Add $remove to YamlLoader

lib/test/test_yaml_loader.rb

@@ -7,6 +7,50 @@
 
 class TestYamlLoader < Minitest::Test
 
+
+  def test_remove
+    yaml = <<~YAML
+      base:
+        key1: value1
+        key2: value2
+
+      child:
+        $mref: "#/base"
+        $remove: key2
+        key3: value3
+    YAML
+
+    f = Tempfile.new("yml")
+    f.write(yaml)
+    f.flush
+
+    doc = YamlLoader.load(f.path)
+    assert_equal({ "key1" => "value1", "key3" => "value3" }, doc["child"])
+  end
+
+  def test_multiple_remove
+    yaml = <<~YAML
+      base:
+        key1: value1
+        key2: value2
+        key3: value3
+
+      child:
+        $mref: "#/base"
+        $remove:
+        - key2
+        - key3
+        key4: value4
+    YAML
+
+    f = Tempfile.new("yml")
+    f.write(yaml)
+    f.flush
+
+    doc = YamlLoader.load(f.path)
+    assert_equal({ "key1" => "value1", "key4" => "value4" }, doc["child"])
+  end
+
   def test_that_mref_with_nested_replace_works
     yaml = <<~YAML
       base:

lib/yaml_loader.rb

@@ -14,6 +14,7 @@ def self.expand(filename, obj, yaml_opts = {})
 
     return obj.map { |v| expand(filename, v, yaml_opts) } if obj.is_a?(Array)
 
+    new_obj =
     if obj.keys.include?("$ref")
       # according JSON Reference, all keys except $ref are ignored
       relative_path = obj["$ref"].split("#")[0]
@@ -103,7 +104,9 @@ def self.expand(filename, obj, yaml_opts = {})
           end
         end
       end
+
       final_obj
+
     else
       obj_keys = obj.keys
       obj_keys.each do |key|
@@ -113,6 +116,16 @@ def self.expand(filename, obj, yaml_opts = {})
       end
       obj
     end
+
+    obj_keys = new_obj.keys
+    if obj_keys.include? "$remove"
+      remove_keys = obj["$remove"].is_a?(Array) ? obj["$remove"] : [obj["$remove"]]
+      remove_keys.each do |key|
+        new_obj.delete(key)
+      end
+    end
+    new_obj.delete("$remove")
+    new_obj
   end
 
   # load a YAML file and expand any $ref/$mref references