ENGCOM-6028: #981 Extend test coverage for BraintreeGraphQl #983

 - Merge Pull Request magento/graphql-ce#983 from TomashKhamlai/graphql-ce:issue/981
 - Merged commits:
   1. 287e906

dev/tests/api-functional/testsuite/Magento/GraphQl/Braintree/CreateBraintreeClientTokenTest.php

@@ -20,6 +20,7 @@ class CreateBraintreeClientTokenTest extends GraphQlAbstract
      * @magentoConfigFixture default_store payment/braintree/active 1
      * @magentoConfigFixture default_store payment/braintree/environment sandbox
      * @magentoConfigFixture default_store payment/braintree/merchant_id def_merchant_id
+     * @magentoConfigFixture default_store payment/braintree/merchant_account_id def_merchant_id
      * @magentoConfigFixture default_store payment/braintree/public_key def_public_key
      * @magentoConfigFixture default_store payment/braintree/private_key def_private_key
      */

dev/tests/api-functional/testsuite/Magento/GraphQl/Braintree/Customer/SetPaymentMethodTest.php

@@ -8,6 +8,7 @@
 namespace Magento\GraphQl\Braintree\Customer;
 
 use Magento\Braintree\Gateway\Command\GetPaymentNonceCommand;
+use Magento\Framework\Exception\AuthenticationException;
 use Magento\Framework\Registry;
 use Magento\GraphQl\Quote\GetMaskedQuoteIdByReservedOrderId;
 use Magento\Integration\Api\CustomerTokenServiceInterface;
@@ -261,6 +262,34 @@ public function testSetPaymentMethodInvalidMethodInput(string $methodCode)
         $this->graphQlMutation($setPaymentQuery, [], '', $this->getHeaderMap());
     }
 
+    /**
+     * @magentoConfigFixture default_store carriers/flatrate/active 1
+     * @magentoConfigFixture default_store payment/braintree/active 1
+     * @magentoConfigFixture default_store payment/braintree_cc_vault/active 1
+     * @magentoConfigFixture default_store payment/braintree/environment sandbox
+     * @magentoConfigFixture default_store payment/braintree/merchant_id def_merchant_id
+     * @magentoConfigFixture default_store payment/braintree/public_key def_public_key
+     * @magentoConfigFixture default_store payment/braintree/private_key def_private_key
+     * @magentoApiDataFixture Magento/Customer/_files/customer.php
+     * @magentoApiDataFixture Magento/GraphQl/Catalog/_files/simple_product.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/customer/create_empty_cart.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/add_simple_product.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/set_new_shipping_address.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/set_new_billing_address.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/set_flatrate_shipping_method.php
+     * @dataProvider dataProviderTestSetPaymentMethodInvalidInput
+     * @expectedException \Exception
+     */
+    public function testSetPaymentMethodWithoutRequiredPaymentMethodInput()
+    {
+        $reservedOrderId = 'test_quote';
+        $maskedQuoteId = $this->getMaskedQuoteIdByReservedOrderId->execute($reservedOrderId);
+
+        $setPaymentQuery = $this->getSetPaymentBraintreeQueryInvalidPaymentMethodInput($maskedQuoteId);
+        $this->expectExceptionMessage("for \"braintree\" is missing.");
+        $this->graphQlMutation($setPaymentQuery, [], '', $this->getHeaderMap());
+    }
+
     public function dataProviderTestSetPaymentMethodInvalidInput(): array
     {
         return [
@@ -371,6 +400,33 @@ private function getSetPaymentBraintreeQueryInvalidInput(string $maskedQuoteId,
 QUERY;
     }
 
+    /**
+     * @param string $maskedQuoteId
+     * @return string
+     */
+    private function getSetPaymentBraintreeQueryInvalidPaymentMethodInput(string $maskedQuoteId): string
+    {
+        return <<<QUERY
+mutation {
+  setPaymentMethodOnCart(input:{
+    cart_id:"{$maskedQuoteId}"
+    payment_method:{
+      code:"braintree"
+      braintree:{
+        payment_method_nonce:"fake-valid-nonce"
+      }
+    }
+  }) {
+    cart {
+      selected_payment_method {
+        code
+      }
+    }
+  }
+}
+QUERY;
+    }
+
     /**
      * @param string $maskedQuoteId
      * @param string $methodCode
@@ -437,7 +493,7 @@ private function getPaymentTokenQuery(): string
      * @param string $username
      * @param string $password
      * @return array
-     * @throws \Magento\Framework\Exception\AuthenticationException
+     * @throws AuthenticationException
      */
     private function getHeaderMap(string $username = '[email protected]', string $password = 'password'): array
     {