public function testIsConsumer() { $this->assertFalse(Callables::isConsumer(Callables::newSupplier(function () { return null; }))); $this->assertFalse(Callables::isConsumer(Callables::newFunktion(function () { return null; }))); $this->assertFalse(Callables::isConsumer(Callables::newPredicate(function () { return null; }))); $this->assertTrue(Callables::isConsumer(Callables::newConsumer(function () { return null; }))); }