Add a new buildbot-tool generator for master configs

scripts/common/fake_filesystem.py

Index: scripts/common/fake_filesystem.py
diff --git a/scripts/common/fake_filesystem.py b/scripts/common/fake_filesystem.py
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+++ b/scripts/common/fake_filesystem.py
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+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+
+
+class FakeFilesystem(object):
+  """A fake implementation of the Filesystem class in filesystem.py.
+
+  This is a stripped-down version of the FakeHost class provided in the
+  TYP (Test Your Project) framework: https://github.com/dpranke/typ.
+  """
+  def __init__(self, files=None, cwd='/'):
+    self.sep = '/'
+    self.cwd = cwd
+    self.files = files or {}
+    self.dirs = set(self.dirname(f) for f in self.files)
+
+  def abspath(self, relpath):
+    if relpath.startswith(self.sep):
+      return relpath
+    return self.join(self.cwd, relpath)
+
+  def basename(self, path):
+    return path.split(self.sep)[-1]
+
+  def dirname(self, path):
+    return self.sep.join(path.split(self.sep)[:-1])
+
+  def exists(self, *comps):
+    path = self.abspath(*comps)
+    return ((path in self.files and self.files[path] is not None) or
+             path in self.dirs)
+
+  def join(self, *comps):
+    p = ''
+    for c in comps:
+      if c in ('', '.'):
+        continue
+      elif c.startswith(self.sep):
+        p = c
+      elif p:
+        p += self.sep + c
+      else:
+        p = c
+
+    # Handle ./
+    p = p.replace('/./', self.sep)
+
+    # Handle ../
+    while '../' in p:
+      comps = p.split(self.sep)
+      idx = comps.index('..')
+      comps = comps[:idx-1] + comps[idx+1:]
+      p = self.sep.join(comps)
+    return p
+
+  def listfiles(self, path):
+    return [filepath.replace(path + self.sep, '') for filepath in self.files
+            if (self.dirname(filepath) == path and
+                not self.basename(filepath).startswith('.'))]
+
+  def read_text_file(self, path):
+    return self.files[self.abspath(path)]
+
+  def relpath(self, path, start='.'):
+    full_path = self.abspath(path)
+    full_start = self.abspath(start)
+
+    # TODO: handle cases where path is not directly under start.
+    assert full_start in full_path
+    return full_path[len(full_start) + 1:]
+
+  def write_text_file(self, path, contents):
+    self.files[self.abspath(path)] = contents