Implement real output verification via iamge comparison. This strategy

seems to work very well.

src/z3c/rml/tests/test_rml.py

@@ -16,11 +16,16 @@
 $Id$
 """
 import os
+import PIL
+import popen2
 import unittest
 import sys
 import z3c.rml.tests
 from z3c.rml import rml2pdf, attr
 
+GS_COMMAND = ('gs -q -sNOPAUSE -sDEVICE=png256 -sOutputFile=%s[Page-%%d].png '
+              '%s -c quit')
+
 class RMLRenderingTestCase(unittest.TestCase):
 
     def __init__(self, inPath, outPath):
@@ -48,19 +53,68 @@ def runTest(self):
         rml2pdf.go(self._inPath, self._outPath)
 
 
+class ComparePDFTestCase(unittest.TestCase):
+
+    level = 2
+
+    def __init__(self, basePath, testPath):
+        self._basePath = basePath
+        self._testPath = testPath
+        unittest.TestCase.__init__(self)
+
+    def assertSameImage(self, baseImage, testImage):
+        base = PIL.Image.open(baseImage).getdata()
+        test = PIL.Image.open(testImage).getdata()
+        for i in range(len(base)):
+            if (base[i] - test[i]) != 0:
+                self.fail('Image is not the same.')
+
+    def runTest(self):
+        # Convert the base PDF to image(s)
+        status = popen2.Popen3(
+            GS_COMMAND %(self._basePath[:-4], self._basePath), True).wait()
+        if status:
+            return
+        # Convert the test PDF to image(s)
+        status = popen2.Popen3(
+            GS_COMMAND %(self._testPath[:-4], self._testPath), True).wait()
+        if status:
+            return
+        # Go through all pages and ensure their equality
+        n = 1
+        while True:
+            baseImage = self._basePath[:-4] + '[Page-%i].png' %n
+            testImage = self._testPath[:-4] + '[Page-%i].png' %n
+            if os.path.exists(baseImage) and os.path.exists(testImage):
+                self.assertSameImage(baseImage, testImage)
+            else:
+                break
+            n += 1
+
+
 def test_suite():
    suite = unittest.TestSuite()
    inputDir = os.path.join(os.path.dirname(z3c.rml.tests.__file__), 'input')
    outputDir = os.path.join(os.path.dirname(z3c.rml.tests.__file__), 'output')
+   expectDir = os.path.join(os.path.dirname(z3c.rml.tests.__file__), 'expected')
    for filename in os.listdir(inputDir):
        if not filename.endswith(".rml"):
            continue
        inPath = os.path.join(inputDir, filename)
        outPath = os.path.join(outputDir, filename[:-4] + '.pdf')
+       expectPath = os.path.join(expectDir, filename[:-4] + '.pdf')
+
+       # ** Test RML to PDF rendering **
        # Create new type, so that we can get test matching
        TestCase = type(filename[:-4], (RMLRenderingTestCase,), {})
        case = TestCase(inPath, outPath)
        suite.addTest(case)
+
+       # ** Test PDF rendering correctness **
+       TestCase = type('compare-'+filename[:-4], (ComparePDFTestCase,), {})
+       case = TestCase(expectPath, outPath)
+       suite.addTest(case)
+
    return suite
 
 if __name__ == '__main__':