Update test suite to PHPUnit 7 and legacy PHPUnit versions

Author: clue

composer.json

@@ -9,7 +9,7 @@
         "php": ">=5.4.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.8"
+        "phpunit/phpunit": "^7.0 || ^6.5 || ^5.7 || ^4.8.36"
     },
     "autoload": {
         "psr-4": {
@@ -19,7 +19,7 @@
     },
     "autoload-dev": {
         "psr-4": {
-            "React\\Promise\\": "tests/fixtures"
+            "React\\Promise\\": ["tests", "tests/fixtures"]
         }
     },
     "keywords": [

phpunit.xml.dist

@@ -8,8 +8,7 @@
          convertWarningsToExceptions="true"
          processIsolation="false"
          stopOnFailure="false"
-         syntaxCheck="false"
-         bootstrap="tests/bootstrap.php"
+         bootstrap="vendor/autoload.php"
 >
     <testsuites>
         <testsuite name="Promise Test Suite">

tests/Stub/CallableStub.php

@@ -2,7 +2,7 @@
 
 namespace React\Promise;
 
-class TestCase extends \PHPUnit_Framework_TestCase
+class TestCase extends \PHPUnit\Framework\TestCase
 {
     public function expectCallableExactly($amount)
     {
@@ -36,8 +36,23 @@ public function expectCallableNever()
 
     public function createCallableMock()
     {
-        return $this
-            ->getMockBuilder('React\\Promise\Stub\CallableStub')
-            ->getMock();
+        return $this->getMockBuilder('stdClass')->setMethods(array('__invoke'))->getMock();
+    }
+
+    public function setExpectedException($exception, $exceptionMessage = '', $exceptionCode = null)
+    {
+        if (method_exists($this, 'expectException')) {
+            // PHPUnit 5+
+            $this->expectException($exception);
+            if ($exceptionMessage !== '') {
+                $this->expectExceptionMessage($exceptionMessage);
+            }
+            if ($exceptionCode !== null) {
+                $this->expectExceptionCode($exceptionCode);
+            }
+        } else {
+            // legacy PHPUnit 4
+            parent::setExpectedException($exception, $exceptionMessage, $exceptionCode);
+        }
     }
 }