Add net-ssh gem version to doctor:gems output (#1708)

Closes #1705

CHANGELOG.md

@@ -13,6 +13,7 @@ https://github.com/capistrano/capistrano/compare/v3.5.0...HEAD
   * Change git wrapper path to work better with multiple users (@thickpaddy)
   * Make name of current directory configurable via configuration variable `:current_directory` (@websi)
   * `doctor` no longer erroneously warns that `:git_strategy` and other SCM options are "unrecognized" (@shanesaww)
+  * Add `net-ssh` gem version to `doctor:gems` output (@lebedev-yury)
 
 ## `3.5.0`
 

lib/capistrano/doctor/gems_doctor.rb

@@ -34,7 +34,7 @@ module Capistrano
       end
 
       def core_gem_names
-        %w(capistrano airbrussh rake sshkit) & Gem.loaded_specs.keys
+        %w(capistrano airbrussh rake sshkit net-ssh) & Gem.loaded_specs.keys
       end
 
       def plugin_gem_names

spec/lib/capistrano/doctor/gems_doctor_spec.rb

@@ -2,6 +2,7 @@ require "spec_helper"
 require "capistrano/doctor/gems_doctor"
 require "airbrussh/version"
 require "sshkit/version"
+require "net/ssh/version"
 
 module Capistrano
   module Doctor
@@ -32,6 +33,11 @@ module Capistrano
           output(/airbrussh\s+#{Regexp.quote(Airbrussh::VERSION)}/).to_stdout
       end
 
+      it "prints the net-ssh version" do
+        expect { doc.call }.to\
+          output(/net-ssh\s+#{Regexp.quote(Net::SSH::Version::STRING)}/).to_stdout
+      end
+
       it "warns that new version is available" do
         Gem.stubs(:latest_version_for).returns(Gem::Version.new("99.0.0"))
         expect { doc.call }.to output(/\(update available\)/).to_stdout