test: Expand test failure message for debugging

wireservice · Jul 15, 2021 · b4f7b71 · b4f7b71
1 parent c6222f3
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Showing 3 changed files with 5 additions and 2 deletions.
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
@@ -7,6 +7,7 @@
 * feat: :class:`.TypeTester` accepts a ``null_values`` keyword argument. (#745)
 * feat: :class:`.Min`, :class:`.Max` and :class:`.Sum` (#735) work with :class:`.TimeDelta`.
 * feat: :class:`.FieldSizeLimitError` includes the line number in the error message. (#681)
+* feat: :class:`.csv.Sniffer` warns on error while sniffing CSV dialect.
 * fix: :meth:`.Table.normalize` works with basic processing methods. (#691)
 * fix: :meth:`.Table.homogenize` casts ``compare_values`` and ``default_row``. (#700)
 * fix: :meth:`.Table.homogenize` works with basic processing methods. (#756)

diff --git a/agate/csv_py2.py b/agate/csv_py2.py
@@ -250,7 +250,8 @@ def sniff(self, sample):
         """
         try:
             dialect = csv.Sniffer().sniff(sample, POSSIBLE_DELIMITERS)
-        except csv.Error:
+        except csv.Error as e:
+            warnings.warn('Error sniffing CSV dialect: %s' % e, RuntimeWarning, stacklevel=2)
             dialect = None
 
         return dialect

diff --git a/tests/test_py3.py b/tests/test_py3.py
@@ -252,4 +252,5 @@ def test_sniffer(self):
             contents = f.read()
             actual = csv_py3.Sniffer().sniff(contents).__dict__
             expected = csv.Sniffer().sniff(contents).__dict__
-            self.assertEqual(actual, expected, '%r != %r' % (actual, expected))
+            alternate = csv.Sniffer().sniff(contents, csv_py3.POSSIBLE_DELIMITERS).__dict__
+            self.assertEqual(actual, expected, '%r != %r (%r)' % (actual, expected, alternate))