magento/graphql-ce#727: currentPage: 0, currentPage: 1 and currentPage: -1 produces the same output for products query when filtering is used

- added currentPage and pageSize validation;
- fixed broken pagination;
- fixed benchmark.jms that relied on wrong query params.

Author: lenaorobei

app/code/Magento/CatalogGraphQl/Model/Resolver/Category/Products.php

@@ -66,6 +66,12 @@ public function resolve(
             ]
         ];
         $searchCriteria = $this->searchCriteriaBuilder->build($field->getName(), $args);
+        if ($args['currentPage'] < 1) {
+            throw new GraphQlInputException(__('currentPage value must be greater than 0.'));
+        }
+        if ($args['pageSize'] < 1) {
+            throw new GraphQlInputException(__('pageSize value must be greater than 0.'));
+        }
         $searchCriteria->setCurrentPage($args['currentPage']);
         $searchCriteria->setPageSize($args['pageSize']);
         $searchResult = $this->filterQuery->getResult($searchCriteria, $info);

app/code/Magento/CatalogGraphQl/Model/Resolver/Products.php

@@ -71,6 +71,12 @@ public function resolve(
         array $args = null
     ) {
         $searchCriteria = $this->searchCriteriaBuilder->build($field->getName(), $args);
+        if ($args['currentPage'] < 1) {
+            throw new GraphQlInputException(__('currentPage value must be greater than 0.'));
+        }
+        if ($args['pageSize'] < 1) {
+            throw new GraphQlInputException(__('pageSize value must be greater than 0.'));
+        }
         $searchCriteria->setCurrentPage($args['currentPage']);
         $searchCriteria->setPageSize($args['pageSize']);
         if (!isset($args['search']) && !isset($args['filter'])) {

app/code/Magento/CatalogGraphQl/Model/Resolver/Products/Query/Search.php

@@ -144,7 +144,7 @@ private function paginateList(SearchResult $searchResult, SearchCriteriaInterfac
         $offset = $length * ($searchCriteria->getCurrentPage() - 1);
 
         if ($searchCriteria->getPageSize()) {
-            $maxPages = ceil($searchResult->getTotalCount() / $searchCriteria->getPageSize()) - 1;
+            $maxPages = ceil($searchResult->getTotalCount() / $searchCriteria->getPageSize());
         } else {
             $maxPages = 0;
         }

dev/tests/api-functional/testsuite/Magento/GraphQl/Catalog/ProductSearchTest.php

@@ -1137,6 +1137,64 @@ public function testFilterProductsThatAreOutOfStockWithConfigSettings()
         $this->assertEquals(1, $response['products']['total_count']);
     }
 
+    /**
+     * Verify that invalid current page return an error
+     *
+     * @magentoApiDataFixture Magento/Catalog/_files/products_with_layered_navigation_attribute.php
+     * @expectedException \Exception
+     * @expectedExceptionMessage currentPage value must be greater than 0
+     */
+    public function testInvalidCurrentPage()
+    {
+        $query = <<<QUERY
+{
+  products (
+    filter: {
+      sku: {
+        like:"simple%"
+      }
+    }
+    pageSize: 4
+    currentPage: 0
+  ) {
+    items {
+      sku
+    }
+  }
+}
+QUERY;
+        $this->graphQlQuery($query);
+    }
+
+    /**
+     * Verify that invalid page size returns an error.
+     *
+     * @magentoApiDataFixture Magento/Catalog/_files/products_with_layered_navigation_attribute.php
+     * @expectedException \Exception
+     * @expectedExceptionMessage pageSize value must be greater than 0
+     */
+    public function testInvalidPageSize()
+    {
+        $query = <<<QUERY
+{
+  products (
+    filter: {
+      sku: {
+        like:"simple%"
+      }
+    }
+    pageSize: 0
+    currentPage: 1
+  ) {
+    items {
+      sku
+    }
+  }
+}
+QUERY;
+        $this->graphQlQuery($query);
+    }
+
     /**
      * Asserts the different fields of items returned after search query is executed
      *