Migrate to namespaced tests (Requires PHPUnit > 5.7)

Author: mikehaertl

tests/BootstrapTest.php

@@ -1,7 +1,7 @@
 <?php
 use codemix\yii2confload\Config;
 
-class BootstrapTest extends \PHPUnit_Framework_TestCase
+class BootstrapTest extends \PHPUnit\Framework\TestCase
 {
     public function testCanBootstrapApplication()
     {

tests/ConsoleConfigTest.php

@@ -1,7 +1,7 @@
 <?php
 use codemix\yii2confload\Config;
 
-class ConsoleConfigTest extends \PHPUnit_Framework_TestCase
+class ConsoleConfigTest extends \PHPUnit\Framework\TestCase
 {
     public function testCanGetConfig()
     {

tests/EnvTest.php

@@ -1,7 +1,7 @@
 <?php
 use codemix\yii2confload\Config;
 
-class EnvTest extends \PHPUnit_Framework_TestCase
+class EnvTest extends \PHPUnit\Framework\TestCase
 {
     public function testCanInitYiiEnvFromEnvVars()
     {

tests/WebConfigTest.php

@@ -1,7 +1,7 @@
 <?php
 use codemix\yii2confload\Config;
 
-class WebConfigTest extends \PHPUnit_Framework_TestCase
+class WebConfigTest extends \PHPUnit\Framework\TestCase
 {
     public function testCanGetConfig()
     {