add exit status assertions to execution spec

spec/datadog/core/environment/execution_spec.rb

@@ -59,10 +59,11 @@
       context 'when in an IRB session' do
         it 'returns true' do
           # Ruby 2.6 does not have irb by default in a bundle, but has it outside of it.
-          _, err, = Bundler.with_unbundled_env do
+          _, err, status = Bundler.with_unbundled_env do
             Open3.capture3('irb', '--noprompt', '--noverbose', '--noecho', stdin_data: repl_script)
           end
           expect(err).to end_with('ACTUAL:true')
+          expect(status.exitstatus).to eq(0)
         end
       end
 
@@ -203,11 +204,12 @@ def test_it_does_something_useful
               # Add our script to `env.rb`, which is always run before any feature is executed.
               File.write('features/support/env.rb', repl_script)
 
-              _, err, = Bundler.with_unbundled_env do
+              _, err, status = Bundler.with_unbundled_env do
                 Open3.capture3('ruby', stdin_data: script)
               end
 
               expect(err).to include('ACTUAL:true')
+              expect(status.exitstatus).to eq(0)
             end
           end
         end
@@ -270,7 +272,7 @@ def test_it_does_something_useful
 
     context 'when given WebMock', skip: Gem::Version.new(Bundler::VERSION) < Gem::Version.new('2') do
       it do
-        out, = Bundler.with_unbundled_env do
+        out, err, status = Bundler.with_unbundled_env do
           Open3.capture3('ruby', stdin_data: <<-RUBY
             require 'bundler/inline'
 
@@ -292,6 +294,7 @@ def test_it_does_something_useful
         end
 
         expect(out).to end_with('ACTUAL:true')
+        expect(status.exitstatus).to eq(0)
       end
     end
   end