Fix coding style in tests

Author: geerteltink

test/ConfigProviderTest.php

@@ -27,7 +27,7 @@ protected function setUp() : void
     public function testInvocationReturnsArray() : array
     {
         $config = ($this->provider)();
-        self::assertInternalType('array', $config);
+        $this->assertInternalType('array', $config);
 
         return $config;
     }
@@ -37,8 +37,8 @@ public function testInvocationReturnsArray() : array
      */
     public function testReturnedArrayContainsDependencies(array $config) : void
     {
-        self::assertArrayHasKey('dependencies', $config);
-        self::assertArrayHasKey('templates', $config);
-        self::assertInternalType('array', $config['dependencies']);
+        $this->assertArrayHasKey('dependencies', $config);
+        $this->assertArrayHasKey('templates', $config);
+        $this->assertInternalType('array', $config['dependencies']);
     }
 }

test/ExceptionTest.php

@@ -18,7 +18,7 @@ class ExceptionTest extends TestCase
 {
     public function testExceptionInterfaceExtendsTemplateExceptionInterface() : void
     {
-        self::assertTrue(is_a(ExceptionInterface::class, TemplateExceptionInterface::class, true));
+        $this->assertTrue(is_a(ExceptionInterface::class, TemplateExceptionInterface::class, true));
     }
 
     public function exception() : Generator
@@ -38,7 +38,7 @@ public function exception() : Generator
      */
     public function testExceptionIsInstanceOfExceptionInterface(string $exception) : void
     {
-        self::assertContains('Exception', $exception);
-        self::assertTrue(is_a($exception, ExceptionInterface::class, true));
+        $this->assertContains('Exception', $exception);
+        $this->assertTrue(is_a($exception, ExceptionInterface::class, true));
     }
 }