RSpec spies work differently on two different classes - ruby

Question

I have a class Uploader which takes a file and uploads it to S3. I'm trying to test that #s3 is actually receiving a file body when upload_file is called. When I test that File is getting messages sent, the test passes. However, trying to spy on Aws::S3::Client does not work.
class Uploader
def initialize(tmp_dir_name, bucket)
#base_tmp_dir = tmp_dir_name
#s3 = Aws::S3::Client.new(region: 'us-east-1')
#bucket = bucket
#uploaded_assets = []
end
def upload_file(key, file_path)
file = File.new(file_path)
#s3.put_object(bucket: #bucket, key: key.to_s, body: file.read)
end
end
RSpec.describe Uploader do
let(:bucket) { 'test_bucket' }
let(:base_temp_dir) { 'test_temp_dir' }
let(:uploader) { Uploader.new(base_temp_dir, bucket) }
describe "#upload_file" do
let(:file) { double('file') }
before { allow(File).to receive(:new) { file } }
before { allow(file).to receive(:read).and_return('text') }
before { allow(Aws::S3::Client).to receive(:put_object) }
it "uses one file" do
uploader.upload_file('test_key', 'file_path')
expect(File).to have_received(:new).with('file_path')
end
it "sends data to s3" do
uploader.upload_file('test_key', 'file_path')
expect(Aws::S3::Client).to have_received(:put_object)
end
end
end

Answer 1

I ended up mocking out s3 for this particular test.
it "sends data to s3" do
test_key = 'test_key'
bucket = 'test_bucket'
fake_s3 = instance_double(Aws::S3::Client)
allow(Aws::S3::Client).to receive(:new).and_return(fake_s3)
allow(fake_s3).to receive(:put_object)
uploader.upload_file(test_key, 'file_path', record=true)
expect(fake_s3).to have_received(:put_object).with(
{bucket: bucket, key: test_key, body: 'text'})
end