public function testError() { $math = new Math(); // no input try { $math->add(); } catch (\Exception $e) { $this->assertEquals('Please provide numbers to add', $e->getMessage()); } // no input try { $math->subtract(); } catch (\Exception $e) { $this->assertEquals('Please provide numbers to subtract', $e->getMessage()); } // no input try { $math->multiply(); } catch (\Exception $e) { $this->assertEquals('Please provide numbers to multiply', $e->getMessage()); } // no input try { $math->divide(); } catch (\Exception $e) { $this->assertEquals('Please provide numbers to divide', $e->getMessage()); } //invalid input try { $math->setA('adf'); } catch (\Exception $e) { $this->assertEquals('Invalid input', $e->getMessage()); } }