Replace non UTF-8 characters before JSON encoding

lib/castle.rb

@@ -18,6 +18,7 @@
 require 'castle/failover_auth_response'
 require 'castle/client'
 require 'castle/header_formatter'
+require 'castle/replace_invalid_characters'
 require 'castle/secure_mode'
 require 'castle/extractors/client_id'
 require 'castle/extractors/headers'

lib/castle/replace_invalid_characters.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module Castle
+  class ReplaceInvalidCharacters
+    def self.call(hash)
+      return hash unless hash.is_a?(Hash)
+      hash.each_with_object({}) do |(k, v), h|
+        h[k] = if v.is_a?(Hash)
+                 call(v)
+               elsif v.is_a?(String)
+                 v.encode('UTF-8', invalid: :replace, undef: :replace)
+               else
+                 v
+               end
+      end
+    end
+  end
+end

lib/castle/request.rb

@@ -20,7 +20,7 @@ def build(endpoint, args, method)
       request = Net::HTTP.const_get(method.to_s.capitalize).new(
         "#{@config.api_endpoint.path}/#{endpoint}", @headers
       )
-      request.body = args.to_json
+      request.body = ::Castle::ReplaceInvalidCharacters.call(args).to_json
       add_basic_auth(request)
       request
     end

spec/lib/castle/replace_invalid_characters_spec.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Castle::ReplaceInvalidCharacters do
+  subject { described_class.call(input) }
+
+  context 'when input is a string' do
+    let(:input) { '1234' }
+
+    it { is_expected.to eq input }
+  end
+
+  context 'when input is an array' do
+    let(:input) { [1, 2, 3, '4'] }
+
+    it { is_expected.to eq input }
+  end
+
+  context 'when input is a hash' do
+    let(:input) { { user_id: 1 } }
+
+    it { is_expected.to eq input }
+  end
+
+  context 'when input is nil' do
+    let(:input) { nil }
+
+    it { is_expected.to eq input }
+  end
+
+  context 'when input is a nested hash' do
+    let(:input) { { user: { id: 1 } } }
+
+    it { is_expected.to eq input }
+  end
+
+  context 'when input is a hash with invalid UTF-8 characters' do
+    let(:input) { { user_id: "inv\xC4lid" } }
+
+    it { is_expected.to eq(user_id: 'inv�lid') }
+  end
+
+  context 'when input is a nested hash with invalid UTF-8 characters' do
+    let(:input) { { user: { id: "inv\xC4lid" } } }
+
+    it { is_expected.to eq(user: { id: 'inv�lid' }) }
+  end
+end

spec/lib/castle/request_spec.rb

@@ -32,6 +32,12 @@
       it { expect(request.path).to eql('/v1/endpoint') }
       it { expect(request.to_hash['sample-header']).to eql(['1']) }
       it { expect(request.to_hash['authorization'][0]).to match(/Basic \w/) }
+
+      context 'with non-UTF-8 charaters' do
+        let(:params) { { name: "\xC4" } }
+
+        it { expect(request.body).to eq '{"name":"�"}' }
+      end
     end
   end
 end