diff --git a/core/lib/Drupal/Component/Annotation/composer.json b/core/lib/Drupal/Component/Annotation/composer.json
index c384473c08..1bfd04fa8d 100644
--- a/core/lib/Drupal/Component/Annotation/composer.json
+++ b/core/lib/Drupal/Component/Annotation/composer.json
@@ -12,6 +12,9 @@
     "drupal/core-plugin": "^8.5",
     "drupal/core-utility": "^8.2"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Annotation\\": ""
diff --git a/core/lib/Drupal/Component/Assertion/composer.json b/core/lib/Drupal/Component/Assertion/composer.json
index cdc8c928fb..e39c01373e 100644
--- a/core/lib/Drupal/Component/Assertion/composer.json
+++ b/core/lib/Drupal/Component/Assertion/composer.json
@@ -7,6 +7,9 @@
   "require": {
     "php": ">=5.5.9"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Assertion\\": ""
diff --git a/core/lib/Drupal/Component/Bridge/composer.json b/core/lib/Drupal/Component/Bridge/composer.json
index a8666aa88c..583cd300e1 100644
--- a/core/lib/Drupal/Component/Bridge/composer.json
+++ b/core/lib/Drupal/Component/Bridge/composer.json
@@ -9,6 +9,9 @@
     "symfony/dependency-injection": ">=3.0.0 <4.0.0",
     "zendframework/zend-feed": "^2.4"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Bridge\\": ""
diff --git a/core/lib/Drupal/Component/ClassFinder/composer.json b/core/lib/Drupal/Component/ClassFinder/composer.json
index c5a97b09f1..23a9161bbf 100644
--- a/core/lib/Drupal/Component/ClassFinder/composer.json
+++ b/core/lib/Drupal/Component/ClassFinder/composer.json
@@ -8,6 +8,9 @@
     "php": ">=5.5.9",
     "doctrine/common": "^2.5"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\ClassFinder\\": ""
diff --git a/core/lib/Drupal/Component/Datetime/composer.json b/core/lib/Drupal/Component/Datetime/composer.json
index cb41803a8a..2bc2095410 100644
--- a/core/lib/Drupal/Component/Datetime/composer.json
+++ b/core/lib/Drupal/Component/Datetime/composer.json
@@ -9,6 +9,7 @@
     "drupal/core-utility": "^8.2"
   },
   "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5",
     "symfony/http-foundation": ">=3.0.0 <4.0.0"
   },
   "autoload": {
diff --git a/core/lib/Drupal/Component/DependencyInjection/composer.json b/core/lib/Drupal/Component/DependencyInjection/composer.json
index c890a34267..8988c50092 100644
--- a/core/lib/Drupal/Component/DependencyInjection/composer.json
+++ b/core/lib/Drupal/Component/DependencyInjection/composer.json
@@ -15,7 +15,8 @@
     "symfony/dependency-injection": ">=3.3.0 <4.0.0"
   },
   "require-dev": {
-    "drupal/core-utility": "^8.1@dev"
+    "drupal/core-utility": "^8.1@dev",
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
   },
   "suggest": {
     "symfony/expression-language": "For using expressions in service container configuration"
diff --git a/core/lib/Drupal/Component/Diff/composer.json b/core/lib/Drupal/Component/Diff/composer.json
index b3016084a2..4be8174d41 100644
--- a/core/lib/Drupal/Component/Diff/composer.json
+++ b/core/lib/Drupal/Component/Diff/composer.json
@@ -8,6 +8,9 @@
     "php": ">=5.5.9",
     "symfony/polyfill-mbstring": "~1.0"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Diff\\": ""
diff --git a/core/lib/Drupal/Component/Discovery/composer.json b/core/lib/Drupal/Component/Discovery/composer.json
index cb9b29b0df..68b20486c1 100644
--- a/core/lib/Drupal/Component/Discovery/composer.json
