Merge branch '4.4'

* 4.4:
  [Bridge/PhpUnit] cleanup fix
  [PhpUnitBridge] Add polyfill for methods assertNan, assertFinite and assertInfinite
  [Mailer] fixed wrong error message when connection closes unexpectedly
  [Mailer] added debug info to TransportExceptionInterface
  [Mailer] fixed error that is masked by another error
  [Mailer] fixed the order of authenticators

Author: nicolas-grekas

Legacy/ForwardCompatTestTraitForV5.php

@@ -87,7 +87,7 @@ private function doTearDown()
     }
 
     /**
-     * @param string $originalClassName
+     * @param string|string[] $originalClassName
      *
      * @return MockObject
      */
@@ -106,7 +106,8 @@ protected function createMock($originalClassName)
     }
 
     /**
-     * @param string $originalClassName
+     * @param string|string[] $originalClassName
+     * @param string[]        $methods
      *
      * @return MockObject
      */
@@ -235,6 +236,54 @@ public static function assertIsIterable($actual, $message = '')
         static::assertInternalType('iterable', $actual, $message);
     }
 
+    /**
+     * @param string $message
+     *
+     * @return void
+     */
+    public static function assertFinite($actual, $message = '')
+    {
+        if (\is_callable('parent::assertFinite')) {
+            parent::assertFinite($actual, $message);
+
+            return;
+        }
+        static::assertInternalType('float', $actual, $message);
+        static::assertTrue(is_finite($actual), $message ? $message : "Failed asserting that $actual is finite.");
+    }
+
+    /**
+     * @param string $message
+     *
+     * @return void
+     */
+    public static function assertInfinite($actual, $message = '')
+    {
+        if (\is_callable('parent::assertInfinite')) {
+            parent::assertInfinite($actual, $message);
+
+            return;
+        }
+        static::assertInternalType('float', $actual, $message);
+        static::assertTrue(is_infinite($actual), $message ? $message : "Failed asserting that $actual is infinite.");
+    }
+
+    /**
+     * @param string $message
+     *
+     * @return void
+     */
+    public static function assertNan($actual, $message = '')
+    {
+        if (\is_callable('parent::assertNan')) {
+            parent::assertNan($actual, $message);
+
+            return;
+        }
+        static::assertInternalType('float', $actual, $message);
+        static::assertTrue(is_nan($actual), $message ? $message : "Failed asserting that $actual is nan.");
+    }
+
     /**
      * @param string $exception
      *

Legacy/ForwardCompatTestTraitForV7.php

@@ -32,4 +32,19 @@ protected function createMock($originalClassName): MockObject
             ->disallowMockingUnknownTypes()
             ->getMock();
     }
+
+    /**
+     * @param string|string[] $originalClassName
+     * @param string[]        $methods
+     */
+    protected function createPartialMock($originalClassName, array $methods): MockObject
+    {
+        return $this->getMockBuilder($originalClassName)
+            ->disableOriginalConstructor()
+            ->disableOriginalClone()
+            ->disableArgumentCloning()
+            ->disallowMockingUnknownTypes()
+            ->setMethods(empty($methods) ? null : $methods)
+            ->getMock();
+    }
 }