public function testPublishAlteredMessage() { $args = ['Message' => $originalMessage = 'MyOriginalMessage']; $this->snsClient->method('__call')->with('publish')->willReturnCallback(function ($name, array $args) use($originalMessage) { $params = array_key_exists(0, $args) ? $args[0] : []; \PHPUnit_Framework_Assert::assertNotEquals($originalMessage, $params['Message']); return new Result(); }); $actual = $this->sut->publish($args); self::assertInstanceOf(Result::class, $actual); }