Add file permissions to filesystem_mock

third_party/WebKit/Tools/Scripts/webkitpy/common/system/filesystem_mock.py

 # Copyright (C) 2009 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #    * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #    * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 31 matching lines @@
     def __init__(self, files=None, dirs=None, cwd='/'):
         """Initializes a "mock" filesystem that can be used to completely
         stub out a filesystem.
 
         Args:
             files: a dict of filenames -> file contents. A file contents
                 value of None is used to indicate that the file should
                 not exist.
         """
         self.files = files or {}
+        self.perms = {}

[qyearsley, 2016/06/14 21:47:02]

Although it's nice that `perms` is the same length as `files`, I feel that it is
often nice to avoid abbreviations because:
 (1) if there are a lot of abbreviations in the code, one has to think about
whether the name is "perms" or "permissions", "cmds" or "commands", etc.
 (2) un-abbreviated variable names are usually less ambiguous.

That said, there are lots of other abbreviations in this code now, and perms is
also fine.

         self.written_files = {}
         self.last_tmpdir = None
         self.current_tmpno = 0
         self.cwd = cwd
         self.dirs = set(dirs or [])
         self.dirs.add(cwd)
         for f in self.files:
+            self.perms[f] = '-rwxrwxrwx'
+        for f in self.files:
             d = self.dirname(f)
             while not d in self.dirs:
                 self.dirs.add(d)
                 d = self.dirname(d)
-
     def clear_written_files(self):
         # This function can be used to track what is written between steps in a test.
         self.written_files = {}
 
     def _raise_not_found(self, path):
         raise IOError(errno.ENOENT, path, os.strerror(errno.ENOENT))
 
     def _split(self, path):
         # This is not quite a full implementation of os.path.split
         # http://docs.python.org/library/os.path.html#os.path.split
         if self.sep in path:
             return path.rsplit(self.sep, 1)
         return ('', path)
 
+    def chmod(self, file_path, mode):
+        # Incomplete implementation of os.chmod
+        # only supports number modes
+        mode_list = []
+        for i in range(0, 3):
+            temp = mode % 10
+            mode_list.append(temp)
+            mode /= 10
+            temp = i
+        temp_perms = '-'
+        temp_perms += self.chmod_options(mode_list[0])
+        temp_perms += self.chmod_options(mode_list[1])
+        temp_perms += self.chmod_options(mode_list[2])
+        self.perms[file_path] = temp_perms

[qyearsley, 2016/06/14 21:47:02]

List comprehensions (and related expressions) are awesome and allow you to
express some things more concisely in Python. For example:

mode_digits = [int(d) for d in mode]
self.perms[file_path] = '-' + ''.join(self.chmod_options(d) for d in
mode_digits)

+
+    def chmod_options(self, arg):

[qyearsley, 2016/06/14 21:47:02]

1. The variable name `arg` could perhaps be improved.

A recent episode of TotT
(https://big.corp.google.com/~jmcmaster/testing/2016/06/episode-431-identifier...)
said that names should be two things: clear (know what it refers to) and precise
(know what it does not refer to). In this case, the name "arg" doesn't tell you
much about what it is.

Do you think `octal_digit` or `mode_digit` might make sense? Maybe there's
another better name?

2. The function name chmod_options doesn't tell me much about what this function
does -- maybe mode_digit_to_string? But that's a bit too long.

3. Since this function doesn't use `self`, you can put a `@staticmethod`
decorator above the def line, and remove the self argument.

+        switcher = {
+            0: '---',
+            1: '--x',
+            2: '-w-',
+            3: '-wx',
+            4: 'r--',
+            5: 'r-x',
+            6: 'rw-',
+            7: 'rwx',
+        }
+        return switcher.get(arg, None)

[qyearsley, 2016/06/14 21:47:02]

None is the default default for dict.get, so this line could be changed to:
`return switcher.get(arg)`

+
     def abspath(self, path):
         if os.path.isabs(path):
             return self.normpath(path)
         return self.abspath(self.join(self.cwd, path))
 
     def realpath(self, path):
         return self.abspath(path)
 
     def basename(self, path):
         return self._split(path)[1]
@@ skipping 402 matching lines @@
         return self.data.readline(length)
 
     def __iter__(self):
         return self.data.__iter__()
 
     def next(self):
         return self.data.next()
 
     def seek(self, offset, whence=os.SEEK_SET):
         self.data.seek(offset, whence)