Add hexadecimal exercise

hexadecimal.lua

@@ -0,0 +1,34 @@
+-- Solution --------------------------------------------------------------------
+function hexadecimal(x)
+	-- Your implementation here
+end
+
+-- Tests -----------------------------------------------------------------------
+
+local luaunit = require("luaunit.luaunit")
+
+function test_hexadecimal_of_8_is_8()
+	luaunit.assertEquals(hexadecimal(8), "8")
+end
+
+function test_hexadecimal_of_14_is_e()
+	luaunit.assertEquals(hexadecimal(14), "e")
+end
+
+function test_hexadecimal_of_42_is_2a()
+	luaunit.assertEquals(hexadecimal(42), "2a")
+end
+
+function test_hexadecimal_of_3735928559_is_deadbeef()
+	luaunit.assertEquals(hexadecimal(3735928559), "deadbeef")
+end
+
+function test_hexadecimal_of_12648430_is_c0ffee()
+	luaunit.assertEquals(hexadecimal(12648430), "c0ffee")
+end
+
+function test_hexadecimal_of_49374_is_c0de()
+	luaunit.assertEquals(hexadecimal(49374), "c0de")
+end
+
+os.exit(luaunit.LuaUnit.run())