1 files changed, 65 insertions, 10 deletions

diff --git a/scripts/changed-feature-flags b/scripts/changed-feature-flags
index 3a4f18bd78f..86214e86788 100755
--- a/scripts/changed-feature-flags
+++ b/scripts/changed-feature-flags
@@ -3,10 +3,12 @@
 
 require 'yaml'
 require 'optparse'
+require 'pathname'
 require_relative 'api/default_options'
 
 # This script returns the desired feature flag state as a comma-separated string for the feature flags in the specified files.
-# Each desired feature flag state is specified as 'feature-flag=state'.
+# Each desired feature flag state is specified as 'feature-flag=state'. This allows us to run package-and-qa with the
+# feature flag set to the desired state.
 #
 # For example, if the specified files included `config/feature_flags/development/ci_yaml_limit_size.yml` and the desired
 # state as specified by the second argument was enabled, the value returned would be `ci_yaml_limit_size=enabled`
@@ -15,31 +17,84 @@ class GetFeatureFlagsFromFiles
   def initialize(options)
     @files = options.delete(:files)
     @state = options.delete(:state)
+
+    abort("ERROR: Please specify the directory containing MR diffs.") if @files.to_s.empty?
   end
 
+  # Gets feature flags from definition files or diffs of deleted defition files
+  #
+  # @return [String] a comma-separated list of feature flags and their desired state
   def extracted_flags
-    files.each_with_object([]) do |file_path, all|
-      next unless file_path =~ %r{/feature_flags/(development|ops)/.*\.yml}
-      next unless File.exist?(file_path)
+    flags_list = diffs_dir.glob('**/*').each_with_object([]) do |file_path, flags|
+      ff_yaml = ff_yaml_for_file(file_path)
+      next if ff_yaml.nil?
+      break [] if ff_yaml.empty?
+
+      flags << ff_yaml['name']
+    end
+    flags_list = flags_list.map { |flag| "#{flag}=#{state}" } unless state.to_s.empty?
+    flags_list.join(',')
+  end
 
-      ff_yaml = YAML.safe_load(File.read(file_path))
-      ff_to_add = "#{ff_yaml['name']}"
-      ff_to_add += "=#{state}" unless state.to_s.empty?
+  # Loads the YAML feature flag definition based on a diff of the definition file. The definition is loaded from the
+  # definition file itself, or from a diff of the deleted definition file.
+  #
+  # @param [Pathname] path the path to the diff
+  # @return [Hash] a hash containing the YAML data for the feature flag definition
+  def ff_yaml_for_file(path)
+    return unless File.expand_path(path).to_s =~ %r{/feature_flags/(development|ops)/.*\.yml}
 
-      all << ff_to_add
-    end.join(',')
+    if path.to_s.end_with?('yml.deleted.diff')
+      # Ignore deleted feature flag definitions if we want to enable/disable existing flags.
+      return if state != 'deleted'
+
+      yaml_from_deleted_diff(path)
+    else
+      # If we want deleted definition files but find one that wasn't deleted, we return immediately to
+      # because non-deleted flags are tested in separate jobs from deleted flags, so we don't need to run
+      # a job with just deleted flags.
+      return [] if state == 'deleted'
+
+      yaml_from_file(path, diffs_dir)
+    end
   end
 
   private
 
   attr_reader :files, :state
+
+  # The absolute path to the directory of diffs
+  #
+  # @return [String]
+  def diffs_dir
+    @diffs_dir ||= Pathname.new(files).expand_path
+  end
+
+  # Loads the YAML feature flag definition from a file corresponding to a diff of the definition file.
+  #
+  # @param [Pathname] file_path the path to the diff
+  # @param [Pathname] diffs_dir the path to the diffs directory
+  # @return [Hash] a hash containing the YAML data from the feature flag definition file corresponding to the diff
+  def yaml_from_file(file_path, diffs_dir)
+    real_file_path = File.join(Dir.pwd, file_path.to_s.delete_prefix(diffs_dir.to_s)).delete_suffix('.diff')
+    YAML.safe_load(File.read(real_file_path))
+  end
+
+  # Loads the YAML feature flag definition from a diff of the deleted feature flag definition file.
+  #
+  # @param [Pathname] file_path the path of the diff
+  # @return [Hash] a hash containing the YAML data for the feature flag definition from the diff
+  def yaml_from_deleted_diff(file_path)
+    cleaned_diff = File.read(file_path).gsub(/^[^a-z]+/, '')
+    YAML.safe_load(cleaned_diff)
+  end
 end
 
 if $0 == __FILE__
   options = API::DEFAULT_OPTIONS.dup
 
   OptionParser.new do |opts|
-    opts.on("-f", "--files FILES", Array, "Comma-separated list of feature flag config files") do |value|
+    opts.on("-f", "--files FILES", String, "A directory containing diffs including feature flag definition change diffs") do |value|
       options[:files] = value
     end