How to test Redis Lock via Rspec?

[Saurav Kothari]

We have a Lockable concern that allows for locks via Redis

module Lockable
  extend ActiveSupport::Concern

  def redis_lock(key, options = {})
    Redis::Lock.new(
      key,
      expiration: options[:expiration] || 15,
      timeout: options[:timeout] || 0.1
    ).lock { yield if block_given? }
  end
end

We use this in a Controller method to ensure concurrent requests are handled correctly.

def create
  redis_lock(<generated_key>, timeout: 15) do
    # perform_operation
  end

  render json: <data>, status: :ok
end

When testing this action, I want to test that the correct generated_key is being sent to Redis to initiate a lock.

I set up an expect for the Redis::Lock but that returns false always presumably because the request to create is sent mid request and not at the end of it.

expect(Redis::Lock).to receive(:create).once

---

Since the lock is cleared at the end of the method call, I cannot check for the key in redis as a test.

This answer recommends setting up a fake class that matches the structure of Lockable to emulate the same behaviour but how do I write a test for it? The method we have does not return any value to verify.

<SO link to the same question>

[Hassan Schroeder]

On Thu, Aug 9, 2018 at 3:32 AM, Saurav Kothari <sauravk...@gmail.com> wrote:

> We have a Lockable concern that allows for locks via Redis

> When testing this action, I want to test that the correct generated_key is
> being sent to Redis to initiate a lock.

What is the definition of "correct" here? Wouldn't it be easier to just
test the "correctness" of the producer of that key?

--
Hassan Schroeder ------------------------ hassan.s...@gmail.com
twitter: @hassan
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