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ManageIQ/virtfs-camcorderfs

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VirtFS/CamcorderFS

A pseudo filesystem plugin for the VirtFS infrastructure, that provides the ability to record/playback all filesystem activity that is performed through a given mount point.

Installation

Add this line to your application's Gemfile:

gem 'virtfs-camcorderfs'

And then execute:

$ bundle

Or install it yourself as:

$ gem install virtfs-camcorderfs

Usage

The virtfs-camcorderfs enables the user to mount a given directory of the native filesystem on a virtual mount point within the virtfs infrastructure. Once mounted, all filesystem operations performed through the virtual mount point are recorded or played back as follows:

When a VirtFS::CamcorderFS::FS instance is instantiated, it is passed the loaction of the recording (cassette) file to be used.

  • When the cassette file doesn't exist, the VirtFS::CamcorderFS::FS instance is in record mode. Once mounted, the instance will record all filesystem activity performed through the virtual mount point.

  • When the cassette file does exist VirtFS::CamcorderFS::FS instance is in playback mode. Once mounted, the instance will playback all filesystem activity recorded to the cassette file, bypassing native file system access.

This capability is very useful in developing automated tests that rely on specific aspects of the filesystem that may not be available in the automated test environment (like Travis).

For example, say your tests require access to an NFS share or a block special file. Chances are, the share or special file in question will not be accessible in the Travis environment. The virtfs-camcorderfs plugin provides a solution to this problem similar to the solutions provided by the VCR and camcorder gems. In fact, as the name implies, virtfs-camcorderfs uses the camcorder gem to perform record/playback.

So, the tests are first run in the base test environemnt, the cassette files are recorded and committed along with the tests. When the tests are run within the Travis environemnt, the filesystem interactions are played back from the cassette files, eliminating the need to access the aspects of the filesystem that are not available in the Travis environemnt.

require "virtfs-nativefs-thick"
require "virtfs-camcorderfs"

# Instantiate an instance of the native filesystem.
native_fs = VirtFS::NativeFS::Thick.new

# Mount the native filesystem on root "/"
VirtFS.mount(native_fs, "/")

# Instantiate an instance of CamcorderFS, specifying the cassette file.
cc_fs = VirtFS::CamcorderFS::FS.new(@recording_file)

#
# Mount /dev of the native filesystem on /dev of
# the VirtFS namespace, through CamcorderFS.
#
cc_fs.root = "/dev"
VirtFS.mount(cc_fs, "/dev")

VirtFS.with do
  #
  # Access files under /dev as needed.
  # Interactions are recorded/played back.
  #
end

VirtFS.umount("/dev")

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request

License

The gem is available as open source under the terms of the MIT License.

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