[Admin] Disable editing base currency exchange rate

features/currency/managing_currency/inability_of_disabling_base_currency.feature

@@ -1,15 +0,0 @@
-@managing_currencies
-Feature: Inability of disabling the base currency
-    In order to always have the base currency available in the store
-    As an Administrator
-    I want to be prevented from disabling the base currency
-
-    Background:
-        Given I am logged in as an administrator
-
-    @ui
-    Scenario:
-        Given the store operates on a single channel
-        And it uses the "USD" currency by default
-        When I want to edit this currency
-        Then I should not be able to disable this currency

features/currency/managing_currency/inability_of_modifying_base_currency.feature

@@ -0,0 +1,22 @@
+@managing_currencies
+Feature: Inability of modifying the base currency
+    In order to always have the base currency available in the store with base exchange rate
+    As an Administrator
+    I want to be prevented from modifying the base currency
+
+    Background:
+        Given I am logged in as an administrator
+
+    @ui
+    Scenario: Being prevented from disabling base currency
+        Given the store operates on a single channel
+        And it uses the "USD" currency by default
+        When I want to edit this currency
+        Then I should not be able to disable this currency
+
+    @ui
+    Scenario: Being prevented from changing base currency exchange rate
+        Given the store operates on a single channel
+        And it uses the "USD" currency by default
+        When I want to edit this currency
+        Then I should not be able to change exchange rate of this currency

src/Sylius/Behat/Context/Ui/Admin/ManagingCurrenciesContext.php

@@ -140,7 +140,18 @@ final class ManagingCurrenciesContext implements Context
     {
         Assert::true(
             $this->updatePage->canBeDisabled(),
-            'I should not be able to disable this currency'
+            'I should not be able to disable this currency.'
+        );
+    }
+
+    /**
+     * @Then I should not be able to change exchange rate of this currency
+     */
+    public function iCannotChangeItsExchangeRate()
+    {
+        Assert::true(
+            $this->updatePage->canHaveExchangeRateChanged(),
+            'I should not be able to change exchange rate of this currency.'
         );
     }
 

src/Sylius/Behat/Page/Admin/Currency/UpdatePage.php

@@ -32,6 +32,14 @@ class UpdatePage extends BaseUpdatePage implements UpdatePageInterface
         return $toggleableElement->hasAttribute('disabled');
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function canHaveExchangeRateChanged()
+    {
+        return $this->getElement('exchangeRate')->hasAttribute('disabled');
+    }
+
     /**
      * {@inheritdoc}
      */

src/Sylius/Behat/Page/Admin/Currency/UpdatePageInterface.php

@@ -26,6 +26,11 @@ interface UpdatePageInterface extends BaseUpdatePageInterface
      */
     public function canBeDisabled();
 
+    /**
+     * @return bool
+     */
+    public function canHaveExchangeRateChanged();
+
     /**
      * @param string $exchangeRate
      */

src/Sylius/Bundle/CoreBundle/Form/Type/CurrencyType.php

@@ -55,10 +55,16 @@ class CurrencyType extends BaseCurrencyType
 
             $form = $event->getForm();
 
-            $form->add('enabled', 'checkbox', [
-                'label' => 'sylius.form.locale.enabled',
-                'disabled' => true,
-            ]);
+            $form
+                ->add('enabled', 'checkbox', [
+                    'label' => 'sylius.form.locale.enabled',
+                    'disabled' => true,
+                ])
+                ->add('exchangeRate', 'number', [
+                    'label' => 'sylius.form.currency.exchange_rate',
+                    'disabled' => true,
+                ])
+            ;
         });
     }