Fix UFC offset when deserializing iso8601 timestamp values (#3037)

Author: jterapin

gems/aws-sdk-core/CHANGELOG.md

@@ -1,6 +1,8 @@
 Unreleased Changes
 ------------------
 
+* Issue - Ensure no UTC offset when deserializing `iso8601` timestamp format values.
+
 * Feature - Bump User Agent to version 2.1 to track business metrics. This changes the User Agent plugin order to be just before sending.
 
 3.196.1 (2024-05-14)

gems/aws-sdk-core/lib/aws-sdk-core/util.rb

@@ -90,16 +90,16 @@ def deserialize_number(str)
         end
       end
 
-      # @param [String, Integer] value
+      # @param [String] value
       # @return [Time]
       def deserialize_time(value)
         case value
         when nil then nil
-        when /^\d+$/ then Time.at(value.to_i)
+        when /^[\d.]+$/ then Time.at(value.to_f).utc
         else
           begin
-            fractional_time = Time.parse(value).utc.to_f
-            Time.at(fractional_time)
+            fractional_time = Time.parse(value).to_f
+            Time.at(fractional_time).utc
           rescue ArgumentError
             raise "unhandled timestamp format `#{value}'"
           end

gems/aws-sdk-core/spec/aws/util_spec.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require_relative '../spec_helper'
+
+module Aws
+  describe Util do
+    describe '.deserialize_time' do
+      let(:time) { Time.at(946_845_296.123) }
+
+      it 'correctly parses when given value is nil' do
+        expect(Util.deserialize_time(nil)).to be_nil
+      end
+
+      it 'correctly parses when given value is a numeric string' do
+        value = time.to_f.to_s
+        expect(Util.deserialize_time(value)).to eq(time.utc)
+      end
+
+      it 'correctly parses when given value is a string' do
+        value = time.strftime '%Y-%m-%d %H:%M:%S.%N %z' # preserves frac secs
+        expect(Util.deserialize_time(value)).to eq(time.utc)
+      end
+    end
+  end
+end