Add specs for anonymous block forwarding.

Author: nirvdrum

language/block_spec.rb

@@ -983,3 +983,77 @@ def a; 1; end
     end
   end
 end
+
+describe "Anonymous block forwarding" do
+  ruby_version_is "3.1" do
+    it "forwards blocks to other functions that formally declare anonymous blocks" do
+      eval <<-EOF
+          def b(&); c(&) end
+          def c(&); yield :non_null end
+      EOF
+
+      b { |c| c }.should == :non_null
+    end
+
+    it "requires the anonymous block parameter to be declared if directly passing a block" do
+      -> { eval "def a; b(&); end; def b; end" }.should raise_error(SyntaxError)
+    end
+
+    it "works when it's the only declared parameter" do
+      eval <<-EOF
+          def inner; yield end
+          def block_only(&); inner(&) end
+      EOF
+
+      block_only { 1 }.should == 1
+    end
+
+    it "works alongside positional parameters" do
+      eval <<-EOF
+          def inner; yield end
+          def pos(arg1, &); inner(&) end
+      EOF
+
+      pos(:a) { 1 }.should == 1
+    end
+
+    it "works alongside positional arguments and splatted keyword arguments" do
+      eval <<-EOF
+          def inner; yield end
+          def pos_kwrest(arg1, **kw, &); inner(&) end
+      EOF
+
+      pos_kwrest(:a, arg: 3) { 1 }.should == 1
+    end
+
+    it "works alongside positional arguments and disallowed keyword arguments" do
+      eval <<-EOF
+          def inner; yield end
+          def no_kw(arg1, **nil, &); inner(&) end
+      EOF
+
+      no_kw(:a) { 1 }.should == 1
+    end
+  end
+
+  ruby_version_is "3.2" do
+    it "works alongside explicit keyword arguments" do
+      eval <<-EOF
+          def inner; yield end
+          def rest_kw(*a, kwarg: 1, &); inner(&) end
+          def kw(kwarg: 1, &); inner(&) end
+          def pos_kw_kwrest(arg1, kwarg: 1, **kw, &); inner(&) end
+          def pos_rkw(arg1, kwarg1:, &); inner(&) end
+          def all(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, &); inner(&) end
+          def all_kwrest(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, **kw, &); inner(&) end
+      EOF
+
+      rest_kw { 1 }.should == 1
+      kw { 1 }.should == 1
+      pos_kw_kwrest(:a) { 1 }.should == 1
+      pos_rkw(:a, kwarg1: 3) { 1 }.should == 1
+      all(:a, :b, :c, :d, :e, okw1: 'x', okw2: 'y') { 1 }.should == 1
+      all_kwrest(:a, :b, :c, :d, :e, okw1: 'x', okw2: 'y') { 1 }.should == 1
+    end
+  end
+end