test: add test for NOT NULL columns

Author: kenjis

tests/system/Database/Live/ForgeTest.php

@@ -1277,7 +1277,7 @@ public function testModifyColumnRename()
         $this->forge->dropTable('forge_test_three', true);
     }
 
-    public function testModifyColumnNull()
+    public function testModifyColumnNullTrue()
     {
         if ($this->db->DBDriver === 'SQLSRV') {
             $this->markTestSkipped('SQLSRV does not support getFieldData() nullable.');
@@ -1310,6 +1310,39 @@ public function testModifyColumnNull()
         $this->forge->dropTable('forge_test_modify', true);
     }
 
+    public function testModifyColumnNullFalse()
+    {
+        if ($this->db->DBDriver === 'SQLSRV') {
+            $this->markTestSkipped('SQLSRV does not support getFieldData() nullable.');
+        }
+
+        $this->forge->dropTable('forge_test_modify', true);
+
+        $this->forge->addField([
+            'col1' => ['type' => 'VARCHAR', 'constraint' => 255, 'null' => false],
+            'col2' => ['type' => 'VARCHAR', 'constraint' => 255, 'null' => false],
+            'col3' => ['type' => 'VARCHAR', 'constraint' => 255, 'null' => false],
+        ]);
+        $this->forge->createTable('forge_test_modify');
+
+        $this->forge->modifyColumn('forge_test_modify', [
+            'col1' => ['type' => 'VARCHAR', 'constraint' => 1],
+            'col2' => ['type' => 'VARCHAR', 'constraint' => 1, 'null' => true],
+            'col3' => ['type' => 'VARCHAR', 'constraint' => 1, 'null' => false],
+        ]);
+
+        $this->db->resetDataCache();
+
+        $col1 = $this->getMetaData('col1', 'forge_test_modify');
+        $this->assertTrue($col1->nullable); // Nullable if not specified.
+        $col2 = $this->getMetaData('col2', 'forge_test_modify');
+        $this->assertTrue($col2->nullable);
+        $col3 = $this->getMetaData('col3', 'forge_test_modify');
+        $this->assertFalse($col3->nullable);
+
+        $this->forge->dropTable('forge_test_modify', true);
+    }
+
     private function getMetaData(string $column, string $table): stdClass
     {
         $fields = $this->db->getFieldData($table);