refactor: update phpunit setup and example test

Signed-off-by: Bart Jaskulski <bjaskulski@protonmail.com>

phpunit-integration.xml

@@ -2,7 +2,7 @@
          backupGlobals="false"
      >
     <testsuites>
-        <testsuite>
+        <testsuite name="Integration">
             <directory prefix="test-" suffix=".php">./tests/integration</directory>
         </testsuite>
     </testsuites>

phpunit-unit.xml

 <phpunit bootstrap="tests/unit/bootstrap.php">
     <testsuites>
-        <testsuite>
+        <testsuite name="Unit">
             <directory suffix="Test.php">./tests/unit/</directory>
         </testsuite>
     </testsuites>

tests/unit/ExampleTest.php

@@ -9,14 +9,14 @@ use WP_Mock\Tools\TestCase;
 class ExampleTest extends TestCase {
 	// private $test_class_under_tests;
 
-	public function setUp() {
+	public function setUp(): void {
 		WP_Mock::setUp();
 
 //		$example = Mockery::mock( class );
 //		$this->test_class_under_tests =
 	}
 
-	public function tearDown() {
+	public function tearDown(): void {
 		WP_Mock::tearDown();
 	}
 //