Issue 7059 - Modify fldiff so it can handle multiple files

tests/test_diff_script.py

 # This file is part of Adblock Plus <https://adblockplus.org/>,
 # Copyright (C) 2006-present eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
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 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ skipping 10 matching lines @@
 import subprocess
 import io
 import os
 import re
 
 from test_differ import BASE, LATEST
 
 
 @pytest.fixture
 def rootdir(tmpdir):
-    """Root directory holds the latest filter list, and folders for archived

[Vasily Kuznetsov, 2018/10/31 14:42:39]

Multiline docstrings should "consist of a summary line just like a one-line
docstring, followed by a blank line, followed by a more elaborate description"
accodring to PEP257 [1], which is recommended by our style guide. In this case I
think there are two approaches to make this docstring compatible: either
reformulate it and make it short enough to fit into one line or do something
like:

    """Root directory for test files.

    Yada yada yada.
    """

[1]: https://www.python.org/dev/peps/pep-0257/#multi-line-docstrings

[rhowell, 2018/10/31 19:11:46]

Oops, thanks! I knew the multiline docstring looked weird, but I forgot it's in
the style guide. I shortened it; hopefully the code is clear enough so we don't
need as much documentation.

-    lists and diffs."""
+    """Root directory for test files."""
     rootdir = tmpdir.join('root')
     rootdir.mkdir()
     rootdir.join('latest.txt').write_text(LATEST, encoding='utf8')
     return rootdir
 
 
 @pytest.fixture
 def archive_dir(rootdir):
     return rootdir.mkdir('archive')
 
@@ skipping 26 matching lines @@
     proc = subprocess.Popen(cmd, stderr=subprocess.PIPE,
                             stdout=subprocess.PIPE, stdin=subprocess.PIPE,
                             **kw)
     stdout, stderr = proc.communicate()
     return proc.returncode, stderr.decode('utf-8'), stdout.decode('utf-8')
 
 
 def test_diff_with_outfile(rootdir, archived_files, diff_dir):
     run_script(str(rootdir.join('latest.txt')), '-o', str(diff_dir),
                *archived_files)
-    assert len(os.listdir(str(diff_dir))) == 2

[Vasily Kuznetsov, 2018/10/31 14:42:39]

It's a good idea to check how many files were created but we should probably be
consistent between this line and the next. I'd be happy with either approach.

[rhowell, 2018/10/31 19:11:45]

Yeah, it seems more consistent to use the functions available from the LocalPath
object. My main concern here was that, if the diff_dir is empty, these tests
would pass, unless we verify that some files are actually there.

+    assert len(diff_dir.listdir()) == 2
     for file in diff_dir.visit():
         with io.open(str(file), encoding='utf-8') as dst:
             result = dst.read()
         assert '- &ad.vid=$~xmlhttprequest' in result
         assert '+ &ad_channel=\xa3' in result
         assert '! Version: 123' in result
 
 
 def test_diff_no_outfile(rootdir, archived_files):
     os.chdir(str(rootdir))
@@ skipping 14 matching lines @@
 
 def test_wrong_file(rootdir):
     code, err, _ = run_script(str(rootdir.join('base.txt')), 'wrong.txt')
     assert code == 1
     assert 'No such file or directory' in err
 
 
 def test_diff_to_self(rootdir, diff_dir):
     run_script(str(rootdir.join('latest.txt')), '-o', str(diff_dir),
                str(rootdir.join('latest.txt')))
-    assert len(os.listdir(str(diff_dir))) == 1
+    assert len(diff_dir.listdir()) == 1
     for file in diff_dir.visit():
         with io.open(str(file), encoding='utf-8') as dst:
             result = dst.read()
         assert result == '[Adblock Plus Diff]\n'
 
 
 def test_no_version(rootdir, base_no_version):
     code, err, _ = run_script(str(rootdir.join('latest.txt')), '-o',
                               str(diff_dir), *base_no_version)
     assert code == 1
     assert 'Unable to find Version in ' in err
 
 
 def test_write_and_overwrite(rootdir, archived_files, diff_dir):
     test_diff_with_outfile(rootdir, archived_files, diff_dir)
     latest = re.sub(r'&act=ads_', '! ', BASE)
     latest = latest + '&adurl=\n'
     rootdir.join('latest.txt').write_text(latest, encoding='utf8')
     run_script(str(rootdir.join('latest.txt')), '-o', str(diff_dir),
                *archived_files)
-    assert len(os.listdir(str(diff_dir))) == 2
+    assert len(diff_dir.listdir()) == 2
     for file in diff_dir.visit():
         with io.open(str(file), encoding='utf-8') as dst:
             result = dst.read()
         assert '- &act=ads_' in result
         assert '+ &adurl=' in result
         assert '- &ad.vid=$~xmlhttprequest' not in result