MathTest.php

<?php
namespace Tests\Integration;

use Tests\TestCase;

class MathTest extends TestCase
{
    public function setUp()
    {
        parent::setUp();

        $this->math = $this->app->make('App\Math');
    }

    public function test_getArea_WhenCalledWithLength2_Return4()
    {
        $response = $this->math->getArea(2);

        $this->assertTrue(is_int($response));
        $this->assertEquals(4, $response);
    }

    public function test_getArea_WhenCalledWithLength6_Return36()
    {
        $length = 6;

        $response = $this->math->getArea($length);

        $this->assertTrue(is_int($response));
        $this->assertEquals(36, $response);
    }

    public function test_getArea_WhenCalledWithoutLength_ThrowAnException()
    {
        $this->expectException('ArgumentCountError');
        $this->expectExceptionMessage('Too few arguments to function');

        $this->math->getArea();
    }

}