diff --git a/composer.json b/composer.json
index bcaaed20348c..3c76467d8010 100644
--- a/composer.json
+++ b/composer.json
@@ -86,7 +86,7 @@
         "moontoast/math": "^1.1",
         "orchestra/testbench-core": "^4.0",
         "pda/pheanstalk": "^4.0",
-        "phpunit/phpunit": "^8.4|^9.0",
+        "phpunit/phpunit": "^7.5.15|^8.4|^9.0",
         "predis/predis": "^1.1.1",
         "symfony/cache": "^4.3.4"
     },
diff --git a/src/Illuminate/Foundation/Testing/Assert.php b/src/Illuminate/Foundation/Testing/Assert.php
index 3a35bebe8852..f4075ab48f96 100644
--- a/src/Illuminate/Foundation/Testing/Assert.php
+++ b/src/Illuminate/Foundation/Testing/Assert.php
@@ -6,42 +6,65 @@
 use Illuminate\Foundation\Testing\Constraints\ArraySubset;
 use PHPUnit\Framework\Assert as PHPUnit;
 use PHPUnit\Framework\InvalidArgumentException;
+use PHPUnit\Runner\Version;
 use PHPUnit\Util\InvalidArgumentHelper;
 
-/**
- * @internal This class is not meant to be used or overwritten outside the framework itself.
- */
-abstract class Assert extends PHPUnit
-{
+if (class_exists(Version::class) && (int) Version::series()[0] >= 8) {
     /**
-     * Asserts that an array has a specified subset.
-     *
-     * @param  \ArrayAccess|array  $subset
-     * @param  \ArrayAccess|array  $array
-     * @param  bool  $checkForIdentity
-     * @param  string  $msg
-     * @return void
+     * @internal This class is not meant to be used or overwritten outside the framework itself.
      */
-    public static function assertArraySubset($subset, $array, bool $checkForIdentity = false, string $msg = ''): void
+    abstract class Assert extends PHPUnit
     {
-        if (! (is_array($subset) || $subset instanceof ArrayAccess)) {
-            if (class_exists(InvalidArgumentException::class)) {
-                throw InvalidArgumentException::create(1, 'array or ArrayAccess');
-            } else {
-                throw InvalidArgumentHelper::factory(1, 'array or ArrayAccess');
+        /**
+         * Asserts that an array has a specified subset.
+         *
+         * @param  \ArrayAccess|array  $subset
+         * @param  \ArrayAccess|array  $array
+         * @param  bool  $checkForIdentity
+         * @param  string  $msg
+         * @return void
+         */
+        public static function assertArraySubset($subset, $array, bool $checkForIdentity = false, string $msg = ''): void
+        {
+            if (! (is_array($subset) || $subset instanceof ArrayAccess)) {
+                if (class_exists(InvalidArgumentException::class)) {
+                    throw InvalidArgumentException::create(1, 'array or ArrayAccess');
+                } else {
+                    throw InvalidArgumentHelper::factory(1, 'array or ArrayAccess');
+                }
             }
-        }
 
-        if (! (is_array($array) || $array instanceof ArrayAccess)) {
-            if (class_exists(InvalidArgumentException::class)) {
-                throw InvalidArgumentException::create(2, 'array or ArrayAccess');
-            } else {
-                throw InvalidArgumentHelper::factory(2, 'array or ArrayAccess');
+            if (! (is_array($array) || $array instanceof ArrayAccess)) {
+                if (class_exists(InvalidArgumentException::class)) {
+                    throw InvalidArgumentException::create(2, 'array or ArrayAccess');
+                } else {
+                    throw InvalidArgumentHelper::factory(2, 'array or ArrayAccess');
+                }
             }
-        }
 
-        $constraint = new ArraySubset($subset, $checkForIdentity);
+            $constraint = new ArraySubset($subset, $checkForIdentity);
 
-        PHPUnit::assertThat($array, $constraint, $msg);
+            PHPUnit::assertThat($array, $constraint, $msg);
+        }
+    }
+} else {
+    /**
+     * @internal This class is not meant to be used or overwritten outside the framework itself.
+     */
+    abstract class Assert extends PHPUnit
+    {
+        /**
+         * Asserts that an array has a specified subset.
+         *
+         * @param  \ArrayAccess|array  $subset
+         * @param  \ArrayAccess|array  $array
+         * @param  bool  $checkForIdentity
+         * @param  string  $msg
+         * @return void
+         */
+        public static function assertArraySubset($subset, $array, bool $checkForIdentity = false, string $msg = ''): void
+        {
+            PHPUnit::assertArraySubset($subset, $array, $checkForIdentity, $msg);
+        }
     }
 }
diff --git a/src/Illuminate/Foundation/Testing/Constraints/ArraySubset.php b/src/Illuminate/Foundation/Testing/Constraints/ArraySubset.php
index edfbf96d4ea6..9d07f461523a 100644
--- a/src/Illuminate/Foundation/Testing/Constraints/ArraySubset.php
+++ b/src/Illuminate/Foundation/Testing/Constraints/ArraySubset.php
@@ -143,7 +143,7 @@ private function toArray(iterable $other): array
             return (array) $other;
         }
     }
-} else {
+} elseif (class_exists(Version::class) && (int) Version::series()[0] >= 8) {
     /**
      * @internal This class is not meant to be used or overwritten outside the framework itself.
      */
diff --git a/tests/Foundation/FoundationProviderRepositoryTest.php b/tests/Foundation/FoundationProviderRepositoryTest.php
index 06402d8685a2..c6c0095028b6 100755
--- a/tests/Foundation/FoundationProviderRepositoryTest.php
+++ b/tests/Foundation/FoundationProviderRepositoryTest.php
@@ -92,7 +92,12 @@ public function testWriteManifestStoresToProperLocation()
     public function testWriteManifestThrowsExceptionIfManifestDirDoesntExist()
     {
         $this->expectException(Exception::class);
-        $this->expectExceptionMessageMatches('/^The (.*) directory must be present and writable.$/');
+
+        if (is_callable([$this, 'expectExceptionMessageMatches'])) {
+            $this->expectExceptionMessageMatches('/^The (.*) directory must be present and writable.$/');
+        } else {
+            $this->expectExceptionMessageRegExp('/^The (.*) directory must be present and writable.$/');
+        }
 
         $repo = new ProviderRepository(m::mock(ApplicationContract::class), $files = m::mock(Filesystem::class), __DIR__.'/cache/services.php');
         $files->shouldReceive('replace')->never();