add an 'equals' method to ItemStack and compatibility w/ lua '==' (#12771)

Co-authored-by: rubenwardy <rw@rubenwardy.com>
Co-authored-by: sfan5 <sfan5@live.de>

games/devtest/mods/unittests/itemstack_equals.lua

@@ -0,0 +1,74 @@
+local function test_itemstack_equals_non_stack()
+	local i1 = ItemStack("basenodes:stone")
+	local i2 = { foo = "bar" }
+
+	assert(not i1:equals(i2))
+	assert(i1 ~= i2)
+	assert(i2 ~= i1)
+end
+
+unittests.register("test_itemstack_equals_non_stack", test_itemstack_equals_non_stack)
+
+local function test_itemstack_equals_name()
+	local i1 = ItemStack("basenodes:stone")
+	local i2 = ItemStack("basenodes:desert_stone")
+
+	assert(not i1:equals(i2))
+	assert(i1 ~= i2)
+end
+
+unittests.register("test_itemstack_equals_name", test_itemstack_equals_name)
+
+local function test_itemstack_equals_count()
+	local i1 = ItemStack("basenodes:stone")
+	local i2 = ItemStack("basenodes:stone 2")
+
+	assert(not i1:equals(i2))
+	assert(i1 ~= i2)
+end
+
+unittests.register("test_itemstack_equals_count", test_itemstack_equals_count)
+
+local function test_itemstack_equals_wear()
+	local i1 = ItemStack("basetools:axe_stone")
+	local i2 = ItemStack("basetools:axe_stone")
+
+	i2:add_wear(1)
+
+	assert(not i1:equals(i2))
+	assert(i1 ~= i2)
+end
+
+unittests.register("test_itemstack_equals_wear", test_itemstack_equals_wear)
+
+local function test_itemstack_equals_metadata()
+	local i1 = ItemStack("basenodes:stone")
+	local i2 = ItemStack("basenodes:stone")
+	local i3 = ItemStack("basenodes:stone")
+
+	local m1 = i1:get_meta()
+	local m2 = i2:get_meta()
+	local m3 = i3:get_meta()
+
+	local keys = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p"}
+	local values = {}
+
+	for i, key in pairs(keys) do
+		m1:set_int(key, i)
+		m3:set_int(key, i)
+		values[key] = i
+	end
+
+	m3:set_int("a", 999)
+
+	for key, i in pairs(values) do
+		m2:set_int(key, i)
+	end
+
+	assert(i1:equals(i2))
+	assert(i1 == i2)
+	assert(not i1:equals(i3))
+	assert(i1 ~= i3)
+end
+
+unittests.register("test_itemstack_equals_metadata", test_itemstack_equals_metadata)