1 files changed, 64 insertions, 0 deletions
diff --git a/spec/ruby/core/proc/ruby2_keywords_spec.rb b/spec/ruby/core/proc/ruby2_keywords_spec.rb
new file mode 100644
index 0000000000..4f6bc151b6
--- /dev/null
+++ b/spec/ruby/core/proc/ruby2_keywords_spec.rb
@@ -0,0 +1,64 @@
+require_relative '../../spec_helper'
+
+ruby_version_is "2.7" do
+  describe "Proc#ruby2_keywords" do
+    it "marks the final hash argument as keyword hash" do
+      f = -> *a { a.last }
+      f.ruby2_keywords
+
+      last = f.call(1, 2, a: "a")
+      Hash.ruby2_keywords_hash?(last).should == true
+    end
+
+    ruby_version_is "2.7" ... "3.0" do
+      it "fixes delegation warnings when calling a method accepting keywords" do
+        obj = Object.new
+        def obj.foo(*a, **b) end
+
+        f = -> *a { obj.foo(*a) }
+
+        -> { f.call(1, 2, {a: "a"}) }.should complain(/Using the last argument as keyword parameters is deprecated/)
+        f.ruby2_keywords
+        -> { f.call(1, 2, {a: "a"}) }.should_not complain
+      end
+
+      it "fixes delegation warnings when calling a proc accepting keywords" do
+        g = -> *a, **b { }
+        f = -> *a { g.call(*a) }
+
+        -> { f.call(1, 2, {a: "a"}) }.should complain(/Using the last argument as keyword parameters is deprecated/)
+        f.ruby2_keywords
+        -> { f.call(1, 2, {a: "a"}) }.should_not complain
+      end
+    end
+
+    it "returns self" do
+      f = -> *a { }
+      f.ruby2_keywords.should equal f
+    end
+
+    it "prints warning when a proc does not accept argument splat" do
+      f = -> a, b, c { }
+
+      -> {
+        f.ruby2_keywords
+      }.should complain(/Skipping set of ruby2_keywords flag for/)
+    end
+
+    it "prints warning when a proc accepts keywords" do
+      f = -> a:, b: { }
+
+      -> {
+        f.ruby2_keywords
+      }.should complain(/Skipping set of ruby2_keywords flag for/)
+    end
+
+    it "prints warning when a proc accepts keyword splat" do
+      f = -> **a { }
+
+      -> {
+        f.ruby2_keywords
+      }.should complain(/Skipping set of ruby2_keywords flag for/)
+    end
+  end
+end