Merge branch 'master' into 5.5

Author: dmitry-ivanov

README.md

@@ -412,7 +412,7 @@ $decoded = is_json('{"foo":1,"bar":2,"baz":3}', true);
 
 #### `str_lower()`
 
-Converts string to lowercase:
+Converts string to lowercase, using `mb_strtolower` in `UTF-8` encoding:
 
 ```php
 $lower = str_lower('TeSt');
@@ -422,7 +422,7 @@ $lower = str_lower('TeSt');
 
 #### `str_upper()`
 
-Converts string to uppercase:
+Converts string to uppercase, using `mb_strtoupper` in `UTF-8` encoding:
 
 ```php
 $upper = str_upper('TeSt');

composer.json

@@ -22,7 +22,7 @@
     "require-dev": {
         "phpunit/phpunit": "^6.0",
         "mockery/mockery": "^0.9",
-        "illuminated/testing-tools": "^0.6"
+        "illuminated/testing-tools": "5.5.*"
     },
     "autoload": {
         "files": ["src/autoload.php"],

composer.lock

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit backupGlobals="false"
          backupStaticAttributes="false"
+         beStrictAboutTestsThatDoNotTestAnything="false"
          bootstrap="vendor/autoload.php"
          colors="true"
          convertErrorsToExceptions="true"