From 913c20486c33344a27df54ace1ab1f23813c6672 Mon Sep 17 00:00:00 2001
From: Nathan Glass <nagl@stripe.com>
Date: Wed, 15 Dec 2021 18:21:04 -0800
Subject: [PATCH 1/2] Make error deserialization more resilient

---
 lib/temporal/workflow/errors.rb               |  3 +-
 .../unit/lib/temporal/workflow/errors_spec.rb | 38 ++++++++++++++++++-
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/lib/temporal/workflow/errors.rb b/lib/temporal/workflow/errors.rb
index d7c294f5..cea7f471 100644
--- a/lib/temporal/workflow/errors.rb
+++ b/lib/temporal/workflow/errors.rb
@@ -25,7 +25,7 @@ def self.generate_error(failure, default_exception_class = StandardError)
 
           begin
             exception = exception_class.new(message)
-          rescue ArgumentError => deserialization_error
+          rescue => deserialization_error
             # We don't currently support serializing/deserializing exceptions with more than one argument.
             message = "#{exception_class}: #{message}"
             exception = default_exception_class.new(message)
@@ -33,6 +33,7 @@ def self.generate_error(failure, default_exception_class = StandardError)
               "Could not instantiate original error. Defaulting to StandardError.", 
               {
                 original_error: failure.application_failure_info.type,
+                instantiation_error_class: deserialization_error.class.to_s,
                 instantiation_error_message: deserialization_error.message,
               },
             ) 
diff --git a/spec/unit/lib/temporal/workflow/errors_spec.rb b/spec/unit/lib/temporal/workflow/errors_spec.rb
index a9e053f6..13937473 100644
--- a/spec/unit/lib/temporal/workflow/errors_spec.rb
+++ b/spec/unit/lib/temporal/workflow/errors_spec.rb
@@ -4,6 +4,14 @@ class ErrorWithTwoArgs < StandardError
   def initialize(message, another_argument); end
 end
 
+class ErrorThatRaisesInInitialize < StandardError
+  def initialize(message)
+    # This class simulates an error class that has bugs in its initialize method, or where
+    # the arg isn't a string. It raises TypeError (String can't be coerced into Integer)
+    1 + message
+  end
+end
+
 class SomeError < StandardError; end
 
 describe Temporal::Workflow::Errors do
@@ -51,7 +59,7 @@ class SomeError < StandardError; end
     end
 
 
-    it "falls back to StandardError when the client can't initialize the error class" do 
+    it "falls back to StandardError when the client can't initialize the error class due to arity" do 
       allow(Temporal.logger).to receive(:error)
 
       message = "An error message"
@@ -73,10 +81,38 @@ class SomeError < StandardError; end
           'Could not instantiate original error. Defaulting to StandardError.',
           {
             original_error: "ErrorWithTwoArgs",
+            instantiation_error_class: "ArgumentError",
             instantiation_error_message: "wrong number of arguments (given 1, expected 2)",
           },
         )
     end
 
+    it "falls back to StandardError when the client can't initialize the error class when initialize doesn't take a string" do 
+      allow(Temporal.logger).to receive(:error)
+
+      message = "An error message"
+      stack_trace = ["a fake backtrace"]
+      failure = Fabricate(
+        :api_application_failure,
+        message: message,
+        backtrace: stack_trace,
+        error_class: ErrorThatRaisesInInitialize.to_s,
+      )
+
+      e = Temporal::Workflow::Errors.generate_error(failure)
+      expect(e).to be_a(StandardError)
+      expect(e.message).to eq("ErrorThatRaisesInInitialize: An error message")
+      expect(e.backtrace).to eq(stack_trace)
+      expect(Temporal.logger)
+        .to have_received(:error)
+        .with(
+          'Could not instantiate original error. Defaulting to StandardError.',
+          {
+            original_error: "ErrorThatRaisesInInitialize",
+            instantiation_error_class: "TypeError",
+            instantiation_error_message: "String can't be coerced into Integer",
+          },
+        )
+    end
   end
 end

From 0dbd46634dd0871d4da568d5456ef26a5af07afc Mon Sep 17 00:00:00 2001
From: Nathan Glass <nagl@stripe.com>
Date: Wed, 5 Jan 2022 10:17:37 -0800
Subject: [PATCH 2/2] Raise TypeError directly in the test

---
 spec/unit/lib/temporal/workflow/errors_spec.rb | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/spec/unit/lib/temporal/workflow/errors_spec.rb b/spec/unit/lib/temporal/workflow/errors_spec.rb
index 13937473..05d5f82a 100644
--- a/spec/unit/lib/temporal/workflow/errors_spec.rb
+++ b/spec/unit/lib/temporal/workflow/errors_spec.rb
@@ -7,8 +7,9 @@ def initialize(message, another_argument); end
 class ErrorThatRaisesInInitialize < StandardError
   def initialize(message)
     # This class simulates an error class that has bugs in its initialize method, or where
-    # the arg isn't a string. It raises TypeError (String can't be coerced into Integer)
-    1 + message
+    # the arg isn't a string. It raises the sort of TypeError that would happen if you wrote
+    # 1 + message
+    raise TypeError.new("String can't be coerced into Integer")
   end
 end