Lib/test/test_StringIO.py

# Tests StringIO and cStringIO

import sys
import unittest
import io
from test import test_support


class TestGenericStringIO:
    # use a class variable CLASS to define which class is being tested
    CLASS = None

    # Line of data to test as string
    _line = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!'

    # Constructor to use for the test data (._line is passed to this
    # constructor)
    constructor = str

    def setUp(self):
        self._line = self.constructor(self._line)
        self._lines = self.constructor((self._line + '\n') * 5)
        self._fp = self.CLASS(self._lines)

    def test_reads(self):
        eq = self.assertEqual
        self.assertRaises(TypeError, self._fp.seek)
        eq(self._fp.read(10), self._line[:10])
        eq(self._fp.readline(), self._line[10:] + '\n')
        eq(len(self._fp.readlines(60)), 2)

    def test_writes(self):
        f = self.CLASS()
        self.assertRaises(TypeError, f.seek)
        f.write(self._line[:6])
        f.seek(3)
        f.write(self._line[20:26])
        f.write(self._line[52])
        self.assertEqual(f.getvalue(), 'abcuvwxyz!')

    def test_writelines(self):
        f = self.CLASS()
        f.writelines([self._line[0], self._line[1], self._line[2]])
        f.seek(0)
        self.assertEqual(f.getvalue(), 'abc')

    def test_writelines_error(self):
        def errorGen():
            yield 'a'
            raise KeyboardInterrupt()
        f = self.CLASS()
        self.assertRaises(KeyboardInterrupt, f.writelines, errorGen())

    def test_truncate(self):
        eq = self.assertEqual
        f = self.CLASS()
        f.write(self._lines)
        f.seek(10)
        f.truncate()
        eq(f.getvalue(), 'abcdefghij')
        f.truncate(5)
        eq(f.getvalue(), 'abcde')
        f.write('xyz')
        eq(f.getvalue(), 'abcdexyz')
        self.assertRaises(ValueError, f.truncate, -1)
        f.close()
        self.assertRaises(ValueError, f.write, 'frobnitz')

    def test_closed_flag(self):
        f = self.CLASS()
        self.assertEqual(f.closed, False)
        f.close()
        self.assertEqual(f.closed, True)
        f = self.CLASS(self.constructor("abc"))
        self.assertEqual(f.closed, False)
        f.close()
        self.assertEqual(f.closed, True)

    def test_isatty(self):
        f = self.CLASS()
        self.assertRaises(TypeError, f.isatty, None)
        self.assertEqual(f.isatty(), False)
        f.close()
        self.assertRaises(ValueError, f.isatty)

    def test_iterator(self):
        eq = self.assertEqual
        unless = self.failUnless
        eq(iter(self._fp), self._fp)
        # Does this object support the iteration protocol?
        unless(hasattr(self._fp, '__iter__'))
        unless(hasattr(self._fp, '__next__'))
        i = 0
        for line in self._fp:
            eq(line, self._line + '\n')
            i += 1
        eq(i, 5)
        self._fp.close()
        self.assertRaises(StopIteration, next, self._fp)

class TestioStringIO(TestGenericStringIO, unittest.TestCase):
    CLASS = io.StringIO

    def test_unicode(self):

        if not test_support.have_unicode: return

        # The StringIO module also supports concatenating Unicode
        # snippets to larger Unicode strings. This is tested by this
        # method. Note that cStringIO does not support this extension.

        f = self.CLASS()
        f.write(self._line[:6])
        f.seek(3)
        f.write(str(self._line[20:26]))
        f.write(str(self._line[52]))
        s = f.getvalue()
        self.assertEqual(s, str('abcuvwxyz!'))
        self.assertEqual(type(s), str)


def test_main():
    test_support.run_unittest(TestioStringIO)


if __name__ == '__main__':
    test_main()