New tests by Nick Mathewson, for the fpformat module.

This closes SF patch #440290.

Lib/test/test_fpformat.py

@@ -0,0 +1,67 @@
+'''
+   Tests for fpformat module
+   Nick Mathewson
+'''
+from test_support import run_unittest
+import unittest
+from fpformat import fix, sci, NotANumber
+
+StringType = type('')
+
+# Test the old and obsolescent fpformat module.
+#
+# (It's obsolescent because fix(n,d) == "%.*f"%(d,n) and 
+#                           sci(n,d) == "%.*e"%(d,n)
+#  for all reasonable numeric n and d, except that sci gives 3 exponent 
+#  digits instead of 2.  
+#
+# Differences only occur for unreasonable n and d.    <.2 wink>)
+
+class FpformatTest(unittest.TestCase):
+
+    def checkFix(self, n, digits):
+        result = fix(n, digits)
+        if isinstance(n, StringType):
+            n = repr(n)
+        expected = "%.*f" % (digits, float(n))
+
+        self.assertEquals(result, expected)
+
+    def checkSci(self, n, digits):
+        result = sci(n, digits)
+        if isinstance(n, StringType):
+            n = repr(n)
+        expected = "%.*e" % (digits, float(n))
+        # add the extra 0
+        expected = expected[:-2]+'0'+expected[-2:]
+
+        self.assertEquals(result, expected)
+
+    def test_basic_cases(self):
+        self.assertEquals(fix(100.0/3, 3), '33.333')
+        self.assertEquals(sci(100.0/3, 3), '3.333e+001')
+
+    def test_reasonable_values(self):
+        for d in range(7):
+            for val in (1000.0/3, 1000, 1000.0, .002, 1.0/3, 1e10):
+                for realVal in (val, 1.0/val, -val, -1.0/val):
+                    self.checkFix(realVal, d)
+                    self.checkSci(realVal, d)
+
+    def test_failing_values(self):
+        # Now for 'unreasonable n and d'
+        self.assertEquals(fix(1.0, 1000), '1.'+('0'*1000))
+        self.assertEquals(sci("1"+('0'*1000), 0), '1e+1000')
+
+        # This behavior is inconsistent.  sci raises an exception; fix doesn't.
+        yacht = "Throatwobbler Mangrove"
+        self.assertEquals(fix(yacht, 10), yacht)
+        try:
+            sci(yacht, 10)
+        except NotANumber:
+            pass
+        else:
+            self.fail("No exception on non-numeric sci")
+
+run_unittest(FpformatTest)
+