Add test

src/init.luau

@@ -674,7 +674,7 @@ export type Query = typeof(EmptyQuery)
 
 type CompatibleArchetype = { archetype: Archetype, indices: { number } }
 
-local function replaceColumns(row, columns, ...)
+local function replaceMult(row, columns, ...)
 	for i, column in columns do
 		column[row] = select(i, ...)
 	end
@@ -800,10 +800,9 @@ local function preparedQuery(compatibleArchetypes: { Archetype },
 		return queryNext
 	end
 
-	local function replace(fn)
+	local function replace(_, fn)
-        for _, compatibleArchetype in compatibleArchetypes do
+        for i, archetype in compatibleArchetypes do
-			local archetype = compatibleArchetype.archetype
+			local tr = indices[i]
-			local tr = compatibleArchetype.indices
 			local columns = archetype.columns
 
 			for row in archetype.entities do
@@ -835,7 +834,7 @@ local function preparedQuery(compatibleArchetypes: { Archetype },
 					for i = 1, queryLength do
 						queryOutput[i] = columns[tr[i]][row]
 					end
-					replaceColumns(row, columns, fn(unpack(queryOutput)))
+					replaceMult(row, columns, fn(unpack(queryOutput)))
 				end
 			end
 		end

tests/world.luau

@@ -451,6 +451,26 @@ TEST("world", function()
 
 		CHECK(count == 2)
 	end
+
+	do CASE "should replace component data"
+        local world = jecs.World.new()
+		local A = world:component()
+		local B = world:component()
+	    local C = world:component()
+
+		local e = world:entity()
+		world:set(e, A, 1)
+		world:set(e, B, true)
+		world:set(e, C, "hello ")
+
+		world:query(A, B, C):replace(function(a, b, c)
+		    return a * 2, not b, c.."world"
+		end)
+
+		CHECK(world:get(e, A) == 2)
+		CHECK(world:get(e, B) == false)
+		CHECK(world:get(e, C) == "hello world")
+	end
 end)
 
 FINISH()