[Runtime] Print a more helpful error when gem activation conflicts with a default gemseg-test-default-gem-substitutes-are-activated

3 files changed, 72 insertions, 13 deletions

diff --git a/lib/bundler/rubygems_integration.rb b/lib/bundler/rubygems_integration.rb
index 66497add02..7283a326dd 100644
--- a/lib/bundler/rubygems_integration.rb
+++ b/lib/bundler/rubygems_integration.rb
@@ -74,12 +74,16 @@ module Bundler
     def spec_missing_extensions?(spec, default = true)
       return spec.missing_extensions? if spec.respond_to?(:missing_extensions?)
 
-      return false if spec.respond_to?(:default_gem?) && spec.default_gem?
+      return false if spec_default_gem?(spec)
       return false if spec.extensions.empty?
 
       default
     end
 
+    def spec_default_gem?(spec)
+      spec.respond_to?(:default_gem?) && spec.default_gem?
+    end
+
     def stub_set_spec(stub, spec)
       stub.instance_variable_set(:@spec, spec)
     end
diff --git a/lib/bundler/runtime.rb b/lib/bundler/runtime.rb
index 5bdc9dfa63..5540509d74 100644
--- a/lib/bundler/runtime.rb
+++ b/lib/bundler/runtime.rb
@@ -29,18 +29,7 @@ module Bundler
           raise GemNotFound, "#{spec.full_name} is missing. Run `bundle install` to get it."
         end
 
-        if (activated_spec = Bundler.rubygems.loaded_specs(spec.name)) && activated_spec.version != spec.version
-          e = Gem::LoadError.new "You have already activated #{activated_spec.name} #{activated_spec.version}, " \
-                                 "but your Gemfile requires #{spec.name} #{spec.version}. Prepending " \
-                                 "`bundle exec` to your command may solve this."
-          e.name = spec.name
-          if e.respond_to?(:requirement=)
-            e.requirement = Gem::Requirement.new(spec.version.to_s)
-          else
-            e.version_requirement = Gem::Requirement.new(spec.version.to_s)
-          end
-          raise e
-        end
+        check_for_activated_spec!(spec)
 
         Bundler.rubygems.mark_loaded(spec)
         spec.load_paths.reject {|path| $LOAD_PATH.include?(path) }
@@ -305,5 +294,27 @@ module Bundler
 
       output
     end
+
+    def check_for_activated_spec!(spec)
+      return unless activated_spec = Bundler.rubygems.loaded_specs(spec.name)
+      return if activated_spec.version == spec.version
+
+      suggestion = if Bundler.rubygems.spec_default_gem?(activated_spec)
+        "Since #{spec.name} is a default gem, you can either remove your dependency on it" \
+        " or try updating to a newer version of bundler that supports #{spec.name} as a default gem."
+      else
+        "Prepending `bundle exec` to your command may solve this."
+      end
+
+      e = Gem::LoadError.new "You have already activated #{activated_spec.name} #{activated_spec.version}, " \
+                             "but your Gemfile requires #{spec.name} #{spec.version}. #{suggestion}"
+      e.name = spec.name
+      if e.respond_to?(:requirement=)
+        e.requirement = Gem::Requirement.new(spec.version.to_s)
+      else
+        e.version_requirement = Gem::Requirement.new(spec.version.to_s)
+      end
+      raise e
+    end
   end
 end
diff --git a/spec/runtime/setup_spec.rb b/spec/runtime/setup_spec.rb
index b19a81e75f..120aa03d7e 100644
--- a/spec/runtime/setup_spec.rb
+++ b/spec/runtime/setup_spec.rb
@@ -1197,6 +1197,50 @@ end
         expect(err).to eq("")
         expect(out).to eq("{}")
       end
+
+      let(:default_gems) do
+        ruby!(<<-RUBY).split("\n")
+          if Gem::Specification.is_a?(Enumerable)
+            puts Gem::Specification.select(&:default_gem?).map(&:name)
+          end
+        RUBY
+      end
+
+      it "activates newer versions of default gems" do
+        build_repo4 do
+          default_gems.each do |g|
+            build_gem g, "999999"
+          end
+        end
+
+        install_gemfile! <<-G
+          source "file:#{gem_repo4}"
+          #{default_gems}.each do |g|
+            gem g, "999999"
+          end
+        G
+
+        expect(the_bundle).to include_gems(*default_gems.map {|g| "#{g} 999999" })
+      end
+
+      it "activates older versions of default gems" do
+        build_repo4 do
+          default_gems.each do |g|
+            build_gem g, "0.0.0.a"
+          end
+        end
+
+        default_gems.reject! {|g| exemptions.include?(g) }
+
+        install_gemfile! <<-G
+          source "file:#{gem_repo4}"
+          #{default_gems}.each do |g|
+            gem g, "0.0.0.a"
+          end
+        G
+
+        expect(the_bundle).to include_gems(*default_gems.map {|g| "#{g} 0.0.0.a" })
+      end
     end
   end