Load dependencies even with -r option

lib/rbs/environment_loader.rb

@@ -38,12 +38,23 @@ def initialize(core_root: DEFAULT_CORE_ROOT, repository: Repository.new)
       @dirs = []
     end
 
-    def add(path: nil, library: nil, version: nil)
+    def add(path: nil, library: nil, version: nil, resolve_dependency: true)
       case
       when path
         dirs << path
       when library
         libs << Library.new(name: library, version: version)
+        if resolve_dependency
+          [Collection::Sources::Rubygems.instance, Collection::Sources::Stdlib.instance].each do |source|
+            gem = {'name' => library, 'version' => version}
+            next unless source.has?(gem)
+
+            source.dependencies_of(gem)&.each do |dep|
+              add(library: dep['name'])
+            end
+            break
+          end
+        end
       end
     end
 
@@ -53,7 +64,7 @@ def add_collection(collection_config)
       repository.add(collection_config.repo_path)
 
       collection_config.gems.each do |gem|
-        add(library: gem['name'], version: gem['version'])
+        add(library: gem['name'], version: gem['version'], resolve_dependency: false)
       end
     end