Allow running tests without a bundle

lib/ruby_lsp/listeners/test_discovery.rb

@@ -61,11 +61,26 @@ def calc_fully_qualified_name(name)
 
       #: (Prism::ClassNode node, String fully_qualified_name) -> Array[String]
       def calc_attached_ancestors(node, fully_qualified_name)
-        @index.linearized_ancestors_of(fully_qualified_name)
-      rescue RubyIndexer::Index::NonExistingNamespaceError
-        # When there are dynamic parts in the constant path, we will not have indexed the namespace. We can still
-        # provide test functionality if the class inherits directly from Test::Unit::TestCase or Minitest::Test
-        [node.superclass&.slice].compact
+        superclass = node.superclass
+
+        begin
+          ancestors = @index.linearized_ancestors_of(fully_qualified_name)
+          # If the project has no bundle and a test class inherits from `Minitest::Test`, the linearized ancestors will
+          # not include the parent class because we never indexed it in the first place. Here we add the superclass
+          # directly, so that we can support running tests in projects without a bundle
+          return ancestors if ancestors.length > 1
+
+          # If all we found is the class itself, then manually include the parent class
+          if ancestors.first == fully_qualified_name && superclass
+            return [*ancestors, superclass.slice]
+          end
+
+          ancestors
+        rescue RubyIndexer::Index::NonExistingNamespaceError
+          # When there are dynamic parts in the constant path, we will not have indexed the namespace. We can still
+          # provide test functionality if the class inherits directly from Test::Unit::TestCase or Minitest::Test
+          [superclass&.slice].compact
+        end
       end
 
       #: (Prism::ConstantPathNode | Prism::ConstantReadNode | Prism::ConstantPathTargetNode | Prism::CallNode | Prism::MissingNode node) -> String

lib/ruby_lsp/listeners/test_style.rb

@@ -145,7 +145,7 @@ def handle_test_unit_groups(file_path, groups_and_examples)
       MINITEST_REPORTER_PATH = File.expand_path("../test_reporters/minitest_reporter.rb", __dir__) #: String
       TEST_UNIT_REPORTER_PATH = File.expand_path("../test_reporters/test_unit_reporter.rb", __dir__) #: String
       BASE_COMMAND = begin
-        Bundler.with_original_env { Bundler.default_lockfile }
+        Bundler.with_unbundled_env { Bundler.default_lockfile }
         "bundle exec ruby"
       rescue Bundler::GemfileNotFound
         "ruby"

test/requests/discover_tests_test.rb

@@ -769,6 +769,29 @@ def test_spec_using_describe_with_additional_descriptions
       end
     end
 
+    def test_can_discover_tests_even_if_parent_class_was_not_indexed
+      source = <<~RUBY
+        class MyTest < Minitest::Test
+          def test_something; end
+        end
+      RUBY
+
+      with_server(source) do |server, uri|
+        server.process_message(id: 1, method: "rubyLsp/discoverTests", params: {
+          textDocument: { uri: uri },
+        })
+
+        items = get_response(server)
+
+        assert_equal(
+          ["MyTest"],
+          items.map { |i| i[:id] },
+        )
+        assert_equal(["MyTest#test_something"], items[0][:children].map { |i| i[:id] })
+        assert_all_items_tagged_with(items, :minitest)
+      end
+    end
+
     private
 
     def create_test_discovery_addon