Add test for #2731

tests/Regression/GitHub/2731.phpt

@@ -0,0 +1,26 @@
+--TEST--
+GH-2731: Empty exception message cannot be expected
+--FILE--
+<?php
+$_SERVER['argv'][1] = '--no-configuration';
+$_SERVER['argv'][2] = 'Issue2731Test';
+$_SERVER['argv'][3] = __DIR__ . '/2731/Issue2731Test.php';
+
+require __DIR__ . '/../../bootstrap.php';
+
+PHPUnit_TextUI_Command::main();
+?>
+--EXPECTF--
+PHPUnit %s by Sebastian Bergmann and contributors.
+
+F                                                                   1 / 1 (100%)
+
+Time: %s, Memory: %s
+
+There was 1 failure:
+
+1) Issue2731Test::testOne
+Failed asserting that exception message is empty but is 'message'.
+
+FAILURES!
+Tests: 1, Assertions: 2, Failures: 1.

tests/Regression/GitHub/2731/Issue2731Test.php

@@ -0,0 +1,11 @@
+<?php
+class Issue2731Test extends PHPUnit\Framework\TestCase
+{
+    public function testOne()
+    {
+        $this->expectException(Exception::class);
+        $this->expectExceptionMessage('');
+
+        throw new Exception('message');
+    }
+}