Library#locate_ref returns nil for unresolved requires (#675)

lib/solargraph/library.rb

@@ -258,6 +258,10 @@ def locate_pins location
       api_map.locate_pins(location).map { |pin| pin.realize(api_map) }
     end
 
+    # Match a require reference to a file.
+    #
+    # @param location [Location]
+    # @return [Location, nil]
     def locate_ref location
       map = source_map_hash[location.filename]
       return if map.nil?
@@ -268,7 +272,7 @@ def locate_ref location
         next unless source_map_hash.key?(full)
         return Location.new(full, Solargraph::Range.from_to(0, 0, 0, 0))
       end
-      # api_map.yard_map.require_reference(pin.name)
+      nil
     rescue FileNotFoundError
       nil
     end

spec/fixtures/workspace/app.rb

@@ -1,2 +1,4 @@
+require 'not_a_file'
+
 thing = Thing.new
 thing.do_thing

spec/library_spec.rb

@@ -452,6 +452,17 @@ def bar; end
     expect(library.current).to be_nil
   end
 
+  describe '#locate_ref' do
+    it 'returns nil without a matching reference location' do
+      workspace = File.absolute_path(File.join('spec', 'fixtures', 'workspace'))
+      library = Solargraph::Library.load(workspace)
+      library.map!
+      location = Solargraph::Location.new(File.join(workspace, 'app.rb'), Solargraph::Range.from_to(0, 8, 0, 8))
+      found = library.locate_ref(location)
+      expect(found).to be_nil
+    end
+  end
+
   context 'unsynchronized' do
     let(:library) { Solargraph::Library.load File.absolute_path(File.join('spec', 'fixtures', 'workspace')) }
     let(:good_file) { File.join(library.workspace.directory, 'lib', 'thing.rb') }