```# Test the flat geometry manager for conformance to the required interface

import unittest
import numpy as N
import math

from tracer.flat_surface import FlatGeometryManager
from tracer.ray_bundle import RayBundle

class TestFlatGeomManagerInterface(unittest.TestCase):
def setUp(self):
dir = N.c_[[1, 1, -1], [-1, 1, -1], [-1, -1, -1], [1, -1, -1]] / math.sqrt(3)
position = N.c_[[0,0,1], [1,-1,1], [1,1,1], [-1,1,1]]
self._bund = RayBundle(position, dir)

self.gm = FlatGeometryManager()
self.prm = self.gm.find_intersections(N.eye(4), self._bund)

def test_find_intersections(self):
"""The correct parametric locations are found for flat geometry"""
self.failUnlessEqual(self.prm.shape, (4,),
"Shape of parametric location array is wrong: " + \
str(self.prm.shape))
N.testing.assert_array_almost_equal(self.prm, N.sqrt(3))

def test_get_normals(self):
"""A flat geometry manager returns parallel normals"""
self.gm.select_rays(N.arange(4))
n = self.gm.get_normals()
N.testing.assert_array_equal(n, N.tile(N.c_[[0, 0, 1]], (1,4)))

def test_select_rays_normals(self):
"""Correct normals when some rays not selected"""
self.gm.select_rays(N.r_[1,3])
n = self.gm.get_normals()
N.testing.assert_array_equal(n, N.tile(N.c_[[0, 0, 1]], (1,2)))

def test_inters_points_global(self):
"""On the basic setup, a flat surface returns correct intersections"""
correct_pts = N.zeros((3,4))
correct_pts[:2,0] = 1

self.gm.select_rays(N.arange(4))
pts = self.gm.get_intersection_points_global()
N.testing.assert_array_equal(pts, correct_pts)

def select_rays_inters(self):
"""Correct intersections when some rays not selected"""
correct_pts = N.zeros((3,2))
correct_pts[:2,0] = 1
pts = self.gm.get_intersection_points_global()
N.testing.assert_array_equal(pts, correct_pts)

import tracer.spatial_geometry as SP
class TestFlatGeomTilted(unittest.TestCase):
"""Use a flat surface rotated about the x axis by 45 degrees"""
def setUp(self):
s2 = math.sqrt(2)
dir = N.c_[[1, 0, -s2], [-1, 0, -s2], [-1, -s2, 0], [1, -s2, 0]] / math.sqrt(3)
position = N.c_[[0,1/s2,1/s2], [1,0,s2], [1,s2,0], [-1,s2,0]]
self._bund = RayBundle(position, dir)

self.gm = FlatGeometryManager()
frame = SP.generate_transform(N.r_[1., 0, 0], -N.pi/4., N.zeros((3,1)))
self.prm = self.gm.find_intersections(frame, self._bund)

def test_find_intersections(self):
"""The correct parametric locations are found for flat geometry"""
self.failUnlessEqual(self.prm.shape, (4,),
"Shape of parametric location array is wrong: " + \
str(self.prm.shape))
N.testing.assert_array_almost_equal(self.prm, math.sqrt(3))

def test_get_normals(self):
"""A tilted flat geometry manager returns parallel normals"""
s2 = math.sqrt(2)
self.gm.select_rays(N.arange(4))
n = self.gm.get_normals()
N.testing.assert_array_almost_equal(n, N.tile(N.c_[[0,1/s2,1/s2]], (1,4)))

def test_select_rays_normals(self):
"""A tilted flat geometry manager returns normals only for selected rays"""
s2 = math.sqrt(2)
self.gm.select_rays(N.r_[1,3])
n = self.gm.get_normals()
N.testing.assert_array_almost_equal(n, N.tile(N.c_[[0,1/s2,1/s2]], (1,2)))

def test_inters_points_global(self):
"""On the basic setup, a tilted flat surface returns correct intersections"""
correct_pts = N.zeros((3,4))
s2 = math.sqrt(2)
correct_pts[:,0] = N.r_[1, 1/s2, -1/s2]

self.gm.select_rays(N.arange(4))
pts = self.gm.get_intersection_points_global()
N.testing.assert_array_almost_equal(pts, correct_pts)

def test_select_rays_inters(self):
"""With dropped rays, a tilted flat surface returns correct intersections"""
s2 = math.sqrt(2)
correct_pts = N.zeros((3,2))

self.gm.select_rays(N.r_[1,3])
pts = self.gm.get_intersection_points_global()
N.testing.assert_array_almost_equal(pts, correct_pts)

class TestFlatGeomTranslated(unittest.TestCase):
def setUp(self):
dir = N.c_[[1, 1, -1], [-1, 1, -1], [-1, -1, -1], [1, -1, -1]] / math.sqrt(3)
position = N.c_[[0,0,1], [1,-1,1], [1,1,1], [-1,1,1]]
self._bund = RayBundle(position, dir)

self.gm = FlatGeometryManager()
frame = SP.translate(1., 0., 0.)
self.prm = self.gm.find_intersections(frame, self._bund)

def test_find_intersections(self):
"""The correct parametric locations are found for translated flat geometry"""
self.failUnlessEqual(self.prm.shape, (4,),
"Shape of parametric location array is wrong: " + \
str(self.prm.shape))
N.testing.assert_array_almost_equal(self.prm, N.sqrt(3))

def test_get_normals(self):
"""A translated flat geometry manager returns parallel normals"""
self.gm.select_rays(N.arange(4))
n = self.gm.get_normals()
N.testing.assert_array_equal(n, N.tile(N.c_[[0, 0, 1]], (1,4)))

def test_inters_points_global(self):
"""When translated, a flat surface returns correct intersections"""
correct_pts = N.zeros((3,4))
correct_pts[:2,0] = 1

self.gm.select_rays(N.arange(4))
pts = self.gm.get_intersection_points_global()
N.testing.assert_array_equal(pts, correct_pts)

class TestBacksideNormals(unittest.TestCase):
def setUp(self):
dir = N.c_[[1, 1, 1], [-1, 1, 1], [-1, -1, 1], [1, -1, 1]] / math.sqrt(3)
position = N.c_[[0,0,-1], [1,-1,-1], [1,1,-1], [-1,1,-1]]
self._bund = RayBundle(position, dir)

self.gm = FlatGeometryManager()
self.prm = self.gm.find_intersections(N.eye(4), self._bund)

def test_get_normals(self):
"""A translated flat geometry manager returns parallel normals"""
self.gm.select_rays(N.arange(4))
n = self.gm.get_normals()
N.testing.assert_array_equal(n, N.tile(N.c_[[0, 0, -1]], (1,4)))

```