Add hover functionality for dependencies in Gemfile (#1279)

* Add hover functionality to dependencies in Gemfile

* Add test case

* Always use currently loaded spec

* Incorporate feedback

* Add additional test cases

* Remove unused instance variable

* Remove leading whitespace from gem info

* Use safe navigation

* Cast info as String

* Skip assertion on gem description

lib/ruby_lsp/executor.rb

@@ -327,7 +327,7 @@ def hover(uri, position)
 
       # Instantiate all listeners
       dispatcher = Prism::Dispatcher.new
-      hover = Requests::Hover.new(@index, nesting, dispatcher, document.typechecker_enabled?)
+      hover = Requests::Hover.new(uri, @index, nesting, dispatcher, document.typechecker_enabled?)
 
       # Emit events for all listeners
       dispatcher.dispatch_once(target)

lib/ruby_lsp/requests/code_lens.rb

@@ -46,14 +46,6 @@ def provider
         end + " -Itest ",
         String,
       )
-      GEMFILE_NAME = T.let(
-        begin
-          Bundler.with_original_env { Bundler.default_gemfile.basename.to_s }
-        rescue Bundler::GemfileNotFound
-          "Gemfile"
-        end,
-        String,
-      )
       ACCESS_MODIFIERS = T.let([:public, :private, :protected], T::Array[Symbol])
       SUPPORTED_TEST_LIBRARIES = T.let(["minitest", "test-unit"], T::Array[String])
 

lib/ruby_lsp/requests/hover.rb

@@ -43,13 +43,15 @@ def provider
 
       sig do
         params(
+          uri: URI::Generic,
           index: RubyIndexer::Index,
           nesting: T::Array[String],
           dispatcher: Prism::Dispatcher,
           typechecker_enabled: T::Boolean,
         ).void
       end
-      def initialize(index, nesting, dispatcher, typechecker_enabled)
+      def initialize(uri, index, nesting, dispatcher, typechecker_enabled)
+        @path = T.let(uri.to_standardized_path, T.nilable(String))
         @index = index
         @nesting = nesting
         @_response = T.let(nil, ResponseType)
@@ -108,9 +110,15 @@ def on_constant_path_node_enter(node)
 
       sig { params(node: Prism::CallNode).void }
       def on_call_node_enter(node)
-        return if @typechecker_enabled
         return unless self_receiver?(node)
 
+        if @path && File.basename(@path) == GEMFILE_NAME && node.name == :gem
+          generate_gem_hover(node)
+          return
+        end
+
+        return if @typechecker_enabled
+
         message = node.message
         return unless message
 
@@ -142,6 +150,43 @@ def generate_hover(name, location)
           contents: markdown_from_index_entries(name, entries),
         )
       end
+
+      sig { params(node: Prism::CallNode).void }
+      def generate_gem_hover(node)
+        first_argument = node.arguments&.arguments&.first
+        return unless first_argument.is_a?(Prism::StringNode)
+
+        spec = Gem::Specification.find_by_name(first_argument.content)
+        return unless spec
+
+        info = T.let(
+          [
+            spec.description,
+            spec.summary,
+            "This rubygem does not have a description or summary.",
+          ].find { |text| !text.nil? && !text.empty? },
+          String,
+        )
+
+        # Remove leading whitespace if a heredoc was used for the summary or description
+        info = info.gsub(/^ +/, "")
+
+        markdown = <<~MARKDOWN
+          **#{spec.name}** (#{spec.version})
+
+          #{info}
+        MARKDOWN
+
+        @_response = Interface::Hover.new(
+          range: range_from_location(node.location),
+          contents: Interface::MarkupContent.new(
+            kind: Constant::MarkupKind::MARKDOWN,
+            value: markdown,
+          ),
+        )
+      rescue Gem::MissingSpecError
+        # Do nothing if the spec cannot be found
+      end
     end
   end
 end

lib/ruby_lsp/utils.rb

@@ -12,6 +12,14 @@ module RubyLsp
     end,
     T.nilable(String),
   )
+  GEMFILE_NAME = T.let(
+    begin
+      Bundler.with_original_env { Bundler.default_gemfile.basename.to_s }
+    rescue Bundler::GemfileNotFound
+      "Gemfile"
+    end,
+    String,
+  )
 
   # A notification to be sent to the client
   class Message

test/requests/hover_expectations_test.rb

@@ -157,6 +157,80 @@ class A
     T.must(message_queue).close
   end
 
+  def test_hovering_over_gemfile_dependency
+    message_queue = Thread::Queue.new
+    store = RubyLsp::Store.new
+
+    uri = URI("file:///Gemfile")
+    source = <<~RUBY
+      gem 'bundler'
+    RUBY
+    store.set(uri: uri, source: source, version: 1)
+
+    executor = RubyLsp::Executor.new(store, message_queue)
+    index = executor.instance_variable_get(:@index)
+    index.index_single(RubyIndexer::IndexablePath.new(nil, T.must(uri.to_standardized_path)), source)
+
+    stub_no_typechecker
+    response = executor.execute({
+      method: "textDocument/hover",
+      params: { textDocument: { uri: uri }, position: { character: 0, line: 0 } },
+    }).response
+
+    spec = Gem.loaded_specs["bundler"]
+
+    assert_includes(response.contents.value, spec.name)
+    assert_includes(response.contents.value, spec.version.to_s)
+  ensure
+    T.must(message_queue).close
+  end
+
+  def test_hovering_over_gemfile_dependency_with_missing_argument
+    message_queue = Thread::Queue.new
+    store = RubyLsp::Store.new
+
+    uri = URI("file:///Gemfile")
+    source = <<~RUBY
+      gem()
+    RUBY
+    store.set(uri: uri, source: source, version: 1)
+
+    executor = RubyLsp::Executor.new(store, message_queue)
+    index = executor.instance_variable_get(:@index)
+    index.index_single(RubyIndexer::IndexablePath.new(nil, T.must(uri.to_standardized_path)), source)
+
+    stub_no_typechecker
+    response = executor.execute({
+      method: "textDocument/hover",
+      params: { textDocument: { uri: uri }, position: { character: 0, line: 0 } },
+    }).response
+
+    assert_nil(response)
+  end
+
+  def test_hovering_over_gemfile_dependency_with_non_gem_argument
+    message_queue = Thread::Queue.new
+    store = RubyLsp::Store.new
+
+    uri = URI("file:///Gemfile")
+    source = <<~RUBY
+      gem(method_call)
+    RUBY
+    store.set(uri: uri, source: source, version: 1)
+
+    executor = RubyLsp::Executor.new(store, message_queue)
+    index = executor.instance_variable_get(:@index)
+    index.index_single(RubyIndexer::IndexablePath.new(nil, T.must(uri.to_standardized_path)), source)
+
+    stub_no_typechecker
+    response = executor.execute({
+      method: "textDocument/hover",
+      params: { textDocument: { uri: uri }, position: { character: 0, line: 0 } },
+    }).response
+
+    assert_nil(response)
+  end
+
   def test_hover_addons
     source = <<~RUBY
       # Hello