Fix signature help for clients that don't support the context param (#1285)

Author: vinistock

lib/ruby_lsp/executor.rb

@@ -247,11 +247,11 @@ def perform_initial_indexing
       params(
         uri: URI::Generic,
         position: T::Hash[Symbol, T.untyped],
-        context: T::Hash[Symbol, T.untyped],
+        context: T.nilable(T::Hash[Symbol, T.untyped]),
       ).returns(T.any(T.nilable(Interface::SignatureHelp), T::Hash[Symbol, T.untyped]))
     end
     def signature_help(uri, position, context)
-      current_signature = context[:activeSignatureHelp]
+      current_signature = context && context[:activeSignatureHelp]
       document = @store.get(uri)
       target, parent, nesting = document.locate_node(
         { line: position[:line], character: position[:character] - 2 },
@@ -270,7 +270,7 @@ def signature_help(uri, position, context)
       end
 
       dispatcher = Prism::Dispatcher.new
-      listener = Requests::SignatureHelp.new(context, nesting, @index, dispatcher)
+      listener = Requests::SignatureHelp.new(nesting, @index, dispatcher)
       dispatcher.dispatch_once(target)
       listener.response
     end

lib/ruby_lsp/requests/signature_help.rb

@@ -45,14 +45,12 @@ def provider
 
       sig do
         params(
-          context: T::Hash[Symbol, T.untyped],
           nesting: T::Array[String],
           index: RubyIndexer::Index,
           dispatcher: Prism::Dispatcher,
         ).void
       end
-      def initialize(context, nesting, index, dispatcher)
-        @context = context
+      def initialize(nesting, index, dispatcher)
         @nesting = nesting
         @index = index
         @_response = T.let(nil, ResponseType)

test/requests/signature_help_test.rb

@@ -219,6 +219,37 @@ def baz
     assert_equal(1, result.active_parameter)
   end
 
+  def test_requests_missing_context
+    document = RubyLsp::RubyDocument.new(source: +<<~RUBY, version: 1, uri: @uri)
+      class Foo
+        def bar(a, b)
+        end
+
+        def baz
+          bar()
+        end
+      end
+    RUBY
+
+    @store.set(uri: @uri, source: document.source, version: 1)
+
+    index = @executor.instance_variable_get(:@index)
+    index.index_single(RubyIndexer::IndexablePath.new(nil, @uri.to_standardized_path), document.source)
+
+    result = run_request(
+      method: "textDocument/signatureHelp",
+      params: {
+        textDocument: { uri: @uri.to_s },
+        position: { line: 5, character: 7 },
+      },
+    )
+
+    signature = result.signatures.first
+
+    assert_equal("bar(a, b)", signature.label)
+    assert_equal(0, result.active_parameter)
+  end
+
   private
 
   def run_request(method:, params: {})