automatically fix coding standards
+
+Need to change the coding standard rules applied?  Either:
+- ignore a rule in the affected code, by adding `phpcs:ignore {rule}`, where {rule} is the given rule that failed in the above output.
+- edit the [phpcs.tests.xml](phpcs.xml) file.
+
+**Rules can be ignored with caution**, but it's essential that rules relating to coding style and inline code commenting / docblocks remain.
+
 ## Run PHP CodeSniffer for Tests
 
 [PHP_CodeSniffer](https://github.com/squizlabs/PHP_CodeSniffer) checks that all test code meets the [PSR-12 Coding Standards](https://www.php-fig.org/psr/psr-12/).

tests/ConvertKitAPITest.php

@@ -109,7 +109,10 @@ public function testGetSequenceSubscriptions()
         $this->assertIsArray($result['subscriptions']);
 
         // Assert sort order is ascending.
-        $this->assertGreaterThan($result['subscriptions'][0]->created_at, $result['subscriptions'][1]->created_at);
+        $this->assertGreaterThanOrEqual(
+            $result['subscriptions'][0]->created_at,
+            $result['subscriptions'][1]->created_at
+        );
     }
 
     /**
@@ -134,7 +137,10 @@ public function testGetSequenceSubscriptionsWithDescSortOrder()
         $this->assertIsArray($result['subscriptions']);
 
         // Assert sort order.
-        $this->assertLessThan($result['subscriptions'][0]->created_at, $result['subscriptions'][1]->created_at);
+        $this->assertLessThanOrEqual(
+            $result['subscriptions'][0]->created_at,
+            $result['subscriptions'][1]->created_at
+        );
     }
 
     /**