MAGETWO-31324: Tax labels aren't displayed for Bundle options of "multiple select" & "drop-down" types

- QA plus format fix plus test

Author: Cristian Partica

app/code/Magento/Tax/Model/Observer.php

@@ -320,7 +320,7 @@ public function updateProductOptions(\Magento\Framework\Event\Observer $observer
             $options['optionTemplate'] = sprintf(
                 '<%%= data.label %%>'
                 . '<%% if (data.basePrice.value) { %%>'
-                . ' <%%= data.basePrice.formatted %%>'
+                . ' +<%%= data.basePrice.formatted %%>'
                 . '<%% } %%>'
             );
         }

app/code/Magento/Tax/Test/Unit/Model/ObserverTest.php

@@ -91,7 +91,7 @@ public function dataProviderUpdateProductOptions()
                 'expected' => [
                     'calculationAlgorithm' => 'TOTAL_BASE_CALCULATION',
                     'optionTemplate' => '<%= data.label %><% if (data.finalPrice.value) '.
-                        '{ %> <%= data.finalPrice.formatted %> (Excl. tax: <%= data.basePrice.formatted %>)<% } %>',
+                        '{ %> +<%= data.finalPrice.formatted %> (Excl. tax: <%= data.basePrice.formatted %>)<% } %>',
                 ],
                 'displayBothPrices' => true,
                 'priceIncludesTax' => false,
@@ -101,7 +101,7 @@ public function dataProviderUpdateProductOptions()
                 'expected' => [
                     'calculationAlgorithm' => 'TOTAL_BASE_CALCULATION',
                     'optionTemplate' => '<%= data.label %><% if (data.basePrice.value) '.
-                        '{ %> <%= data.basePrice.formatted %><% } %>',
+                        '{ %> +<%= data.basePrice.formatted %><% } %>',
                 ],
                 'displayBothPrices' => false,
                 'priceIncludesTax' => true,