Test enhancement

[peter279k]

Changed log

• Using current assertions to assert the expected and result values.
• Removing additional white spaces.
• To be consistency, using the use syntax to declare required namespaces on the beginning of PHP file.
• Using the magic ::class syntax to assert instance is expected.
• According to official PHPUnit doc, the setUp and tearDown fixture methods are protected, not public.

[peter279k]

Since the PHPUnit uses the 6.4 version at least, the default PHPUnit namespace is PHPUnit\Framework\TestCase.

The class_alias and class checking are not necessary.