national_grid.gemspec in national_grid-0.1.1 vs national_grid.gemspec in national_grid-0.1.2

@@ -1,18 +1,42 @@
-lib = File.expand_path("../lib", __FILE__)
+lib = File.expand_path("lib", __dir__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require "national_grid/version"
 
+module Files
+  module_function
+
+  def all
+    git_files + git_submodule_files
+  end
+
+  def git_files(dir = ".")
+    Dir.chdir File.expand_path(dir, __dir__) do
+      `git ls-files -z`.split("\x0")
+    end
+  end
+
+  def git_submodules
+    `git submodule -q foreach 'printf "$path\\0"'`.split("\x0")
+  end
+
+  def git_submodule_files
+    git_submodules.flat_map {|submodule|
+      git_files(submodule).map {|file| File.join(submodule, file)}
+    }
+  end
+end
+
 Gem::Specification.new do |spec|
   spec.name          = "national_grid"
   spec.version       = NationalGrid::VERSION
   spec.authors       = ["Andrew Haines"]
   spec.email         = ["[e-mail]"]
   spec.summary       = "Converts between Ordnance Survey National Grid easting-northing coordinates and GPS latitude-longitude coordinates"
   spec.homepage      = "https://github.com/haines/national_grid"
   spec.license       = "MIT"
 
-  spec.files         = `git ls-files -z`.split("\x0")
+  spec.files         = Files.all
   spec.test_files    = spec.files.grep(%r{^test/})
   spec.require_paths = ["lib"]
   spec.extensions    = ["ext/national_grid/extconf.rb"]
 
   spec.add_development_dependency "bundler", "~> 1.5"