module MemFs

Provides a clean way to interact with a fake file system.

@example Calling activate with a block.

MemFs.activate do
  Dir.mkdir '/hello_world'
  # /hello_world exists here, in memory
end
# /hello_world doesn't exist and has never been on the real FS

@example Calling activate! and deactivate!.

MemFs.activate!
  # The fake file system is running here
MemFs.deactivate!
# Everything back to normal

Constants

OriginalDir: Keeps track of the original Ruby Dir class.
OriginalFile: Keeps track of the original Ruby File class.
OriginalIO: Keeps track of the original Ruby IO class.
VERSION

Public Class Methods

activate() { || ... } click to toggle source

Calls the given block with MemFs activated.

The advantage of using {#activate} against {#activate!} is that, in case an exception occurs, MemFs is deactivated.

@yield with no argument.

@example

MemFs.activate do
  Dir.mkdir '/hello_world'
  # /hello_world exists here, in memory
end
# /hello_world doesn't exist and has never been on the real FS

@example Exception in activate block.

MemFs.activate do
  raise "Some Error"
end
# Still back to the original Ruby classes

@return nothing.

# File lib/memfs.rb, line 62
def activate
  activate!
  yield
ensure
  deactivate!
end

activate!(clear: true) click to toggle source

Activates the fake file system.

@note Don’t forget to call {#deactivate!} to disable the fake file system,

you may have some issues in your scripts or tests otherwise.

@example

MemFs.activate!
Dir.mkdir '/hello_world'
# /hello_world exists here, in memory
MemFs.deactivate!
# /hello_world doesn't exist and has never been on the real FS

@see deactivate! @return nothing.

# File lib/memfs.rb, line 84
def activate!(clear: true)
  Object.class_eval do
    remove_const :Dir
    remove_const :File
    remove_const :IO

    const_set :Dir, MemFs::Dir
    const_set :IO, MemFs::IO
    const_set :File, MemFs::File
  end

  MemFs::FileSystem.instance.clear! if clear
end

deactivate!() click to toggle source

Deactivates the fake file system.

@note This method should always be called when using activate!

@see activate! @return nothing.

# File lib/memfs.rb, line 105
def deactivate!
  Object.class_eval do
    remove_const :Dir
    remove_const :File
    remove_const :IO

    const_set :Dir, MemFs::OriginalDir
    const_set :IO, MemFs::OriginalIO
    const_set :File, MemFs::OriginalFile
  end
end

halt() { || ... } click to toggle source

Switches back to the original file system, calls the given block (if any), and switches back afterwards.

If a block is given, all file & dir operations (like reading dir contents or requiring files) will operate on the original fs.

@example

MemFs.halt do
  puts Dir.getwd
end

@return nothing

# File lib/memfs.rb, line 129
def halt
  deactivate!

  yield if block_given?
ensure
  activate!(clear: false)
end

touch(*paths) click to toggle source

Creates a file and all its parent directories.

@param path: The path of the file to create.

@return nothing.

# File lib/memfs.rb, line 143
def touch(*paths)
  if ::File != MemFs::File
    fail 'Always call MemFs.touch inside a MemFs active context.'
  end

  paths.each do |path|
    FileUtils.mkdir_p File.dirname(path)
    FileUtils.touch path
  end
end

windows?() click to toggle source

# File lib/memfs.rb, line 32
def self.windows?
  /mswin|bccwin|mingw/ =~ RUBY_PLATFORM
end

Private Instance Methods

activate() { || ... } click to toggle source

Calls the given block with MemFs activated.

The advantage of using {#activate} against {#activate!} is that, in case an exception occurs, MemFs is deactivated.

@yield with no argument.

@example

MemFs.activate do
  Dir.mkdir '/hello_world'
  # /hello_world exists here, in memory
end
# /hello_world doesn't exist and has never been on the real FS

@example Exception in activate block.

MemFs.activate do
  raise "Some Error"
end
# Still back to the original Ruby classes

@return nothing.

# File lib/memfs.rb, line 62
def activate
  activate!
  yield
ensure
  deactivate!
end

activate!(clear: true) click to toggle source

Activates the fake file system.

@note Don’t forget to call {#deactivate!} to disable the fake file system,

you may have some issues in your scripts or tests otherwise.

@example

MemFs.activate!
Dir.mkdir '/hello_world'
# /hello_world exists here, in memory
MemFs.deactivate!
# /hello_world doesn't exist and has never been on the real FS

@see deactivate! @return nothing.

# File lib/memfs.rb, line 84
def activate!(clear: true)
  Object.class_eval do
    remove_const :Dir
    remove_const :File
    remove_const :IO

    const_set :Dir, MemFs::Dir
    const_set :IO, MemFs::IO
    const_set :File, MemFs::File
  end

  MemFs::FileSystem.instance.clear! if clear
end

deactivate!() click to toggle source

Deactivates the fake file system.

@note This method should always be called when using activate!

@see activate! @return nothing.

# File lib/memfs.rb, line 105
def deactivate!
  Object.class_eval do
    remove_const :Dir
    remove_const :File
    remove_const :IO

    const_set :Dir, MemFs::OriginalDir
    const_set :IO, MemFs::OriginalIO
    const_set :File, MemFs::OriginalFile
  end
end

halt() { || ... } click to toggle source

Switches back to the original file system, calls the given block (if any), and switches back afterwards.

If a block is given, all file & dir operations (like reading dir contents or requiring files) will operate on the original fs.

@example

MemFs.halt do
  puts Dir.getwd
end

@return nothing

# File lib/memfs.rb, line 129
def halt
  deactivate!

  yield if block_given?
ensure
  activate!(clear: false)
end

touch(*paths) click to toggle source

Creates a file and all its parent directories.

@param path: The path of the file to create.

@return nothing.

# File lib/memfs.rb, line 143
def touch(*paths)
  if ::File != MemFs::File
    fail 'Always call MemFs.touch inside a MemFs active context.'
  end

  paths.each do |path|
    FileUtils.mkdir_p File.dirname(path)
    FileUtils.touch path
  end
end