If I have a class like this
class Foo < File
# fun stuff
end
and I wanted to test that it is indeed inherits from File, I could write
describe Foo
let(:a_file) { Foo.open('blah.txt') }
it "is a File" do
expect(a_file).to be_a File
end
end
My question is, will the let() take care of closing the file after the example is run? Or do I need to explicitly close the file somewhere.
Or would something like this be better,
it "is a File" do
Foo.open('blah.txt') do |f|
expect(f).to be_a File
end
end
forgetting about the let() entirely?
I looked at using let and closing files for reference, but I'm still unsure.
If you're going to use a_file in just one test, then your second example is good.
it "is a File" do
Foo.open('blah.txt') do |f|
expect(f).to be_a File
end
end
If you'll use a_file multiple times, you could do this:
before do
#file = Foo.open('blah.txt')
end
after do
#file.close
end
it "is a File" do
expect(#file).to be_a File
end
...
Related
All the documentation I've been able to find so far go something like this (when you're in a ruby file):
File.open("textfile.txt", 'w') do |file|
file.write("hello world")
end
No problem there, I can get that to work. But, I can't seem to use methods to do something in an external file. So when I have something like this method:
def today_method
print "-------------------------------"
today = Time.now.strftime("%m/%d/%Y")
puts "\nToday's date: #{today_date}\n"
puts "--------------------------------"
end
And then I have another method like this:
def output_stuff
File.new("textfile.txt", "w+")
File.open("textfile.txt", 'w') do |file|
a = today_method
file.write(a)
end
end
When I call the output_stuff method, nothing happens. The date doesn't show in the textfile. What am I doing wrong??
today_method just puts the date. You want it to return, so put return instead of puts in your date_method.
I am trying to create a test for a FileProcessor that reads from a text file, passes it to another class and then writes output. I made a test file and am able to access but it feels bulky. I'm also going to need to test that it writes the output in a new file and I am not sure how to set this up. I've seen a lot of tutorials but they are be rails centric. My goal is to get rid of writing the path in the test and to clean up the generated output files after each test.
describe FileProcessor do
test_file = File.dirname(__FILE__) + '/fixtures/test_input.txt'
output_file = File.dirname(__FILE__) + '/fixtures/test_output.txt'
subject {FileProcessor.new(test_file, output_file)}
describe '#read_file' do
it 'reads a file' do
expect(subject.read_file).to eq('This is a test.')
end
end
def write_file(str)
File.open("#{output_file}", "w+") { |file| file.write(str) }
end
end
How about using StringIO:
require 'stringio'
class FileProcessor
def initialize(infile, outfile)
#infile = infile
#outfile = outfile
#content = nil
end
def read_file
#content ||= #infile.read
end
def write_file(text)
#outfile.write(text)
end
end
describe FileProcessor do
let(:outfile) { StringIO.new }
subject(:file_processor) do
infile = StringIO.new('This is a test')
FileProcessor.new(infile, outfile)
end
describe '#read_file' do
it "returns correct text" do
expect(file_processor.read_file).to eq("This is a test")
end
end
describe '#write_file' do
it "writes correct text" do
file_processor.write_file("Hello world")
outfile.rewind
expect(outfile.read).to eq("Hello world")
end
end
end
There's not a great way to avoid writing the path of your input file. You could move that into a helper method, but on the other hand having the path in the test has the benefit that someone else (or you six months from now) looking at the code will know immediately where the test data comes from.
As for the output file, the simplest solution is to use Ruby's built-in Tempfile class. Tempfile.new is like File.new, except that it automatically puts the file in /tmp (or wherever your OS's temporary file directory is) and gives it a unique name. This way you don't have to worry about cleaning it up, because the next time you run the test it'll use a file with a different name (and your OS will automatically delete the file). For example:
require 'tempfile'
describe FileProcessor do
let(:test_file_path) { File.dirname(__FILE__) + '/fixtures/test_input.txt' }
let(:output_file) { Tempfile.new('test_output.txt').path }
subject { FileProcessor.new(test_file_path, output_file.path) }
describe '#read_file' do
it 'reads a file' do
expect(subject.read_file).to eq('This is a test.')
end
end
end
Using let (instead of just assigning a local variable) ensures that each example will use its own unique output file. In RSpec you should almost always prefer let.
If you want to get really serious, you could instead use the FakeFS gem, which mocks all of Ruby's built-in file-related classes (File, Pathname, etc.) so you're never writing to your actual filesystem. Here's a quick tutorial on using FakeFS: http://www.bignerdranch.com/blog/fake-it/
I have created a simple class to handle opening, reading, and closing a file. In addition, I would like to run a regex on its contents to find a 4 digit date. However, when I run my code I get the following error:
file_class.rb:17:in `find_date': undefined method `match' for nil:NilClass (NoMethodError)
from file_class.rb:24:in `<main>'
This error only occurs if I run the read_file method before it, which simply puts the file contents. I am not sure why doing so would result in such an error.
