Test stream detaching in CsvItemExporter

scrapy/exporters.py

@@ -248,10 +248,7 @@ class CsvItemExporter(BaseItemExporter):
         self.csv_writer.writerow(values)
 
     def finish_exporting(self):
-        # Detaching stream in order to avoid file closing.
-        # The file will be closed with slot.storage.store
-        # https://github.com/scrapy/scrapy/issues/5043
-        self.stream.detach()
+        self.stream.detach()  # Avoid closing the wrapped file.
 
     def _build_row(self, values):
         for s in values:

tests/test_exporters.py

@@ -85,6 +85,10 @@ class BaseItemExporterTest(unittest.TestCase):
             if self.ie.__class__ is not BaseItemExporter:
                 raise
         self.ie.finish_exporting()
+        # Delete the item exporter object, so that if it causes the output
+        # file handle be closed, which should not be the case, follow-up
+        # interactions with the output file handle will surface the issue.
+        del self.ie
         self._check_output()
 
     def test_export_item(self):
@@ -230,6 +234,7 @@ class PickleItemExporterTest(BaseItemExporterTest):
         ie.export_item(i1)
         ie.export_item(i2)
         ie.finish_exporting()
+        del ie  # See the first “del self.ie” in this file for context.
         f.seek(0)
         self.assertEqual(self.item_class(**pickle.load(f)), i1)
         self.assertEqual(self.item_class(**pickle.load(f)), i2)
@@ -241,6 +246,7 @@ class PickleItemExporterTest(BaseItemExporterTest):
         ie.start_exporting()
         ie.export_item(item)
         ie.finish_exporting()
+        del ie  # See the first “del self.ie” in this file for context.
         self.assertEqual(pickle.loads(fp.getvalue()), item)
 
 
@@ -267,6 +273,7 @@ class MarshalItemExporterTest(BaseItemExporterTest):
         ie.start_exporting()
         ie.export_item(item)
         ie.finish_exporting()
+        del ie  # See the first “del self.ie” in this file for context.
         fp.seek(0)
         self.assertEqual(marshal.load(fp), item)
 
@@ -299,6 +306,7 @@ class CsvItemExporterTest(BaseItemExporterTest):
         ie.start_exporting()
         ie.export_item(item)
         ie.finish_exporting()
+        del ie  # See the first “del self.ie” in this file for context.
         self.assertCsvEqual(fp.getvalue(), expected)
 
     def test_header_export_all(self):
@@ -330,6 +338,7 @@ class CsvItemExporterTest(BaseItemExporterTest):
             ie.export_item(item)
             ie.export_item(item)
             ie.finish_exporting()
+            del ie  # See the first “del self.ie” in this file for context.
             self.assertCsvEqual(output.getvalue(),
                                 b'age,name\r\n22,John\xc2\xa3\r\n22,John\xc2\xa3\r\n')
 
@@ -414,6 +423,7 @@ class XmlItemExporterTest(BaseItemExporterTest):
         ie.start_exporting()
         ie.export_item(item)
         ie.finish_exporting()
+        del ie  # See the first “del self.ie” in this file for context.
         self.assertXmlEquivalent(fp.getvalue(), expected_value)
 
     def _check_output(self):
@@ -520,6 +530,7 @@ class JsonLinesItemExporterTest(BaseItemExporterTest):
         self.ie.start_exporting()
         self.ie.export_item(i3)
         self.ie.finish_exporting()
+        del self.ie  # See the first “del self.ie” in this file for context.
         exported = json.loads(to_unicode(self.output.getvalue()))
         self.assertEqual(exported, self._expected_nested)
 
@@ -534,6 +545,7 @@ class JsonLinesItemExporterTest(BaseItemExporterTest):
         self.ie.start_exporting()
         self.ie.export_item(item)
         self.ie.finish_exporting()
+        del self.ie  # See the first “del self.ie” in this file for context.
         exported = json.loads(to_unicode(self.output.getvalue()))
         item['time'] = str(item['time'])
         self.assertEqual(exported, item)
@@ -561,6 +573,7 @@ class JsonItemExporterTest(JsonLinesItemExporterTest):
         self.ie.export_item(item)
         self.ie.export_item(item)
         self.ie.finish_exporting()
+        del self.ie  # See the first “del self.ie” in this file for context.
         exported = json.loads(to_unicode(self.output.getvalue()))
         self.assertEqual(exported, [ItemAdapter(item).asdict(), ItemAdapter(item).asdict()])
 
@@ -577,6 +590,7 @@ class JsonItemExporterTest(JsonLinesItemExporterTest):
         self.ie.start_exporting()
         self.ie.export_item(i3)
         self.ie.finish_exporting()
+        del self.ie  # See the first “del self.ie” in this file for context.
         exported = json.loads(to_unicode(self.output.getvalue()))
         expected = {'name': 'Jesus', 'age': {'name': 'Maria', 'age': ItemAdapter(i1).asdict()}}
         self.assertEqual(exported, [expected])
@@ -588,6 +602,7 @@ class JsonItemExporterTest(JsonLinesItemExporterTest):
         self.ie.start_exporting()
         self.ie.export_item(i3)
         self.ie.finish_exporting()
+        del self.ie  # See the first “del self.ie” in this file for context.
         exported = json.loads(to_unicode(self.output.getvalue()))
         expected = {'name': 'Jesus', 'age': {'name': 'Maria', 'age': i1}}
         self.assertEqual(exported, [expected])
@@ -597,6 +612,7 @@ class JsonItemExporterTest(JsonLinesItemExporterTest):
         self.ie.start_exporting()
         self.ie.export_item(item)
         self.ie.finish_exporting()
+        del self.ie  # See the first “del self.ie” in this file for context.
         exported = json.loads(to_unicode(self.output.getvalue()))
         item['time'] = str(item['time'])
         self.assertEqual(exported, [item])