Lib/test/test_fpformat.py

   1 '''
   2    Tests for fpformat module
   3    Nick Mathewson
   4 '''
   5 from test.test_support import run_unittest
   6 import unittest
   7 from fpformat import fix, sci, NotANumber
   8
   9 StringType = type('')
  10
  11 # Test the old and obsolescent fpformat module.
  12 #
  13 # (It's obsolescent because fix(n,d) == "%.*f"%(d,n) and
  14 #                           sci(n,d) == "%.*e"%(d,n)
  15 #  for all reasonable numeric n and d, except that sci gives 3 exponent
  16 #  digits instead of 2.
  17 #
  18 # Differences only occur for unreasonable n and d.    <.2 wink>)
  19
  20 class FpformatTest(unittest.TestCase):
  21
  22     def checkFix(self, n, digits):
  23         result = fix(n, digits)
  24         if isinstance(n, StringType):
  25             n = repr(n)
  26         expected = "%.*f" % (digits, float(n))
  27
  28         self.assertEquals(result, expected)
  29
  30     def checkSci(self, n, digits):
  31         result = sci(n, digits)
  32         if isinstance(n, StringType):
  33             n = repr(n)
  34         expected = "%.*e" % (digits, float(n))
  35         # add the extra 0 if needed
  36         num, exp = expected.split("e")
  37         if len(exp) < 4:
  38             exp = exp[0] + "0" + exp[1:]
  39         expected = "%se%s" % (num, exp)
  40
  41         self.assertEquals(result, expected)
  42
  43     def test_basic_cases(self):
  44         self.assertEquals(fix(100.0/3, 3), '33.333')
  45         self.assertEquals(sci(100.0/3, 3), '3.333e+001')
  46
  47     def test_reasonable_values(self):
  48         for d in range(7):
  49             for val in (1000.0/3, 1000, 1000.0, .002, 1.0/3, 1e10):
  50                 for realVal in (val, 1.0/val, -val, -1.0/val):
  51                     self.checkFix(realVal, d)
  52                     self.checkSci(realVal, d)
  53
  54     def test_failing_values(self):
  55         # Now for 'unreasonable n and d'
  56         self.assertEquals(fix(1.0, 1000), '1.'+('0'*1000))
  57         self.assertEquals(sci("1"+('0'*1000), 0), '1e+1000')
  58
  59         # This behavior is inconsistent.  sci raises an exception; fix doesn't.
  60         yacht = "Throatwobbler Mangrove"
  61         self.assertEquals(fix(yacht, 10), yacht)
  62         try:
  63             sci(yacht, 10)
  64         except NotANumber:
  65             pass
  66         else:
  67             self.fail("No exception on non-numeric sci")
  68
  69
  70 def test_main():
  71     run_unittest(FpformatTest)
  72
  73
  74 if __name__ == "__main__":
  75     test_main()