Below is my code:
class MyFile
attr_reader :handle
def initialize(filename)
#handle = File.open(filename)
end
def read_file
puts #handle.gets
end
def finished
#handle.close
end
def find_date
matching = #handle.gets.match(/\d{4}/)
puts matching[0]
end
end
f = MyFile.new('text.txt')
f.read_file
f.find_date
f.finished
Thanks for the help.
I'm guessing your file had a single line of contents.
When you call gets on an open file handle, the handle returns the line it is currently looking at and moves its "cursor" down to the next line. After you've read the last line, gets will return nil.
Your class would be better (for a few reasons) if you read the file once and cache the contents, rather than caching the handle and attempting to read several times:
class MyFile
attr_reader :contents
def initialize(filename)
File.open(filename) do |f|
#contents = f.read
end
end
def find_date
matching = #contents.match(/\d{4}/)
puts matching[0]
end
end
This approach is better because:
You only need to read the file once.
You're reading the whole file at once, not one line at a time (File#read instead of File#gets).
Your class has better encapsulation - other code that wants to use it doesn't need to tell your class to read the file, then find a date, then close the file - all of the logic is internal to your class.
You need to write less code - attr_accessor makes contents available to calling code without you needing to write your own methods. This is good because it's quicker to write and, much more importantly, it's clearer to read.
The need here is to read a json file and to make the variables which is done from one class and use them with in another class. What I have so far is
helper.rb
class MAGEINSTALLER_Helper
#note nonrelated items removed
require 'fileutils'
#REFACTOR THIS LATER
def load_settings()
require 'json'
file = File.open("scripts/installer_settings.json", "rb")
contents = file.read
file.close
#note this should be changed for a better content check.. ie:valid json
#so it's a hack for now
if contents.length > 5
begin
parsed = JSON.parse(contents)
rescue SystemCallError
puts "must redo the settings file"
else
puts parsed['bs_mode']
parsed.each do |key, value|
puts "#{key}=>#{value}"
instance_variable_set("#" + key, value) #better way?
end
end
else
puts "must redo the settings file"
end
end
#a method to provide feedback simply
def download(from,to)
puts "completed download for #{from}\n"
end
end
Which is called in a file of Pre_start.rb
class Pre_start
#note nonrelated items removed
def initialize(params=nil)
puts 'World'
mi_h = MAGEINSTALLER_Helper.new
mi_h.load_settings()
bs_MAGEversion=instance_variable_get("#bs_MAGEversion") #doesn't seem to work
file="www/depo/newfile-#{bs_MAGEversion}.tar.gz"
if !File.exist?(file)
mi_h.download("http://www.dom.com/#{bs_MAGEversion}/file-#{bs_MAGEversion}.tar.gz",file)
else
puts "mage package exists"
end
end
end
the josn file is valid json and is a simple object (note there is more just showing the relevant)
{
"bs_mode":"lite",
"bs_MAGEversion":"1.8.0.0"
}
The reason I need to have a json settings file is that I will need to pull settings from a bash script and later a php script. This file is the common thread that is used to pass settings each share and need to match.
Right now I end up with an empty string for the value.
The instance_variable_setis creating the variable inside MAGEINSTALLER_Helper class. That's the reason why you can't access these variables.
You can refactor it into a module, like this:
require 'fileutils'
require 'json'
module MAGEINSTALLER_Helper
#note nonrelated items removed
#REFACTOR THIS LATER
def load_settings()
content = begin
JSON.load_file('scripts/installer_settings.json')
rescue
puts 'must redo the settings file'
{} # return an empty Hash object
end
parsed.each {|key, value| instance_variable_set("##{key}", value)}
end
#a method to provide feedback simply
def download(from,to)
puts "completed download for #{from}\n"
end
end
class PreStart
include MAGEINSTALLER_Helper
#note nonrelated items removed
def initialize(params=nil)
puts 'World'
load_settings # The method is available inside the class
file="www/depo/newfile-#{#bs_MAGEversion}.tar.gz"
if !File.exist?(file)
download("http://www.dom.com/#{#bs_MAGEversion}/file-#{#bs_MAGEversion}.tar.gz",file)
else
puts "mage package exists"
end
end
end
I refactored a little bit to more Rubish style.
