Update Model __isset and add tests

Author: MGatner

system/Model.php

@@ -1643,7 +1643,7 @@ public function __get(string $name)
 	 */
 	public function __isset(string $name): bool
 	{
-		if (in_array($name, ['primaryKey', 'table', 'returnType', 'DBGroup']))
+		if (property_exists($this, $name))
 		{
 			return true;
 		}

tests/system/Database/Live/ModelTest.php

@@ -1735,4 +1735,71 @@ public function testSoftDeleteWithTableJoinsFirst()
 		// Just making sure it didn't throw ambiguous deleted error
 		$this->assertEquals(1, $results->id);
 	}
+
+	//--------------------------------------------------------------------
+
+	public function testMagicIssetTrue()
+	{
+		$model = new UserModel();
+
+		$this->assertTrue(isset($model->table));
+	}
+
+	public function testMagicIssetFalse()
+	{
+		$model = new UserModel();
+
+		$this->assertFalse(isset($model->foobar));
+	}
+
+	public function testMagicIssetWithNewProperty()
+	{
+		$model = new UserModel();
+
+		$model->flavor = 'chocolate';
+
+		$this->assertTrue(isset($model->flavor));
+	}
+
+	public function testMagicIssetFromDb()
+	{
+		$model = new UserModel();
+
+		$this->assertTrue(isset($model->DBPrefix));
+	}
+
+	public function testMagicIssetFromBuilder()
+	{
+		$model = new UserModel();
+
+		$this->assertTrue(isset($model->canLimitDeletes));
+	}
+
+	public function testMagicGet()
+	{
+		$model = new UserModel();
+
+		$this->assertEquals('user', $model->table);
+	}
+
+	public function testMagicGetMissing()
+	{
+		$model = new UserModel();
+
+		$this->assertNull($model->foobar);
+	}
+
+	public function testMagicGetFromDB()
+	{
+		$model = new UserModel();
+
+		$this->assertEquals('utf8', $model->charset);
+	}
+
+	public function testMagicGetFromBuilder()
+	{
+		$model = new UserModel();
+
+		$this->assertIsBool($model->canLimitDeletes);
+	}
 }