Rspec: No such file or directory # rb_sysopen - - ruby

Question

I'm trying to write a simple test for a ruby script that uses gets and I'm experiencing some weird behavior.
When I run the test with rspec it passes fine, but as soon as I run rspec with any flags, like rspec -f json or rspec -O rand the test will fail and give me No such file or directory # rb_sysopen - -O, where -O is whatever the flag that was run.
Stranger still is that if I run rspec and specify the test file like rspec spec/gets_spec.rb, I get a completely different error:
Failure/Error: expect { require_relative '../gets' }.to output("Hello, Lena!\n").to_stdout
expected block to output "Hello, Lena!\n" to stdout, but output "Hello, Describe \"gets.rb\" do!\n"
Diff:
## -1,2 +1,2 ##
-Hello, Lena!
+Hello, Describe "gets.rb" do!
# ./spec/gets_spec.rb:14:in `block (2 levels) in <top (required)>'
I'm having trouble figuring out the right way to write my test so that this doesn't happen but I'm not sure what part of my code needs to change.
I'm using ruby 2.6.3
I learned about testing input from this question
The script, gets.rb, looks like
puts "Hello, #{gets.chomp.capitalize}!"
My test looks like
describe "gets.rb" do
before do
$stdin = StringIO.new("lena")
end
after do
$stdin = STDIN
end
it "should output 'Hello, name!'" , points: 1 do
allow($stdin).to receive(:gets).and_return("lena")
expect { require_relative "../gets" }.to output("Hello, Lena!\n").to_stdout
end
end
Here's the full failure message:
Failures:
1) gets.rb should output 'Hello, name!'
Failure/Error: expect { require_relative '../gets' }.to output("Hello, Lena!\n").to_stdout
Errno::ENOENT:
No such file or directory # rb_sysopen - -O
#./gets.rb:1:in `gets'
# ./gets.rb:1:in `gets'
# ./gets.rb:1:in `<top (required)>'
# ./spec/gets_spec.rb:14:in `require_relative'
# ./spec/gets_spec.rb:14:in `block (3 levels) in <top (required)>'
# ./spec/gets_spec.rb:14:in `block (2 levels) in <top (required)>'

Answer 1

You can try to use a little different approach:
describe "gets.rb" do
it "should output 'Hello, name!'" do
allow_any_instance_of(Object).to receive(:gets).and_return("lena")
expect { require_relative "../gets.rb" }.to output("Hello, Lena!\n").to_stdout
end
end
allow_any_instance_of I took from https://makandracards.com/makandra/41096-stubbing-terminal-user-input-in-rspec
Reading user input in console applications is usually done using Kernel#gets.
The page suggests to use Object.any_instance.stub(gets: 'user input') but it's deprecated syntax already and I've updated it.