Add a regression test for EPIPE IOErrors

This should prevent bug 69 from regressing in the future and provides a
framework for testing the addition of new errnos to the ingore list.

flake8/tests/test_reporter.py

@@ -0,0 +1,36 @@
+from __future__ import with_statement
+
+import errno
+import unittest
+try:
+    from unittest import mock
+except ImportError:
+    import mock  # < PY33
+
+from flake8 import reporter
+
+
+def ioerror_report_factory(errno_code):
+    class IOErrorBaseQReport(reporter.BaseQReport):
+        def _process_main(self):
+            raise IOError(errno_code, 'Fake bad pipe exception')
+
+    options = mock.MagicMock()
+    options.jobs = 2
+    return IOErrorBaseQReport(options)
+
+
+class TestBaseQReport(unittest.TestCase):
+    def test_does_not_raise_a_bad_pipe_ioerror(self):
+        """Test that no EPIPE IOError exception is re-raised or leaked."""
+        report = ioerror_report_factory(errno.EPIPE)
+        try:
+            report.process_main()
+        except IOError:
+            self.fail('BaseQReport.process_main raised an IOError for EPIPE'
+                      ' but it should have caught this exception.')
+
+    def test_raises_a_enoent_ioerror(self):
+        """Test that an ENOENT IOError exception is re-raised."""
+        report = ioerror_report_factory(errno.ENOENT)
+        self.assertRaises(IOError, report.process_main)