+++ b/core/lib/Drupal/Component/Discovery/composer.json
@@ -12,7 +12,8 @@
     "symfony/yaml": ">=3.3 <4.0.0"
   },
   "require-dev": {
-    "mikey179/vfsStream": "^1.2"
+    "mikey179/vfsStream": "^1.2",
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
   },
   "autoload": {
     "psr-4": {
diff --git a/core/lib/Drupal/Component/EventDispatcher/composer.json b/core/lib/Drupal/Component/EventDispatcher/composer.json
index f10d4f422c..78e8994723 100644
--- a/core/lib/Drupal/Component/EventDispatcher/composer.json
+++ b/core/lib/Drupal/Component/EventDispatcher/composer.json
@@ -9,6 +9,9 @@
     "symfony/dependency-injection": ">=2.8 <4.0.0",
     "symfony/event-dispatcher": ">=3.4 <4.0.0"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\EventDispatcher\\": ""
diff --git a/core/lib/Drupal/Component/FileCache/composer.json b/core/lib/Drupal/Component/FileCache/composer.json
index ac4f387c56..c950ad20a6 100644
--- a/core/lib/Drupal/Component/FileCache/composer.json
+++ b/core/lib/Drupal/Component/FileCache/composer.json
@@ -8,7 +8,8 @@
     "php": ">=5.5.9"
   },
   "require-dev": {
-    "drupal/core-utility": "^8.1@dev"
+    "drupal/core-utility": "^8.1@dev",
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
   },
   "autoload": {
     "psr-4": {
diff --git a/core/lib/Drupal/Component/FileSystem/composer.json b/core/lib/Drupal/Component/FileSystem/composer.json
index 084e991766..a4d689831e 100644
--- a/core/lib/Drupal/Component/FileSystem/composer.json
+++ b/core/lib/Drupal/Component/FileSystem/composer.json
@@ -8,7 +8,8 @@
     "php": ">=5.5.9"
   },
   "require-dev": {
-    "mikey179/vfsStream": "^1.2"
+    "mikey179/vfsStream": "^1.2",
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
   },
   "autoload": {
     "psr-4": {
diff --git a/core/lib/Drupal/Component/Gettext/composer.json b/core/lib/Drupal/Component/Gettext/composer.json
index a3744575a5..4db29cb7fb 100644
--- a/core/lib/Drupal/Component/Gettext/composer.json
+++ b/core/lib/Drupal/Component/Gettext/composer.json
@@ -13,7 +13,8 @@
     "drupal/core-utility": "^8.2"
   },
   "require-dev": {
-    "mikey179/vfsStream": "^1.2"
+    "mikey179/vfsStream": "^1.2",
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
   },
   "autoload": {
     "psr-4": {
diff --git a/core/lib/Drupal/Component/Graph/composer.json b/core/lib/Drupal/Component/Graph/composer.json
index e8f645fd20..3c8dcd85b4 100644
--- a/core/lib/Drupal/Component/Graph/composer.json
+++ b/core/lib/Drupal/Component/Graph/composer.json
@@ -7,6 +7,9 @@
   "require": {
     "php": ">=5.5.9"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Graph\\": ""
diff --git a/core/lib/Drupal/Component/HttpFoundation/composer.json b/core/lib/Drupal/Component/HttpFoundation/composer.json
index 910a648a21..29c6dd60e2 100644
--- a/core/lib/Drupal/Component/HttpFoundation/composer.json
+++ b/core/lib/Drupal/Component/HttpFoundation/composer.json
@@ -8,6 +8,9 @@
     "php": ">=5.5.9",
     "symfony/http-foundation": ">=2.7 <4.0.0"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\HttpFoundation\\": ""
diff --git a/core/lib/Drupal/Component/PhpStorage/composer.json b/core/lib/Drupal/Component/PhpStorage/composer.json
index af7f1353c3..fb1c2c3df5 100644
--- a/core/lib/Drupal/Component/PhpStorage/composer.json
+++ b/core/lib/Drupal/Component/PhpStorage/composer.json
@@ -9,7 +9,8 @@
