Add tests for hooks cache

test/hooks.luau

@@ -0,0 +1,47 @@
+local jecs = require("@jecs")
+
+local function create_cache(hook)
+    local columns = setmetatable({}, {
+        __index = function(self, component)
+            local column = {}
+            self[component] = column
+            return column
+        end
+    })
+
+    return function(world, component, fn)
+        local column = columns[component]
+        table.insert(column, fn)
+        world:set(component, hook, function(entity, value)
+            for _, callback in column do
+                callback(entity, value)
+            end
+        end)
+    end
+end
+
+local hooks = {
+    OnSet = create_cache(jecs.OnSet),
+    OnAdd = create_cache(jecs.OnAdd),
+    OnRemove = create_cache(jecs.OnRemove)
+}
+
+local world = jecs.World.new()
+local Position = world:component()
+local order = ""
+hooks.OnSet(world, Position, function(entity, value)
+    print("$1", entity, `({value.x}, {value.y}, {value.z})`)
+    order ..= "$1"
+end)
+hooks.OnSet(world, Position, function(entity, value)
+    print("$2", entity, `\{{value.x}, {value.y}, {value.z}}`)
+    order ..= "-$2"
+end)
+
+world:set(world:entity(), Position, {x=1,y=0,z=1})
+
+-- Output:
+--  $1      270     (1, 0, 1)
+--  $2      270     {1, 0, 1}
+
+assert(order == "$1".."-".."$2")