Unit tests - add 'images_almost_equal(im1, im2, tol)` + update reprojection_test.

Author: artemp

test/python_tests/reprojection_test.py

@@ -1,7 +1,7 @@
 import os
 import mapnik
 import pytest
-from .utilities import execution_path
+from .utilities import execution_path, images_almost_equal
 
 @pytest.fixture(scope="module")
 def setup():
@@ -25,13 +25,13 @@ def test_zoom_all_will_work_with_max_extent():
         m.zoom_all()
         # note - fixAspectRatio is being called, then re-clipping to maxextent
         # which makes this hard to predict
-        # assert m.envelope() ==merc_bounds
+        #assert m.envelope() == merc_bounds
 
-        #m = mapnik.Map(512,512)
-        # mapnik.load_map(m,'../data/good_maps/wgs842merc_reprojection.xml')
-        #merc_bounds = mapnik.Box2d(-20037508.34,-20037508.34,20037508.34,20037508.34)
-        # m.zoom_to_box(merc_bounds)
-        # assert m.envelope() ==merc_bounds
+        m = mapnik.Map(512,512)
+        mapnik.load_map(m,'../data/good_maps/wgs842merc_reprojection.xml')
+        merc_bounds = mapnik.Box2d(-20037508.34,-20037508.34,20037508.34,20037508.34)
+        m.zoom_to_box(merc_bounds)
+        assert m.envelope() == merc_bounds
 
     def test_visual_zoom_all_rendering1():
         m = mapnik.Map(512, 512)
@@ -45,21 +45,16 @@ def test_visual_zoom_all_rendering1():
         expected = 'images/support/mapnik-wgs842merc-reprojection-render.png'
         im.save(actual, 'png32')
         expected_im = mapnik.Image.open(expected)
-        assert im.tostring('png32') == expected_im.tostring('png32'), 'failed comparing actual (%s) and expected (%s)' % (actual,
-                                                                                                                          'test/python_tests/' + expected)
+        images_almost_equal(im, expected_im)
 
     def test_visual_zoom_all_rendering2():
         m = mapnik.Map(512, 512)
         mapnik.load_map(m, '../data/good_maps/merc2wgs84_reprojection.xml')
         m.zoom_all()
         im = mapnik.Image(512, 512)
         mapnik.render(m, im)
-        actual = '/tmp/mapnik-merc2wgs84-reprojection-render.png'
-        expected = 'images/support/mapnik-merc2wgs84-reprojection-render.png'
-        im.save(actual, 'png32')
-        expected_im = mapnik.Image.open(expected)
-        assert im.tostring('png32') == expected_im.tostring('png32'),'failed comparing actual (%s) and expected (%s)' % (actual,
-                                                                                                                         'test/python_tests/' + expected)
+        expected_im = mapnik.Image.open('images/support/mapnik-merc2wgs84-reprojection-render.png')
+        images_almost_equal(im, expected_im)
 
     # maximum-extent read from map.xml
     def test_visual_zoom_all_rendering3():
@@ -68,12 +63,9 @@ def test_visual_zoom_all_rendering3():
         m.zoom_all()
         im = mapnik.Image(512, 512)
         mapnik.render(m, im)
-        actual = '/tmp/mapnik-merc2merc-reprojection-render1.png'
         expected = 'images/support/mapnik-merc2merc-reprojection-render1.png'
-        im.save(actual, 'png32')
         expected_im = mapnik.Image.open(expected)
-        assert im.tostring('png32') == expected_im.tostring('png32'), 'failed comparing actual (%s) and expected (%s)' % (actual,
-                                                                                                                          'test/python_tests/' + expected)
+        images_almost_equal(im, expected_im)
 
     # no maximum-extent
     def test_visual_zoom_all_rendering4():
@@ -83,8 +75,6 @@ def test_visual_zoom_all_rendering4():
         m.zoom_all()
         im = mapnik.Image(512, 512)
         mapnik.render(m, im)
-        actual = '/tmp/mapnik-merc2merc-reprojection-render2.png'
         expected = 'images/support/mapnik-merc2merc-reprojection-render2.png'
-        im.save(actual, 'png32')
         expected_im = mapnik.Image.open(expected)
-        assert im.tostring('png32') == expected_im.tostring('png32'),'failed comparing actual (%s) and expected (%s)' % (actual, 'test/python_tests/' + expected)
+        images_almost_equal(im, expected_im)

test/python_tests/utilities.py

@@ -97,3 +97,15 @@ def assert_box2d_almost_equal(a, b, msg=None):
     assert a.maxx == pytest.approx(b.maxx, abs=1e-2), msg
     assert a.miny == pytest.approx(b.miny, abs=1e-2), msg
     assert a.maxy == pytest.approx(b.maxy, abs=1e-2), msg
+
+
+def images_almost_equal(image1, image2, tolerance = 1):
+    def rgba(p):
+        return p & 0xff,(p >> 8) & 0xff,(p >> 16) & 0xff, p >> 24
+    assert image1.width()  == image2.width()
+    assert image1.height() == image2.height()
+    for x in range(image1.width()):
+        for y in range(image1.height()):
+            p1 = image1.get_pixel(x, y)
+            p2 = image2.get_pixel(x, y)
+            assert rgba(p1) == pytest.approx(rgba(p2), abs = tolerance)