[ruby/csv] parser: fix a keep bug that some texts may be dropped unexpectedly

Ruby: [Bug #18245] [ruby-core:105587]

Reported by Hassan Abdul Rehman.

https://github.com/ruby/csv/commit/5c6523da0a

1 files changed, 37 insertions, 0 deletions

diff --git a/test/csv/parse/test_inputs_scanner.rb b/test/csv/parse/test_inputs_scanner.rb
new file mode 100644
index 0000000000..dd0a64cc45
--- /dev/null
+++ b/test/csv/parse/test_inputs_scanner.rb
@@ -0,0 +1,37 @@
+require_relative "../helper"
+
+class TestCSVParseInputsScanner < Test::Unit::TestCase
+  include Helper
+
+  def test_keep_over_chunks_nested_back
+    input = CSV::Parser::UnoptimizedStringIO.new("abcdefghijklmnl")
+    scanner = CSV::Parser::InputsScanner.new([input],
+                                             Encoding::UTF_8,
+                                             nil,
+                                             chunk_size: 2)
+    scanner.keep_start
+    assert_equal("abc", scanner.scan_all(/[a-c]+/))
+    scanner.keep_start
+    assert_equal("def", scanner.scan_all(/[d-f]+/))
+    scanner.keep_back
+    scanner.keep_back
+    assert_equal("abcdefg", scanner.scan_all(/[a-g]+/))
+  end
+
+
+  def test_keep_over_chunks_nested_drop_back
+    input = CSV::Parser::UnoptimizedStringIO.new("abcdefghijklmnl")
+    scanner = CSV::Parser::InputsScanner.new([input],
+                                             Encoding::UTF_8,
+                                             nil,
+                                             chunk_size: 3)
+    scanner.keep_start
+    assert_equal("ab", scanner.scan(/../))
+    scanner.keep_start
+    assert_equal("c", scanner.scan(/./))
+    assert_equal("d", scanner.scan(/./))
+    scanner.keep_drop
+    scanner.keep_back
+    assert_equal("abcdefg", scanner.scan_all(/[a-g]+/))
+  end
+end