add a failing spec for not-found gems

This is a kind of weird and specific situation:

If, and only if, some version of a gem is installed into system gems
(e.g. rack 1.0), then trying to resolve a different version of that gem
from a specific remote source (e.g. rack 2.0.1.1.forked) will fail, even
though that gem is in fact available from that soure. Uninstalling the
unrelated version of rack from system gems completely solves this
problem. Alternately, running `bundle update rack` instead of `bundle
install` also completely solves this problem.

From this I speculate that we are unfairly withholding the rack
2.0.1.1.forked spec from the resolver, even though it was provided by
the source.

1 files changed, 71 insertions, 0 deletions

diff --git a/spec/install/gemfile/sources_spec.rb b/spec/install/gemfile/sources_spec.rb
index fd11c3feab..aae5953f31 100644
--- a/spec/install/gemfile/sources_spec.rb
+++ b/spec/install/gemfile/sources_spec.rb
@@ -449,4 +449,75 @@ describe "bundle install with gems on multiple sources" do
       end
     end
   end
+
+  context "when a gem is installed to system gems" do
+    before do
+      install_gemfile! <<-G
+        source "file://#{gem_repo1}"
+        gem "rack"
+      G
+    end
+
+    context "and the gemfile changes" do
+      it "is still able to find that gem from remote sources" do
+        source_uri = "file://#{gem_repo1}"
+        second_uri = "file://#{gem_repo4}"
+
+        build_repo4 do
+          build_gem "rack", "2.0.1.1.forked"
+          build_gem "thor", "0.19.1.1.forked"
+        end
+
+        # When this gemfile is installed...
+        gemfile <<-G
+          # frozen_string_literal: true
+          source "#{source_uri}"
+
+          source "#{second_uri}" do
+            gem "rack", "2.0.1.1.forked"
+            gem "thor", "0.19.1.1.forked"
+          end
+          gem "rack-obama"
+        G
+
+        # It creates this lockfile.
+        lockfile <<-L
+          GEM
+            remote: #{source_uri}/
+            remote: #{second_uri}/
+            specs:
+              rack (2.0.1.1.forked)
+              rack-obama (1.0)
+                rack
+              thor (0.19.1.1.forked)
+
+          PLATFORMS
+            ruby
+
+          DEPENDENCIES
+            rack (= 2.0.1.1.forked)!
+            rack-obama
+            thor!
+
+          BUNDLED WITH
+             1.13.3
+        L
+
+        # Then we change the Gemfile by adding a version to thor
+        gemfile <<-G
+          # frozen_string_literal: true
+          source "#{source_uri}"
+
+          source "#{second_uri}" do
+            gem "rack", "2.0.1.1.forked"
+            gem "thor", "0.19.1.1.forked"
+          end
+          gem "rack-obama"
+        G
+
+        # But we should still be able to find rack 2.0.1.1.forked and install it
+        bundle! :install
+      end
+    end
+  end
 end