1 files changed, 16 insertions, 0 deletions
diff --git a/spec/install/gemfile_spec.rb b/spec/install/gemfile_spec.rb
index 9262dcc92d..d1b1f1e6b8 100644
--- a/spec/install/gemfile_spec.rb
+++ b/spec/install/gemfile_spec.rb
@@ -66,6 +66,22 @@ RSpec.describe "bundle install" do
     end
   end
 
+  context "with prefer_gems_rb set" do
+    before { bundle! "config prefer_gems_rb true" }
+
+    it "prefers gems.rb to Gemfile" do
+      create_file("gems.rb", "gem 'bundler'")
+      create_file("Gemfile", "raise 'wrong Gemfile!'")
+
+      bundle! :install
+
+      expect(bundled_app("gems.rb")).to be_file
+      expect(bundled_app("Gemfile.lock")).not_to be_file
+
+      expect(the_bundle).to include_gem "bundler #{Bundler::VERSION}"
+    end
+  end
+
   context "with engine specified in symbol" do
     it "does not raise any error parsing Gemfile" do
       simulate_ruby_version "2.3.0" do