Merge pull request #2107 from znz/add-to_yaml

Add Object#to_yaml

Author: soutaro

stdlib/psych/0/core_ext.rbs

@@ -0,0 +1,12 @@
+%a{annotate:rdoc:skip}
+class Object
+  # <!--
+  #   rdoc-file=ext/psych/lib/psych/core_ext.rb
+  #   - to_yaml(options = {})
+  # -->
+  # Convert an object to YAML.  See Psych.dump for more information on the
+  # available `options`.
+  #
+  def to_yaml: (?indentation: Integer, ?line_width: Integer, ?canonical: bool, ?header: bool) -> String
+             | [IO] (IO, ?indentation: Integer, ?line_width: Integer, ?canonical: bool, ?header: bool) -> IO
+end

test/stdlib/psych_test.rb

@@ -75,4 +75,21 @@ def test_dump
       Psych, :dump, [1], indentation: 3, line_width: 30, canonical: true, header: true
     )
   end
+
+  def test_to_yaml
+    assert_send_type(
+      "() -> ::String",
+      [1], :to_yaml
+    )
+
+    assert_send_type(
+      "(::StringIO) -> ::StringIO",
+      [1], :to_yaml, StringIO.new()
+    )
+
+    assert_send_type(
+      "(indentation: ::Integer, line_width: ::Integer, canonical: bool, header: bool) -> ::String",
+      [1], :to_yaml, indentation: 3, line_width: 30, canonical: true, header: true
+    )
+  end
 end