   },
   "require-dev": {
     "drupal/core-utility": "^8.1@dev",
-    "mikey179/vfsStream": "^1.2"
+    "mikey179/vfsStream": "^1.2",
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
   },
   "autoload": {
     "psr-4": {
diff --git a/core/lib/Drupal/Component/Plugin/composer.json b/core/lib/Drupal/Component/Plugin/composer.json
index 77f02d6fb1..5b5ffef6ba 100644
--- a/core/lib/Drupal/Component/Plugin/composer.json
+++ b/core/lib/Drupal/Component/Plugin/composer.json
@@ -8,6 +8,9 @@
     "php": ">=5.5.9",
     "symfony/validator": ">=2.7 <4.0.0"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Plugin\\": ""
diff --git a/core/lib/Drupal/Component/ProxyBuilder/composer.json b/core/lib/Drupal/Component/ProxyBuilder/composer.json
index 52fbdb8065..7e449d298b 100644
--- a/core/lib/Drupal/Component/ProxyBuilder/composer.json
+++ b/core/lib/Drupal/Component/ProxyBuilder/composer.json
@@ -7,6 +7,9 @@
   "require": {
     "php": ">=5.5.9"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\ProxyBuilder\\": ""
diff --git a/core/lib/Drupal/Component/Render/composer.json b/core/lib/Drupal/Component/Render/composer.json
index 9e44b2dd39..55a1e2fa0b 100644
--- a/core/lib/Drupal/Component/Render/composer.json
+++ b/core/lib/Drupal/Component/Render/composer.json
@@ -8,6 +8,9 @@
     "php": ">=5.5.9",
     "drupal/core-utility": "^8.2"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Render\\": ""
diff --git a/core/lib/Drupal/Component/Serialization/composer.json b/core/lib/Drupal/Component/Serialization/composer.json
index eee28ec3e6..cb7462a580 100644
--- a/core/lib/Drupal/Component/Serialization/composer.json
+++ b/core/lib/Drupal/Component/Serialization/composer.json
@@ -8,6 +8,9 @@
     "php": ">=5.5.9",
     "symfony/yaml": ">=3.3 <4.0.0"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Serialization\\": ""
diff --git a/core/lib/Drupal/Component/Transliteration/composer.json b/core/lib/Drupal/Component/Transliteration/composer.json
index fd900e54db..1809008747 100644
--- a/core/lib/Drupal/Component/Transliteration/composer.json
+++ b/core/lib/Drupal/Component/Transliteration/composer.json
@@ -10,7 +10,8 @@
   },
   "require-dev": {
     "drupal/core-utility": "^8.1@dev",
-    "mikey179/vfsStream": "^1.2"
+    "mikey179/vfsStream": "^1.2",
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
   },
   "autoload": {
     "psr-4": {
diff --git a/core/lib/Drupal/Component/Utility/composer.json b/core/lib/Drupal/Component/Utility/composer.json
index b17d142393..4c69dc4efd 100644
--- a/core/lib/Drupal/Component/Utility/composer.json
+++ b/core/lib/Drupal/Component/Utility/composer.json
@@ -12,7 +12,8 @@
     "symfony/polyfill-mbstring": "~1.0"
   },
   "require-dev": {
-    "drupal/core-assertion": "^8.2"
+    "drupal/core-assertion": "^8.2",
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
   },
   "autoload": {
     "psr-4": {
diff --git a/core/lib/Drupal/Component/Uuid/composer.json b/core/lib/Drupal/Component/Uuid/composer.json
index 8e9cced871..4a346561b3 100644
--- a/core/lib/Drupal/Component/Uuid/composer.json
+++ b/core/lib/Drupal/Component/Uuid/composer.json
@@ -12,6 +12,9 @@
     "php": ">=5.5.9",
     "drupal/core-utility": "^8.2"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^4.8.35 || ^6.5"
+  },
   "autoload": {
     "psr-4": {
       "Drupal\\Component\\Uuid\\": ""