ruby: introduce Gherkin::Query#parent_locations.

Cucumber::Core::Compiler will use this to tell Cucumber::Core::Test::Case the
locations of its parent lines, such as `Feature:`, `Background:`, and `Rule:`,
so that it will correctly match them during location filtering.

CHANGELOG.md

@@ -22,6 +22,7 @@ This document is formatted according to the principles of [Keep A CHANGELOG](htt
 - (i18n) Added Danish translation of "Rule"
 - (i18n) Added Dutch translation of "Rule"
 - (i18n) Added Esperanto translation of "Rule"
+- [Ruby] Added `Gherkin::Query#parent_locations` for determining a scenario's parents' line numbers ([#89](https://github.com/cucumber/gherkin/pull/89))
 
 ## [26.2.0] - 2023-04-07
 ### Changed

ruby/lib/gherkin/query.rb

@@ -2,12 +2,19 @@ module Gherkin
   class Query
     def initialize
       @ast_node_locations = {}
+      @scenario_parent_locations = {}
+      @background_locations = {}
     end
 
     def update(message)
       update_feature(message.gherkin_document.feature) if message.gherkin_document
     end
 
+    def scenario_parent_locations(scenario_node_id)
+      return @scenario_parent_locations[scenario_node_id] if @scenario_parent_locations.has_key?(scenario_node_id)
+      raise AstNodeNotLocatedException, "No scenario parent locations found for #{scenario_node_id} }. Known: #{@scenario_parent_locations.keys}"
+    end
+
     def location(ast_node_id)
       return @ast_node_locations[ast_node_id] if @ast_node_locations.has_key?(ast_node_id)
       raise AstNodeNotLocatedException, "No location found for #{ast_node_id} }. Known: #{@ast_node_locations.keys}"
@@ -20,34 +27,41 @@ def update_feature(feature)
       store_nodes_location(feature.tags)
 
       feature.children.each do |child|
-        update_rule(child.rule) if child.rule
-        update_background(child.background) if child.background
-        update_scenario(child.scenario) if child.scenario
+        update_rule(feature, child.rule) if child.rule
+        update_background(feature, child.background) if child.background
+        update_scenario(feature, child.rule, child.scenario) if child.scenario
       end
     end
 
-    def update_rule(rule)
+    def update_rule(feature, rule)
       return if rule.nil?
       store_nodes_location(rule.tags)
-
       rule.children.each do |child|
-        update_background(child.background) if child.background
-        update_scenario(child.scenario) if child.scenario
+        update_background(rule, child.background) if child.background
+        update_scenario(feature, rule, child.scenario) if child.scenario
       end
     end
 
-    def update_background(background)
+    def update_background(parent, background)
       update_steps(background.steps)
+      @background_locations[parent] = background.location
     end
 
-    def update_scenario(scenario)
+    def update_scenario(feature, rule, scenario)
       store_node_location(scenario)
       store_nodes_location(scenario.tags)
       update_steps(scenario.steps)
       scenario.examples.each do |examples|
         store_nodes_location(examples.tags || [])
         store_nodes_location(examples.table_body || [])
       end
+
+      @scenario_parent_locations[scenario.id] = [
+        feature.location,
+        @background_locations[feature],
+        rule&.location,
+        @background_locations[rule],
+      ].compact
     end
 
     def update_steps(steps)

ruby/spec/gherkin/query_spec.rb

@@ -47,6 +47,7 @@ def find_message_by_attribute(messages, attribute)
         Examples:
           | Status |
           | passed |
+          | failed |
 
       @rule-tag
       Rule: this is a rule
@@ -71,6 +72,56 @@ def find_message_by_attribute(messages, attribute)
     end
   end
 
+  describe '#scenario_parent_locations' do
+    before do
+      messages.each { |message| subject.update(message) }
+    end
+
+    let(:background) { find_message_by_attribute(gherkin_document.feature.children, :background) }
+    let(:scenarios) { filter_messages_by_attribute(gherkin_document.feature.children, :scenario) }
+
+    context 'without rule' do
+      let(:scenario) { scenarios.first }
+
+      it 'provides the feature and background locations of a given scenario node id' do
+        expect(subject.scenario_parent_locations(scenario.id)).to eq([
+          gherkin_document.feature.location,
+          background.location,
+        ])
+      end
+    end
+
+    context 'with rule' do
+      let(:rule) { find_message_by_attribute(gherkin_document.feature.children, :rule) }
+      let(:rule_background) { find_message_by_attribute(rule.children, :background) }
+      let(:scenario) { find_message_by_attribute(rule.children, :scenario) }
+
+      it 'provides the feature, background, rule, and rule background locations of a given scenario node id' do
+        expect(subject.scenario_parent_locations(scenario.id)).to eq([
+          gherkin_document.feature.location,
+          background.location,
+          rule.location,
+          rule_background.location,
+        ])
+      end
+    end
+
+    context 'in a scenario outline' do
+      let(:scenario) { scenarios.last }
+
+      it 'provides the feature and background locations of a given scenario outline node id' do
+        expect(subject.scenario_parent_locations(scenario.id)).to eq([
+          gherkin_document.feature.location,
+          background.location,
+        ])
+      end
+    end
+
+    it 'raises an exception if called with an invalid id' do
+      expect { subject.scenario_parent_locations("BAD") }.to raise_error(Gherkin::AstNodeNotLocatedException)
+    end
+  end
+
   describe '#location' do
     before do
       messages.each { |message| subject.update(message) }