text: import tempfile
  import pytest
  
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.util import ensure_list
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data.dataset_readers import Seq2SeqDatasetReader
  
  
  class TestSeq2SeqDatasetReader:
      @pytest.mark.parametrize("lazy", (True, False))
      def test_default_format(self, lazy):
          reader = Seq2SeqDatasetReader(lazy=lazy)
          instances = reader.read(str(AllenNlpTestCase.FIXTURES_ROOT / "data" / "seq2seq_copy.tsv"))
          instances = ensure_list(instances)
  
          assert len(instances) == 3
          fields = instances[0].fields
          assert [t.text for t in fields["source_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "sentence",
              "@end@",
          ]
          assert [t.text for t in fields["target_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "sentence",
              "@end@",
          ]
          fields = instances[1].fields
          assert [t.text for t in fields["source_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "another",
              "@end@",
          ]
          assert [t.text for t in fields["target_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "another",
              "@end@",
          ]
          fields = instances[2].fields
          assert [t.text for t in fields["source_tokens"].tokens] == [
              "@start@",
              "all",
              "these",
              "sentences",
              "should",
              "get",
              "copied",
              "@end@",
          ]
          assert [t.text for t in fields["target_tokens"].tokens] == [
              "@start@",
              "all",
              "these",
              "sentences",
              "should",
              "get",
              "copied",
              "@end@",
          ]
  
      def test_source_add_start_token(self):
          reader = Seq2SeqDatasetReader(source_add_start_token=False)
          instances = reader.read(str(AllenNlpTestCase.FIXTURES_ROOT / "data" / "seq2seq_copy.tsv"))
          instances = ensure_list(instances)
  
          assert len(instances) == 3
          fields = instances[0].fields
          assert [t.text for t in fields["source_tokens"].tokens] == [
              "this",
              "is",
              "a",
              "sentence",
              "@end@",
          ]
          assert [t.text for t in fields["target_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "sentence",
              "@end@",
          ]
  
      def test_source_add_end_token(self):
          reader = Seq2SeqDatasetReader(source_add_end_token=False)
          instances = reader.read(str(AllenNlpTestCase.FIXTURES_ROOT / "data" / "seq2seq_copy.tsv"))
          instances = ensure_list(instances)
  
          assert len(instances) == 3
          fields = instances[0].fields
          assert [t.text for t in fields["source_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "sentence",
          ]
          assert [t.text for t in fields["target_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "sentence",
              "@end@",
          ]
  
      def test_max_length_truncation(self):
          reader = Seq2SeqDatasetReader(source_max_tokens=3, target_max_tokens=5)
          instances = reader.read(str(AllenNlpTestCase.FIXTURES_ROOT / "data" / "seq2seq_copy.tsv"))
          instances = ensure_list(instances)
          assert reader._source_max_exceeded == 2
          assert reader._target_max_exceeded == 1
          assert len(instances) == 3
          fields = instances[0].fields
          assert [t.text for t in fields["source_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "@end@",
          ]
          assert [t.text for t in fields["target_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "sentence",
              "@end@",
          ]
  
      def test_delimiter_parameter(self):
          reader = Seq2SeqDatasetReader(delimiter=",")
          instances = reader.read(str(AllenNlpTestCase.FIXTURES_ROOT / "data" / "seq2seq_copy.csv"))
          instances = ensure_list(instances)
  
          assert len(instances) == 3
          fields = instances[0].fields
          assert [t.text for t in fields["source_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "sentence",
              "@end@",
          ]
          assert [t.text for t in fields["target_tokens"].tokens] == [
              "@start@",
              "this",
              "is",
              "a",
              "sentence",
              "@end@",
          ]
          fields = instances[2].fields
          assert [t.text for t in fields["source_tokens"].tokens] == [
              "@start@",
              "all",
              "these",
              "sentences",
              "should",
              "get",
              "copied",
              "@end@",
          ]
          assert [t.text for t in fields["target_tokens"].tokens] == [
              "@start@",
              "all",
              "these",
              "sentences",
              "should",
              "get",
              "copied",
              "@end@",
          ]
  
      @pytest.mark.parametrize("line", (("a\n"), ("a\tb\tc\n")))
      def test_invalid_line_format(self, line):
          with tempfile.NamedTemporaryFile("w") as fp_tmp:
              fp_tmp.write(line)
              fp_tmp.flush()
              reader = Seq2SeqDatasetReader()
              with pytest.raises(ConfigurationError):
                  reader.read(fp_tmp.name)
  
      @pytest.mark.parametrize("line", (("a b\tc d\n"), ('"a b"\t"c d"\n')))
      def test_correct_quote_handling(self, line):
          with tempfile.NamedTemporaryFile("w") as fp_tmp:
              fp_tmp.write(line)
              fp_tmp.flush()
              reader = Seq2SeqDatasetReader()
              instances = reader.read(fp_tmp.name)
              instances = ensure_list(instances)
              assert len(instances) == 1
              fields = instances[0].fields
              assert [t.text for t in fields["source_tokens"].tokens] == [
                  "@start@",
                  "a",
                  "b",
                  "@end@",
              ]
              assert [t.text for t in fields["target_tokens"].tokens] == [
                  "@start@",
                  "c",
                  "d",
                  "@end@",
              ]
  