Rspec Ruby on Rails Test File System in model - ruby-on-rails

Question

I have a model that has a method that looks through the filesystem starting at a particular location for files that match a particular regex. This is executed in an after_save callback. I'm not sure how to test this using Rspec and FactoryGirl. I'm not sure how to use something like FakeFS with this because the method is in the model, not the test or the controller. I specify the location to start in my FactoryGirl factory, so I could change that to a fake directory created by the test in a set up clause? I could mock the directory? I think there are probably several different ways I could do this, but which makes the most sense?
Thanks!
def ensure_files_up_to_date
files = find_assembly_files
add_files = check_add_assembly_files(files)
errors = add_assembly_files(add_files)
if errors.size > 0 then
return errors
end
update_files = check_update_assembly_files(files)
errors = update_assembly_files(update_files)
if errors.size > 0 then
return errors
else
return []
end
end
def find_assembly_files
start_dir = self.location
files = Hash.new
if ! File.directory? start_dir then
errors.add(:location, "Directory #{start_dir} does not exist on the system.")
abort("Directory #{start_dir} does not exist on the system for #{self.inspect}")
end
Find.find(start_dir) do |path|
filename = File.basename(path).split("/").last
FILE_TYPES.each { |filepart, filehash|
type = filehash["type"]
vendor = filehash["vendor"]
if filename.match(filepart) then
files[type] = Hash.new
files[type]["path"] = path
files[type]["vendor"] = vendor
end
}
end
return files
end
def check_add_assembly_files(files=self.find_assembly_files)
add = Hash.new
files.each do |file_type, file_hash|
# returns an array
file_path = file_hash["path"]
file_vendor = file_hash["vendor"]
filename = File.basename(file_path)
af = AssemblyFile.where(:name => filename)
if af.size == 0 then
add[file_path] = Hash.new
add[file_path]["type"] = file_type
add[file_path]["vendor"] = file_vendor
end
end
if add.size == 0 then
logger.error("check_add_assembly_files did not find any files to add")
return []
end
return add
end
def check_update_assembly_files(files=self.find_assembly_files)
update = Hash.new
files.each do |file_type, file_hash|
file_path = file_hash["path"]
file_vendor = file_hash["vendor"]
# returns an array
filename = File.basename(file_path)
af = AssemblyFile.find_by_name(filename)
if !af.nil? then
if af.location != file_path or af.file_type != file_type then
update[af.id] = Hash.new
update[af.id]['path'] = file_path
update[af.id]['type'] = file_type
update[af.id]['vendor'] = file_vendor
end
end
end
return update
end
def add_assembly_files(files=self.check_add_assembly_files)
if files.size == 0 then
logger.error("add_assembly_files didn't get any results from check_add_assembly_files")
return []
end
asm_file_errors = Array.new
files.each do |file_path, file_hash|
file_type = file_hash["type"]
file_vendor = file_hash["vendor"]
logger.debug "file type is #{file_type} and path is #{file_path}"
logger.debug FileType.find_by_type_name(file_type)
file_type_id = FileType.find_by_type_name(file_type).id
header = file_header(file_path, file_vendor)
if file_vendor == "TBA" then
check = check_tba_header(header, file_type, file_path)
software = header[TBA_SOFTWARE_PROGRAM]
software_version = header[TBA_SOFTWARE_VERSION]
elsif file_vendor == "TBB" then
check = check_tbb_header(header, file_type, file_path)
if file_type == "TBB-ANNOTATION" then
software = header[TBB_SOURCE]
else
software = "Unified"
end
software_version = "UNKNOWN"
end
if check == 0 then
logger.error("skipping file #{file_path} because it contains incorrect values for this filetype")
asm_file_errors.push("#{file_path} cannot be added to assembly because it contains incorrect values for this filetype")
next
end
if file_vendor == "TBA" then
xml = header.to_xml(:root => "assembly-file")
elsif file_vendor == "TBB" then
xml = header.to_xml
else
xml = ''
end
filename = File.basename(file_path)
if filename.match(/~$/) then
logger.error("Skipping a file with a tilda when adding assembly files. filename #{filename}")
next
end
assembly_file = AssemblyFile.new(
:assembly_id => self.id,
:file_type_id => file_type_id,
:name => filename,
:location => file_path,
:file_date => creation_time(file_path),
:software => software,
:software_version => software_version,
:current => 1,
:metadata => xml
)
assembly_file.save! # exclamation point forces it to raise an error if the save fails
end # end files.each
return asm_file_errors
end

Answer 1

Quick answer: you can stub out model methods like any others. Either stub a specific instance of a model, and then stub find or whatever to return that, or stub out any_instance to if you don't want to worry about which model is involved. Something like:
it "does something" do
foo = Foo.create! some_attributes
foo.should_receive(:some_method).and_return(whatever)
Foo.stub(:find).and_return(foo)
end
The real answer is that your code is too complicated to test effectively. Your models should not even know that a filesystem exists. That behavior should be encapsulated in other classes, which you can test independently. Your model's after_save can then just call a single method on that class, and testing whether or not that single method gets called will be a lot easier.
Your methods are also very difficult to test, because they are trying to do too much. All that conditional logic and external dependencies means you'll have to do a whole lot of mocking to get to the various bits you might want to test.
This is a big topic and a good answer is well beyond the scope of this answer. Start with the Wikipedia article on SOLID and read from there for some of the reasoning behind separating concerns into individual classes and using tiny, composed methods. To give you a ballpark idea, a method with more than one branch or more than 10 lines of code is too big; a class that is more than about 100 lines of code is too big.