CI fails with with different bundler execution

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## Master (unreleased)
 
+* Fix issue where the wrong version of bundler is used on CI apps (https://github.com/heroku/heroku-buildpack-ruby/pull/961)
 * Remove libpq external dependency (https://github.com/heroku/heroku-buildpack-ruby/pull/959)
 
 ## v210 (3/6/2020)

bin/support/ruby_test

@@ -30,19 +30,20 @@ def execute_command(command)
 end
 
 # $ bin/test BUILD_DIR ENV_DIR ARTIFACT_DIR
-build_dir, env_dir, artifact_dir = ARGV
+build_dir, env_dir, _ = ARGV
 LanguagePack::ShellHelpers.initialize_env(env_dir)
 
+bundler = LanguagePack::Helpers::BundlerWrapper.new(
+  gemfile_path: "#{build_dir}/Gemfile"
+)
+
 # The `ruby_test-compile` program installs a version of Ruby for the
 # user's application. It needs the propper `PATH`, where ever Ruby is installed
 # we always add a symlink to the `bin/ruby` file so that is always valid.
 # We calculate the gem path the same way we do when compiling.
-LanguagePack::ShellHelpers.user_env_hash["PATH"] = "#{build_dir}/bin:#{ENV["PATH"]}"
+LanguagePack::ShellHelpers.user_env_hash["PATH"] = "#{build_dir}/bin:#{bundler.bundler_path}/bin:#{ENV["PATH"]}"
 LanguagePack::ShellHelpers.user_env_hash["GEM_PATH"] = LanguagePack::Ruby.slug_vendor_base
 
-bundler = LanguagePack::Helpers::BundlerWrapper.new(
-  gemfile_path: "#{build_dir}/Gemfile"
-)
 # load bundler
 bundler.install
 

hatchet.json

@@ -99,6 +99,7 @@
     "sharpstone/rails_31_ruby_schema_format",
     "sharpstone/rails_31_sql_schema_format",
     "sharpstone/ruby_no_rails_test",
-    "sharpstone/activerecord_rake_tasks_does_not_exist"
+    "sharpstone/activerecord_rake_tasks_does_not_exist",
+    "sharpstone/ci_fails_ruby_default_bundler"
   ]
 }

hatchet.lock

@@ -15,6 +15,8 @@
   - 116db685f54dae18f703b3beb90e64fdbddb048d
 - - "./repos/ci/activerecord_rake_tasks_does_not_exist"
   - a6b711be6921cf7a0aa4e31269c37965799ea110
+- - "./repos/ci/ci_fails_ruby_default_bundler"
+  - 43cbf196245957be6242b1e1bc56b8f1bfa00004
 - - "./repos/ci/heroku-ci-json-example"
   - 4e5410a7381f486ba3df7739e02e52f32fdd4dda
 - - "./repos/ci/rails5_ruby_schema_format"

spec/hatchet/ci_spec.rb

@@ -38,4 +38,10 @@
       expect(test_run.output).to_not match("db:migrate")
     end
   end
+
+  it "works when using a Ruby version different from default with an older version of bundler and not declaring a test script" do
+    Hatchet::Runner.new("ci_fails_ruby_default_bundler").run_ci do |test_run|
+      expect(test_run.output).to match("rspec")
+    end
+  end
 end