Elasticsearch works fine in localhost, but gives connection error while testing

Question

I'm new to Elasticsearch and Docker. I'm getting search results with my application, But when I run test against the same , I'm getting connection error like this

cannot assign requested address - cannot assign requested address - connect(2) for "localhost" port 9200 (localhost:9200)

I'm using chewy gem of ruby on rails to implement Elasticsearch

here is the sample code of search

result = TestIndex::Test
                     .filter(match: { test_id: testid })
                     .query(something
                      })
                     .highlight({something
                                  }
                                })
                   .paginate(page: page, per_page: page_size).as_json

I'm testing using Rspec Note that search is working fine in application. This error occurs when running the test file