https://www.reddit.com/r/ruby/comments/88jvt9/my_first_contribution_to_the_open_source_ruby_gem/

Most importantly: don't copy code unless you understand what is does.

Read the documentation for Net::HTTP. You're not closing your file descriptors. A long running process may runout of them and error.

JSON.parse(request.body) || {}. Under what circumstances will {} be returned?

Check HTTP response content type before parsing is as JSON. What if HTML is returned?

You should move the request/response lines into get(path), post(path, params) methods.

Create an exception class (or several), catch the various exceptions that can be raised by your HTTP and JSON code, and raise a meaningful exception using your class.

No need to use interpolation when the variable is already a String.

The Travis badge in README.md refers to https://travis-ci.org/degendra/khalti-ruby (repository https://github.com/degendra/khalti-ruby) and not the proper repository here https://github.com/bajratech/khalti-ruby

1. What if the server doesn't respond?
2. What if the API key is invalid?
3. What if the connection times out?
4. What if the server returns a response you don't expect?

Instead of exporting KHALTI_SECRET_KEY, maybe we can create a class to instantiate a khalti object using a KHALTI_SECRET_KEY as a constructor to support multiple khalti accounts.

The token should not be nil or empty.
The amount should be an integer greater than 0.

Update readme to answer the following questions.

1. How to run rspec test?
2. What is the valid token format?

Create an exception class (or several), catch the various exceptions that can be raised by your HTTP and JSON code, and raise a meaningful exception using your class.