On this line:
bs_MAGEversion=instance_variable_get("#bs_MAGEversion") #doesn't seem to work
instance_variable_get isn't retrieving from the mi_h Object, which is where your value is stored. The way you've used it, that line is equivalent to:
bs_MAGEversion=#bs_MAGEversion
Changing it to mi_h.instance_variable_get would work. It would also be painfully ugly ruby. But I sense that's not quite what you're after. If I read you correctly, you want this line:
mi_h.load_settings()
to populate #bs_MAGEversion and #bs_mode in your Pre_start object. Ruby doesn't quite work that way. The closest thing to what you're looking for here would probably be a mixin, as described here:
http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_modules.html
We do something similar to this all the time in code at work. The problem, and solution, is proper use of variables and scoping in the main level of your code. We use YAML, you're using JSON, but the idea is the same.
Typically we define a constant, like CONFIG, which we load the YAML into, in our main code, and which is then available in all the code we require. For you, using JSON instead:
require 'json'
require_relative 'helper'
CONFIG = JSON.load_file('path/to/json')
At this point CONFIG would be available to the top-level code and in "helper.rb" code.
As an alternate way of doing it, just load your JSON in either file. The load-time is negligible and it'll still be the same data.
Since the JSON data should be static for the run-time of the program, it's OK to use it in a CONSTANT. Storing it in an instance variable only makes sense if the data would vary from instance to instance of the code, which makes no sense when you're loading data from a JSON or YAML-type file.
Also, notice that I'm using a method from the JSON class. Don't go through the rigamarole you're using to try to copy the JSON into the instance variable.
Stripping your code down as an example:
require 'fileutils'
require 'json'
CONTENTS = JSON.load_file('scripts/installer_settings.json')
class MAGEINSTALLER_Helper
def download(from,to)
puts "completed download for #{from}\n"
end
end
class Pre_start
def initialize(params=nil)
file = "www/depo/newfile-#{ CONFIG['bs_MAGEversion'] }.tar.gz"
if !File.exist?(file)
mi_h.download("http://www.dom.com/#{ CONFIG['bs_MAGEversion'] }/file-#{ CONFIG['bs_MAGEversion'] }.tar.gz", file)
else
puts "mage package exists"
end
end
end
CONFIG can be initialized/loaded in either file, just do it from the top-level before you need to access the contents.
Remember, Ruby starts executing it at the top of the first file and reads downward. Code that is outside of def, class and module blocks gets executed as it's encountered, so the CONFIG initialization will happen as soon as Ruby sees that code. If that happens before you start calling your methods and creating instances of classes then your code will be happy.
I want to do is run ruby sayhello.rb on the command line, then receive Hello from Rspec.
I've got that with this:
class Hello
def speak
puts 'Hello from RSpec'
end
end
hi = Hello.new #brings my object into existence
hi.speak
Now I want to write a test in rspec to check that the command line output is in fact "Hello from RSpec"
and not "I like Unix"
NOT WORKING. I currently have this in my sayhello_spec.rb file
require_relative 'sayhello.rb' #points to file so I can 'see' it
describe "sayhello.rb" do
it "should say 'Hello from Rspec' when ran" do
STDOUT.should_receive(:puts).with('Hello from RSpec')
end
end
Can someone point me in the right direction please?
Here's a pretty good way to do this. Copied from the hirb test_helper source:
def capture_stdout(&block)
original_stdout = $stdout
$stdout = fake = StringIO.new
begin
yield
ensure
$stdout = original_stdout
end
fake.string
end
Use like this:
output = capture_stdout { Hello.new.speak }
output.should == "Hello from RSpec\n"
The quietly command is probably what you want (cooked into ActiveSupport, see docs at api.rubyonrails.org). This snippet of RSpec code below shows how to ensure there is no output on stderr while simultaneously silencing stdout.
quietly do # silence everything
commands.each do |c|
content = capture(:stderr) { # capture anything sent to :stderr
MyGem::Cli.start(c)
}
expect(content).to be_empty, "#{c.inspect} had output on stderr: #{content}"
end
end
So you don't have to change your main ruby code I just found out you can do something like this:
def my_meth
print 'Entering my method'
p 5 * 50
puts 'Second inside message'
end
describe '#my_meth' do
it 'puts a 2nd message to the console' do
expect{my_meth}.to output(/Second inside message/).to_stdout
end
end
When checking for a desired output text I used it inside / / like a Regexp because after many many maaany tests and looking around, the STDOUT is everything that is outputted so I found it to be better to use Regex so you could check the whole STDOUT for the exact text that you want.
Like I put it, it works in the terminal just perfect.
//Just had to share this, it took me days to figure it out.
it "should say 'Hello from Rspec' when run" do
output = `ruby sayhello.rb`
output.should == 'Hello from RSpec'
end