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View supervisor.ex
defmodule Delorean.RankingsShardRepository.RunningShard.Supervisor do
use Supervisor
def start_link(opts) do
Supervisor.start_link(__MODULE__, opts, [])
def start_shard(supervisor, shard_opts) do
Supervisor.start_child(supervisor, shard_opts)
View snapshot_repository_test.exs
defmodule MyApp.SnapshotRepositoryTest do
use ExUnit.Case, async: true
doctest MyApp.SnapshotRepository
alias MyApp.SnapshotRepository.SnapshotOptions
test "queries S3 with a prefix and returns the matched keys" do
options = %SnapshotOptions{ campaign_id: "prod.0.1", backend: "SomeBackend", cycle_type: "week" }
prefix = SnapshotOptions.to_key_prefix(options)
key_1 = "#{prefix}0/2013-03-19T15:04:50Z/mtoken.json.gz"
key_2 = "#{prefix}1/2013-03-19T15:04:50Z/mtoken.json.gz"
View parallel.ex
defmodule Delorean.Parallel do
def map(list, fun) do
|> -> Task.async(fn -> fun.(item) end) end)
View named_doubles.rb
# to get the name, you can use `instance_variable_get`:
tweet = double("Twitter::Tweet")
tweet.instance_variable_get(:@name) # => "Twitter::Tweet"
# that's clearly violating the public API, though. Another way is to pass it as a stub:
tweet = double("Twitter::Tweet", name: "Twitter::Tweet") # => "Twitter::Tweet"
# If you like that approach, you could create a new `named_double`
# helper method:
View sentence_spec.rb
class Sentence
def test(sen)
first = sen[0]
last = sen.split('').last
rest = sen[1..-1]
word_arr = sen.split
word_arr_len = word_arr.length
unless first == first.upcase then
puts "the first letter is not in uppercase"
View stack_overflow_debugger.rb
max_stack_frames = 500
TooManyStackFrames = do |tp|
if caller.size >= max_stack_frames
raise TooManyStackFrames, "Stack has exceeded #{max_stack_frames} frames"
View raise_error_spec.rb
RSpec::Matchers.define :an_exception_caused_by do |cause|
match do |exception|
cause === exception.cause
expect {
"foo".gsub # requires 2 args
rescue ArgumentError
View a_string_including.rb
expect {
expect(the_dbl).to have_received(:expected_method).with(:one).once
}.to raise_error(Expectations::ExpectationNotMetError,
a_string_including("expected: 1 time",
"received: 2 times"))
View Gemfile
# A sample Gemfile
source ""
gem 'rspec'
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