Add test for rec2csv and csv2rec roundtrip not losing precision.

svn path=/trunk/matplotlib/; revision=4747

Author: astraw

unit/mlab_unit.py

@@ -0,0 +1,38 @@
+import unittest
+import matplotlib.mlab as mlab
+import numpy
+import StringIO
+
+class TestMlab(unittest.TestCase):
+    def test_csv2rec_closefile(self):
+        # If passed a file-like object, rec2csv should not close it.
+        ra=numpy.rec.array([(123, 1197346475.0137341), (456, 123.456)],
+                           dtype=[('a', '<i8'), ('b', '<f8')])
+        fh = StringIO.StringIO()
+        mlab.rec2csv( ra, fh )
+        self.failIf( fh.closed )
+
+    def test_csv2rec_roundtrip(self):
+        # Make sure double-precision floats pass through.
+
+        # A bug in numpy (fixed in r4602) meant that numpy scalars
+        # lost precision when passing through repr(). csv2rec was
+        # affected by this. This test will only pass on numpy >=
+        # 1.0.5.
+        ra=numpy.rec.array([(123, 1197346475.0137341), (456, 123.456)],
+                           dtype=[('a', '<i8'), ('b', '<f8')])
+        rec2csv_closes_files = True
+        if rec2csv_closes_files:
+            fh = 'mlab_unit_tmp.csv'
+        else:
+            fh = StringIO.StringIO()
+        mlab.rec2csv( ra, fh )
+        if not rec2csv_closes_files:
+            fh.seek(0)
+        ra2 = mlab.csv2rec(fh)
+        for name in ra.dtype.names:
+            #print name, repr(ra[name]), repr(ra2[name])
+            self.failUnless( numpy.all(ra[name] == ra2[name]) ) # should not fail with numpy 1.0.5
+
+if __name__=='__main__':
+    unittest.main()