add unit test code

python/desc/imsim/flats.py

@@ -42,7 +42,7 @@ def make_flat(gs_det, counts_per_iter, niter, rng, buf=2, logger=None,
     galsim.ImageF
     """
     if logger is None:
-        logger = desc.imsim.get_logger('INFO', name='make_flat')
+        logger = desc.imsim.get_logger('DEBUG', name='make_flat')
     if wcs is None:
         wcs = gs_det.wcs
     ncol = gs_det.xMaxPix - gs_det.xMinPix + 1

tests/test_flats.py

@@ -0,0 +1,50 @@
+"""
+Unit test code for flat production code.
+"""
+from collections import namedtuple
+import unittest
+import numpy as np
+import galsim
+import desc.imsim
+
+TreeRingInfo = namedtuple('TreeRingInfo', ['center', 'func'])
+
+class GsDetector:
+    """
+    Minimal implementation of an interface-compatible version
+    of GalSimDetector for testing the flat production code.
+    """
+    def __init__(self):
+        self.xMaxPix = 256
+        self.yMaxPix = 256
+        self.xMinPix = 1
+        self.yMinPix = 1
+        self.wcs = galsim.wcs.PixelScale(0.2)
+        self.tree_rings \
+            = TreeRingInfo(galsim.PositionD(0, 0),
+                           galsim.SiliconSensor.simple_treerings(0.26, 47))
+
+
+class FlatTestCase(unittest.TestCase):
+    """TestCase class for flat production code."""
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    def test_make_flat(self):
+        """Test of make_flat function."""
+        gs_det = GsDetector()
+        counts_per_iter = 1000
+        niter = 10
+        rng = galsim.UniformDeviate()
+        logger = desc.imsim.get_logger('WARN')
+        flat = desc.imsim.make_flat(gs_det, counts_per_iter, niter, rng,
+                                    logger=logger)
+        self.assertLess(np.abs(niter*counts_per_iter - flat.array.mean()),
+                        flat.array.std())
+
+
+if __name__ == '__main__':
+    unittest.main()