fixing the ancestor-chain, adding tests on removed children

app/controllers/api/v2/planning_elements_controller.rb

@@ -261,7 +261,7 @@ module Api
           # remove all children, that are not present in the filtered set
           pe.children = pe.children.select {|child| filtered_ids.include? child.id} unless pe.children.empty?
           # re-wire the parent of this pe to the first ancestor found in the filtered set
-          pe.parent = pe.ancestors.select {|ancestor| filtered_ids.include? ancestor.id}.first if pe.parent_id
+          pe.parent = pe.ancestors.select {|ancestor| filtered_ids.include? ancestor.id}.last if pe.parent_id
         end
       end
     end

features/planning_elements/filter.feature

@@ -144,6 +144,18 @@ Feature: Filtering work packages via the api
     And the json-response should contain a work_package "work_package#1.1.1"
     And the json-response should say that "work_package#1" is parent of "work_package#1.1.1"
 
+  Scenario: The parent should be rewired to the first ancestor present in the filtered set
+    Given there are the following work packages in project "sample_project":
+      | subject              | type       | parent             |
+      | work_package#1       | Epic       |                    |
+      | work_package#1.1     | Task       | work_package#1     |
+      | work_package#1.1.1   | Bug        | work_package#1.1   |
+      | work_package#1.1.1.1 | Task       | work_package#1.1.1 |
+
+    When I call the work_package-api on project "sample_project" requesting format "json" filtering for type "Epic,Task"
+    Then the json-response should include 3 work packages
+    And the json-response should say that "work_package#1.1" is parent of "work_package#1.1.1.1"
+
   Scenario: When all ancestors are filtered, the work_package should have no parent
     Given there are the following work packages in project "sample_project":
       | subject            | type       | parent           |
@@ -154,3 +166,11 @@ Feature: Filtering work packages via the api
     Then the json-response should include 1 work packages
     And the json-response should say that "work_package#1.1.1" has no parent
 
+  Scenario: Children are filtered out
+    Given there are the following work packages in project "sample_project":
+      | subject            | type       | parent           |
+      | work_package#1     | Epic       |                  |
+      | work_package#1.1   | Task       | work_package#1   |
+      | work_package#1.2   | Story      | work_package#1   |
+    When I call the work_package-api on project "sample_project" requesting format "json" filtering for type "Epic,Story"
+    And the json-response should say that "work_package#1" has 1 child

features/step_definitions/api_steps.rb

@@ -62,6 +62,11 @@ And(/^the json\-response should say that "(.*?)" has no parent$/) do |child_name
   expect(child["parent"]).to be_nil
 end
 
+And(/^the json\-response should say that "(.*?)" has (\d+) child(ren)?$/) do |parent_name, nr_of_children,plural|
+  parent = decoded_json["planning_elements"].select {|wp| wp["name"] == parent_name}.first
+  expect(parent["children"].size).to eql nr_of_children.to_i
+end
+
 
 Then(/^I call the work_package\-api on project "(.*?)" requesting format "(.*?)" filtering for type "(.*?)"$/) do |project_name, format, type_names|
   types = Project.find_by_identifier(project_name).types.where(name: type_names.split(","))