[rubygems/rubygems] Handle empty array

https://github.com/rubygems/rubygems/commit/7c0afdd9af

lib/bundler/yaml_serializer.rb

@@ -17,7 +17,11 @@ module Bundler
         if v.is_a?(Hash)
           yaml << dump_hash(v).gsub(/^(?!$)/, "  ") # indent all non-empty lines
         elsif v.is_a?(Array) # Expected to be array of strings
-          yaml << "\n- " << v.map {|s| s.to_s.gsub(/\s+/, " ").inspect }.join("\n- ") << "\n"
+          if v.empty?
+            yaml << " []\n"
+          else
+            yaml << "\n- " << v.map {|s| s.to_s.gsub(/\s+/, " ").inspect }.join("\n- ") << "\n"
+          end
         else
           yaml << " " << v.to_s.gsub(/\s+/, " ").inspect << "\n"
         end
@@ -63,6 +67,7 @@ module Bundler
             last_empty_key = key
             last_hash = stack[depth]
           else
+            val = [] if val == "[]" # empty array
             stack[depth][key] = val
           end
         elsif match = ARRAY_REGEX.match(line)

lib/rubygems/yaml_serializer.rb

@@ -17,7 +17,11 @@ module Gem
         if v.is_a?(Hash)
           yaml << dump_hash(v).gsub(/^(?!$)/, "  ") # indent all non-empty lines
         elsif v.is_a?(Array) # Expected to be array of strings
-          yaml << "\n- " << v.map {|s| s.to_s.gsub(/\s+/, " ").inspect }.join("\n- ") << "\n"
+          if v.empty?
+            yaml << " []\n"
+          else
+            yaml << "\n- " << v.map {|s| s.to_s.gsub(/\s+/, " ").inspect }.join("\n- ") << "\n"
+          end
         else
           yaml << " " << v.to_s.gsub(/\s+/, " ").inspect << "\n"
         end
@@ -63,6 +67,7 @@ module Gem
             last_empty_key = key
             last_hash = stack[depth]
           else
+            val = [] if val == "[]" # empty array
             stack[depth][key] = val
           end
         elsif match = ARRAY_REGEX.match(line)

spec/bundler/bundler/yaml_serializer_spec.rb

@@ -57,6 +57,19 @@ RSpec.describe Bundler::YAMLSerializer do
 
       expect(serializer.dump(hash)).to eq(expected)
     end
+
+    it "handles empty array" do
+      hash = {
+        "empty_array" => [],
+      }
+
+      expected = <<~YAML
+        ---
+        empty_array: []
+      YAML
+
+      expect(serializer.dump(hash)).to eq(expected)
+    end
   end
 
   describe "#load" do
@@ -148,6 +161,19 @@ RSpec.describe Bundler::YAMLSerializer do
 
       expect(serializer.load(yaml)).to eq(hash)
     end
+
+    it "handles empty array" do
+      yaml = <<~YAML
+        ---
+        empty_array: []
+      YAML
+
+      hash = {
+        "empty_array" => [],
+      }
+
+      expect(serializer.load(yaml)).to eq(hash)
+    end
   end
 
   describe "against yaml lib" do