improve code style

tests/unit/ConnectionTest.php

@@ -198,7 +198,7 @@ class ConnectionTest extends TestCase
             $this->callMethod(
                 $sutMock,
                 'requestAndParse',
-                ['POST', 'endpoint.php', ['options'=>'']]
+                ['POST', 'endpoint.php', ['options' => '']]
             )
         );
     }
@@ -223,7 +223,7 @@ class ConnectionTest extends TestCase
             ->setConstructorArgs([$status, [], $content])
             ->onlyMethods(['getStatusCode'])
             ->getMock();
-        $responseMock->method('getStatusCode')->willReturn( $status);
+        $responseMock->method('getStatusCode')->willReturn($status);
 
         if ($expectException) {
             $this->expectException(ResponseContentException::class);

tests/unit/KlicktippTest.php

@@ -119,7 +119,7 @@ class KlicktippTest extends TestCase
      * @covers \D3\KlicktippPhpClient\Klicktipp::tag
      * @dataProvider instanceGetterDataProvider
      */
-    public function testInstanceGetter(string $testMethodName, string $expectedClassName)
+    public function testInstanceGetter(string $testMethodName, string $expectedClassName): void
     {
         $connectionMock = $this->getMockBuilder(Connection::class)
             ->disableOriginalConstructor()