Only fetch needed Plaid products, improve Plaid tests and mocks

app/models/plaid_item/accounts_snapshot.rb

@@ -62,18 +62,32 @@ class PlaidItem::AccountsSnapshot
       )
     end
 
+    def can_fetch_transactions?
+      plaid_item.supports_product?("transactions") && accounts.any?
+    end
+
     def transactions_data
-      return nil unless plaid_item.supports_product?("transactions")
+      return nil unless can_fetch_transactions?
       @transactions_data ||= plaid_provider.get_transactions(plaid_item.access_token)
     end
 
+    def can_fetch_investments?
+      plaid_item.supports_product?("investments") &&
+      accounts.any? { |a| a.type == "investment" }
+    end
+
     def investments_data
-      return nil unless plaid_item.supports_product?("investments")
+      return nil unless can_fetch_investments?
       @investments_data ||= plaid_provider.get_item_investments(plaid_item.access_token)
     end
 
+    def can_fetch_liabilities?
+      plaid_item.supports_product?("liabilities") &&
+      accounts.any? { |a| [ "credit", "loan" ].include?(a.type) }
+    end
+
     def liabilities_data
-      return nil unless plaid_item.supports_product?("liabilities")
+      return nil unless can_fetch_liabilities?
       @liabilities_data ||= plaid_provider.get_item_liabilities(plaid_item.access_token)
     end
 end