util.array: Add a test case for a behavior change in Lua 5.3
In Lua 5.1 and 5.2 the __eq metamethod is not invoked if the other
argument is of a different metatable, but in Lua 5.3 it is.
--- a/spec/util_array_spec.lua Sun Jan 12 20:36:21 2020 +0100
+++ b/spec/util_array_spec.lua Tue Jan 14 23:39:47 2020 +0100
@@ -43,6 +43,7 @@
local b = array({ "c", "d" });
assert.truthy(a1 == a2);
assert.falsy(a1 == b);
+ assert.falsy(a1 == { "a", "b" }, "Behavior of metatables changed in Lua 5.3");
end);
end);