MRSH-1024 add custom markup to get exchange rate methods (#6)

## Added

- exchange rate custom markup to config `SHIPPER_EXCHANGE_RATE_MARKUP_PERCENT` and `getRate` method [(MRSH-1024)](https://ego-digital.atlassian.net/browse/MRSH-1024);

Author: alexey-krivoshapko

README.md

@@ -37,6 +37,7 @@ Optional:
 
     SHIPPER_EXCHANGE_RATE_FROM="EUR,USD"
     SHIPPER_EXCHANGE_RATE_TO="EUR,USD"
+    SHIPPER_EXCHANGE_RATE_MARKUP_PERCENT=5
 
 
 ## Usage

config/shipper-exchange-rate.php

@@ -8,4 +8,6 @@
     'from' => env('SHIPPER_EXCHANGE_RATE_FROM', ['EUR', 'USD', 'ILS']),
 
     'to' => env('SHIPPER_EXCHANGE_RATE_TO', ['EUR', 'USD']),
+
+    'markup_percent' => env('SHIPPER_EXCHANGE_RATE_MARKUP_PERCENT', 0),
 ];

src/ShipperExchangeRate.php

@@ -56,8 +56,17 @@ public function getRate(string $from, string $to): float
                 $this->callAutoFetchCallback($from, $to);
             }
         }
+        return  $this->getRateWithMarkup($rate);
+    }
 
-        return  $rate;
+    /**
+     * @param float $rate
+     * @return float
+     */
+    public function getRateWithMarkup(float $rate): float
+    {
+        $markup = config('shipper-exchange-rate.markup_percent', 0);
+        return $rate + ($rate * $markup / 100);
     }
 
     /**

tests/SrcTest.php

@@ -66,4 +66,21 @@ public function auto_add_currency(): void
         $this->assertGreaterThan(0, $rate);
         $this->assertEquals(['UAH', 'USD'], $test);
     }
+
+    /**
+     * @test
+     * @return void
+     * @throws RatePairNotFoundException
+     */
+    public function auto_add_currency_with_markup(): void
+    {
+        $exchange_rate_markup = 7.25;
+        config(['shipper-exchange-rate.markup_percent' => $exchange_rate_markup]);
+        $service = new ShipperExchangeRate();
+        $this->assertEquals(0, DB::table('shipper_exchange_rates')->count());
+        $rate = $service->getRate('UAH', 'USD');
+        $this->assertGreaterThan(0, $rate);
+        $origin_rate = $service->retrieveRate('UAH', 'USD');
+        $this->assertEquals($exchange_rate_markup, $rate / $origin_rate * 100 - 100);
+    }
 }