Add file permissions to filesystem_mock

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

Index: third_party/WebKit/Tools/Scripts/webkitpy/common/system/filesystem_mock.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/common/system/filesystem_mock.py b/third_party/WebKit/Tools/Scripts/webkitpy/common/system/filesystem_mock.py
index 44c7d8043d507f9dad2c683232b2e28ea01e5dd7..d457d2c4f91b93282a643318b506fa9ad2b1066a 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/common/system/filesystem_mock.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/common/system/filesystem_mock.py
@@ -49,6 +49,7 @@ class MockFileSystem(object):
                 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
@@ -56,11 +57,12 @@ class MockFileSystem(object):
         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 = {}
@@ -75,6 +77,34 @@ class MockFileSystem(object):
             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)