better handle sql queries with invalid encoding

Author: aidanharan

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 - [#1006](https://.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1006) Fix support for index types
 
+#### Changed
+
+- [#1014](https://.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1014) Better handle SQL queries with invalid encoding
+
 ## v6.1.2.1
 
 [Full changelog](https://.com/rails-sqlserver/activerecord-sqlserver-adapter/compare/v6.1.2.0...v6.1.2.1)

lib/active_record/connection_adapters/sqlserver/database_statements.rb

@@ -9,6 +9,8 @@ module DatabaseStatements
 
 def write_query?(sql) # :nodoc:
 !READ_QUERY.match?(sql)
+rescue ArgumentError # Invalid encoding
+!READ_QUERY.match?(sql.b)
 end
 
 def execute(sql, name = nil)

test/cases/coerced_tests.rb

@@ -92,6 +92,18 @@ def test_errors_when_an_insert_query_prefixed_by_a_double_dash_comment_is_called
 Subscriber.send(:load_schema!)
 original_test_errors_when_an_insert_query_prefixed_by_a_double_dash_comment_is_called_while_preventing_writes
 end
+
+coerce_tests! :test_doesnt_error_when_a_select_query_has_encoding_errors
+def test_doesnt_error_when_a_select_query_has_encoding_errors_coerced
+ActiveRecord::Base.while_preventing_writes do
+# TinyTDS fail on encoding errors.
+# But at least we can assert it fails in the client and not before when trying to
+# match the query.
+assert_raises ActiveRecord::StatementInvalid do
+@connection.select_all("SELECT '\xC8'")
+end
+end
+end
 end
 end