Fix initialize return type when sig uses .void.checked(:tests)

lib/tapioca/gem/listeners/sorbet_signatures.rb

@@ -16,7 +16,12 @@ def on_method(event)
           signature = event.signature
           return unless signature
 
-          event.node.sigs << compile_signature(signature, event.parameters)
+          sig = compile_signature(signature, event.parameters)
+          # `initialize` must always return void. When a sig uses `.void.checked(:tests)`,
+          # Sorbet introspects the return type as `T.anything` outside of test mode, so we
+          # correct it here.
+          sig.return_type = "void" if event.node.name == "initialize"
+          event.node.sigs << sig
         end
 
         #: (untyped signature, Array[[Symbol, String]] parameters) -> RBI::Sig

spec/tapioca/gem/pipeline_spec.rb

@@ -2225,6 +2225,28 @@ def initialize; end
       assert_equal(output, compile)
     end
 
+    it "compiles initialize with void sig using checked(:tests)" do
+      add_ruby_file("bar.rb", <<~RUBY)
+        class Bar
+          extend T::Sig
+
+          sig { params(x: Integer).void.checked(:tests) }
+          def initialize(x)
+            @x = x
+          end
+        end
+      RUBY
+
+      output = template(<<~RBI)
+        class Bar
+          sig { params(x: ::Integer).void }
+          def initialize(x); end
+        end
+      RBI
+
+      assert_equal(output, compile)
+    end
+
     it "understands redefined attr_accessor" do
       add_ruby_file("toto.rb", <<~RUBY)
         class Toto