[ruby/fiddle] Fix assignment to array within struct (#26)

* Allow access to a struct's underlying memory with `struct[offset, length]`.

https://github.com/ruby/fiddle/commit/24083690a6

1 files changed, 14 insertions, 0 deletions

diff --git a/test/fiddle/test_import.rb b/test/fiddle/test_import.rb
index 778327b4b2..867f6960ee 100644
--- a/test/fiddle/test_import.rb
+++ b/test/fiddle/test_import.rb
@@ -129,6 +129,20 @@ module Fiddle
       assert_equal([0,1,2], ary.value)
     end
 
+    def test_struct_array_assignment()
+      instance = Fiddle::Importer.struct(["unsigned int stages[3]"]).malloc
+      instance.stages[0] = 1024
+      instance.stages[1] = 10
+      instance.stages[2] = 100
+      assert_equal 1024, instance.stages[0]
+      assert_equal 10, instance.stages[1]
+      assert_equal 100, instance.stages[2]
+      assert_equal [1024, 10, 100].pack(Fiddle::PackInfo::PACK_MAP[-Fiddle::TYPE_INT] * 3),
+                   instance.to_ptr[0, 3 * Fiddle::SIZEOF_INT]
+      assert_raise(IndexError) { instance.stages[-1] = 5 }
+      assert_raise(IndexError) { instance.stages[3] = 5 }
+    end
+
     def test_struct()
       s = LIBC::MyStruct.malloc()
       s.num = [0,1,2,3,4]