Make XFA pixel tests more stablechromium/3447

When generating PDFs using the fixup script and a .in, specify them to
to use Ahem.ttf as the text font. Ahem is a font designed to reduce
flakiness in pixel tests due to font rendering differences between
platforms. Specifically the glyphs in the font are standard size black
boxes, so though the specific text content cannot be easily compared,
things like layout and high level changes to the content can still
be tested. Testing things like specific text changes should be done
via an embedder test, where the strings in the elements can be
extracted and inspected.

The font itself is is CID type 2 font, which is relatively complex to
correctly embed in a PDF due to subsetting and other features. Instead
of embedding it in the generated PDFs, which was originally attempted,
it is being supplied to pdfium_test via the --font-dir flag. This flag
overrides where the binary looks for system fonts. This works
correctly on Mac and Linux, but not on Windows, which is why that
platform remains suppressed.

BUG=pdfium:1008,pdfium:1020

Change-Id: I00811536de98f736fc599d96b397194ccf8db0cd
Reviewed-on: https://pdfium-review.googlesource.com/27790
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

2 files changed, 16 insertions, 4 deletions

diff --git a/testing/tools/fixup_pdf_template.py b/testing/tools/fixup_pdf_template.py
index bee7a3d002..0f536785c1 100755
--- a/testing/tools/fixup_pdf_template.py
+++ b/testing/tools/fixup_pdf_template.py
@@ -30,11 +30,15 @@ import os
 import re
 import sys
 
+SCRIPT_PATH = os.path.abspath(os.path.dirname(__file__))
+
+
 class StreamLenState:
   START = 1
   FIND_STREAM = 2
   FIND_ENDSTREAM = 3
 
+
 class TemplateProcessor:
   HEADER_TOKEN = '{{header}}'
   HEADER_REPLACEMENT = '%PDF-1.7\n%\xa0\xf2\xa4\xf4'
@@ -45,7 +49,7 @@ class TemplateProcessor:
   XREF_REPLACEMENT_N = '%010d %05d n \n'
   XREF_REPLACEMENT_F = '0000000000 65535 f \n'
   # XREF rows must be exactly 20 bytes - space required.
-  assert(len(XREF_REPLACEMENT_F) == 20)
+  assert len(XREF_REPLACEMENT_F) == 20
 
   TRAILER_TOKEN = '{{trailer}}'
   TRAILER_REPLACEMENT = 'trailer <<\n  /Root 1 0 R\n  /Size %d\n>>'
@@ -230,7 +234,7 @@ class TemplateProcessor:
 
   def preprocess_line(self, line):
     if self.STREAMLEN_TOKEN in line:
-      assert(self.streamlen_state == StreamLenState.START)
+      assert self.streamlen_state == StreamLenState.START
       self.streamlen_state = StreamLenState.FIND_STREAM
       self.streamlens.append(0)
       return
diff --git a/testing/tools/test_runner.py b/testing/tools/test_runner.py
index 3fa1c79e04..3737969fb2 100644
--- a/testing/tools/test_runner.py
+++ b/testing/tools/test_runner.py
@@ -51,6 +51,8 @@ class TestRunner:
   # tests and outputfiles is a list tuples:
   #          (path_to_image, md5_hash_of_pixelbuffer)
   def GenerateAndTest(self, input_filename, source_dir):
+    use_ahem = 'use_ahem' in source_dir
+
     input_root, _ = os.path.splitext(input_filename)
     expected_txt_path = os.path.join(source_dir, input_root + '_expected.txt')
 
@@ -76,7 +78,7 @@ class TestRunner:
     if os.path.exists(expected_txt_path):
       raised_exception = self.TestText(input_root, expected_txt_path, pdf_path)
     else:
-      raised_exception, results = self.TestPixel(input_root, pdf_path)
+      raised_exception, results = self.TestPixel(input_root, pdf_path, use_ahem)
 
     if raised_exception is not None:
       print 'FAILURE: %s; %s' % (input_filename, raised_exception)
@@ -136,10 +138,15 @@ class TestRunner:
     cmd = [sys.executable, self.text_diff_path, expected_txt_path, txt_path]
     return common.RunCommand(cmd)
 
-  def TestPixel(self, input_root, pdf_path):
+  def TestPixel(self, input_root, pdf_path, use_ahem):
     cmd_to_run = [self.pdfium_test_path, '--send-events', '--png', '--md5']
+
     if self.oneshot_renderer:
       cmd_to_run.append('--render-oneshot')
+
+    if use_ahem:
+      cmd_to_run.append('--font-dir=%s' % self.font_dir)
+
     cmd_to_run.append(pdf_path)
     return common.RunCommandExtractHashedFiles(cmd_to_run)
 
@@ -219,6 +226,7 @@ class TestRunner:
     finder = common.DirectoryFinder(self.options.build_dir)
     self.fixup_path = finder.ScriptPath('fixup_pdf_template.py')
     self.text_diff_path = finder.ScriptPath('text_diff.py')
+    self.font_dir = os.path.join(finder.TestingDir(), 'resources', 'fonts')
 
     self.source_dir = finder.TestingDir()
     if self.test_dir != 'corpus':