Test requiring missing absolute paths

Fixes #196

lib/sprockets/asset_attributes.rb

@@ -50,7 +50,7 @@ def logical_path
         path = "#{path}#{engine_format_extension}" unless format_extension
         path
       else
-        raise Error, "#{pathname} isn't in paths: #{environment.paths.join(', ')}"
+        raise FileOutsidePaths, "#{pathname} isn't in paths: #{environment.paths.join(', ')}"
       end
     end
 

lib/sprockets/errors.rb

@@ -6,6 +6,7 @@ class CircularDependencyError < Error; end
   class ContentTypeMismatch     < Error; end
   class EncodingError           < Error; end
   class FileNotFound            < Error; end
+  class FileOutsidePaths        < Error; end
 
   module EngineError
     attr_accessor :sprockets_annotation

test/fixtures/asset/absolute/require_nonexistent_path.js

@@ -0,0 +1 @@
+//= require_tree /missing

test/fixtures/asset/absolute/require_outside_path.js.erb

@@ -0,0 +1 @@
+//= require /bin/sh

test/test_asset.rb

@@ -298,6 +298,12 @@ def setup
     end
   end
 
+  test "can't require absolute files outside the load path" do
+    assert_raise Sprockets::FileOutsidePaths do
+      warn asset("absolute/require_outside_path.js").to_s
+    end
+  end
+
   test "require_directory requires all child files in alphabetical order" do
     assert_equal(
       "ok(\"b.js.erb\");\n",
@@ -345,6 +351,12 @@ def setup
     end
   end
 
+  test "require_tree with a nonexistent absolute path raises an exception" do
+    assert_raise(Sprockets::ArgumentError) do
+      asset("absolute/require_nonexistent_path.js").to_s
+    end
+  end
+
   test "require_tree respects order of child dependencies" do
     assert_equal(
       "var c;\nvar b;\nvar a;\n\n",