From d0ff758488c8337b9017ceb8a80c2c04b3efe2f8 Mon Sep 17 00:00:00 2001
From: Brian Malinconico <bmalinconico@terminus.com>
Date: Thu, 1 Sep 2022 14:51:23 -0400
Subject: [PATCH] Adding call through to existing defiend handler

---
 lib/rspec/sorbet/doubles.rb   | 13 +++++++++++--
 spec/lib/rspec/sorbet_spec.rb | 27 +++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/lib/rspec/sorbet/doubles.rb b/lib/rspec/sorbet/doubles.rb
index e412736..18c81c3 100644
--- a/lib/rspec/sorbet/doubles.rb
+++ b/lib/rspec/sorbet/doubles.rb
@@ -11,6 +11,8 @@ def allow_doubles!
           inline_type_error_handler(error)
         end
 
+        @existing_handler = T::Configuration.instance_variable_get(:@call_validation_error_handler)
+
         T::Configuration.call_validation_error_handler = proc do |signature, opts|
           call_validation_error_handler(signature, opts)
         end
@@ -23,6 +25,13 @@ def allow_doubles!
       INLINE_DOUBLE_REGEX =
         /T.(?:let|cast): Expected type (?:T.(?<t_method>any|nilable|class_of)\()?(?<expected_types>[a-zA-Z0-9:: ,]*)(\))?, got (?:type .* with value )?#<(?<double_type>Instance|Class|Object)?Double([\(]|[ ])(?<doubled_type>[a-zA-Z0-9:: ,]*)(\))?/.freeze
 
+
+      def handle_call_validation_error(signature, opts)
+        raise TypeError, opts[:pretty_message] unless @existing_handler 
+
+        @existing_handler.call(signature, opts)
+      end
+
       def inline_type_error_handler(error)
         case error
         when TypeError
@@ -75,7 +84,7 @@ def typed_array_message?(message)
         message.match?(TYPED_ARRAY_MESSAGE)
       end
 
-      def call_validation_error_handler(_signature, opts)
+      def call_validation_error_handler(signature, opts)
         should_raise = true
 
         message = opts.fetch(:pretty_message, opts.fetch(:message, ''))
@@ -108,7 +117,7 @@ def call_validation_error_handler(_signature, opts)
           end
         end
 
-        raise TypeError, opts[:pretty_message] if should_raise
+        handle_call_validation_error(signature, opts) if should_raise
       end
     end
   end
diff --git a/spec/lib/rspec/sorbet_spec.rb b/spec/lib/rspec/sorbet_spec.rb
index eef5c4e..93ec4e0 100644
--- a/spec/lib/rspec/sorbet_spec.rb
+++ b/spec/lib/rspec/sorbet_spec.rb
@@ -131,6 +131,33 @@ class Animal; end
         it_should_behave_like 'it allows an instance double'
       end
 
+      describe 'with an existing error handler' do
+        let(:handler) { proc {|_,_| } }
+
+        before do
+          T::Configuration.call_validation_error_handler  = handler
+          described_class.allow_doubles!
+        end
+
+
+        class PassthroughSig
+          extend T::Sig
+
+          sig { params(message: String).void }
+          def initialize(message)
+            @message = message
+          end
+        end
+
+        specify do
+          expect(handler).to receive(:call)
+         
+          # Error is not rasied becasue handler is no-op
+          expect { PassthroughSig.new(123) }.not_to raise_error
+        end
+
+      end
+
       describe 'class doubles' do
         extend T::Sig