[ruby/fiddle] Make array access override compatible with base class (#25)

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

* Make accessing a struct's underlying memory more convenient.

* refactor memory access unit tests for improved clarity


https://github.com/ruby/fiddle/commit/c082c81bb5

1 files changed, 22 insertions, 0 deletions

diff --git a/test/fiddle/test_import.rb b/test/fiddle/test_import.rb
index 99294ea161..778327b4b2 100644
--- a/test/fiddle/test_import.rb
+++ b/test/fiddle/test_import.rb
@@ -54,6 +54,28 @@ module Fiddle
       assert_match(/call dlload before/, err.message)
     end
 
+    def test_struct_memory_access()
+      # check memory operations performed directly on struct
+      my_struct = Fiddle::Importer.struct(['int id']).malloc
+      my_struct[0, Fiddle::SIZEOF_INT] = "\x01".b * Fiddle::SIZEOF_INT
+      assert_equal 0x01010101, my_struct.id
+
+      my_struct.id = 0
+      assert_equal "\x00".b * Fiddle::SIZEOF_INT, my_struct[0, Fiddle::SIZEOF_INT]
+    end
+
+    def test_struct_ptr_array_subscript_multiarg()
+      # check memory operations performed on struct#to_ptr
+      struct = Fiddle::Importer.struct([ 'int x' ]).malloc
+      ptr = struct.to_ptr
+
+      struct.x = 0x02020202
+      assert_equal("\x02".b * Fiddle::SIZEOF_INT, ptr[0, Fiddle::SIZEOF_INT])
+
+      ptr[0, Fiddle::SIZEOF_INT] = "\x01".b * Fiddle::SIZEOF_INT
+      assert_equal 0x01010101, struct.x
+    end
+
     def test_malloc()
       s1 = LIBC::Timeval.malloc()
       s2 = LIBC::Timeval.malloc()