Merge 18c1d02d43 into f3bfc65607

test/mock.luau

@@ -66,6 +66,7 @@ local Instance = {} :: any do
         children: { Data },
         changed: { [string]: RBXScriptSignal },
         properties: { [string]: unknown },
+        tags: { [string]: true },
         destroying: RBXScriptSignal,
         class: string,
         type: "Instance"
@@ -158,6 +159,7 @@ local Instance = {} :: any do
             children = {},
             changed = {},
             properties = {},
+            tags = {},
             class = class,
             destroying = Signal.new() :: any,
             type = "Instance" :: "Instance"
@@ -211,6 +213,29 @@ local Instance = {} :: any do
         return data.changed[property]
     end
 
+    function methods.AddTag(userdata: userdata, tag: string)
+        if type(tag) ~= "string" then error("tag must be a string", 2) end
+        get_data(userdata).tags[tag] = true
+    end
+
+    function methods.RemoveTag(userdata: userdata, tag: string)
+        if type(tag) ~= "string" then error("tag must be a string", 2) end
+        get_data(userdata).tags[tag] = nil
+    end
+
+    function methods.HasTag(userdata: userdata, tag: string): boolean
+        if type(tag) ~= "string" then error("tag must be a string", 2) end
+        return get_data(userdata).tags[tag] == true
+    end
+
+    function methods.GetTags(userdata: userdata): { string }
+        local out = {}
+        for name in get_data(userdata).tags do
+            table.insert(out, name)
+        end
+        return out
+    end
+
     function methods.Destroy(userdata: userdata)
         local data = get_data(userdata);
         Signal.fire(data.destroying)

test/tests.luau

@@ -24,6 +24,7 @@ local vide = require "../../vide"
     local spring = vide.spring
     local action = vide.action
     local changed = vide.changed
+    local tag = vide.tag
     local apply = vide.apply
     local step = vide.step
 local graph = require "../../vide/src/graph"
@@ -2340,6 +2341,122 @@ TEST("changed()", wrap_root(function()
     end
 end))
 
+TEST("tag()", wrap_root(function()
+    do CASE "apply single tag"
+        local frame = create "Frame" {
+            tag("MyTag")
+        }
+
+        CHECK(frame:HasTag("MyTag"))
+        CHECK(#frame:GetTags() == 1)
+    end
+
+    do CASE "apply multiple tags"
+        local frame = create "Frame" {
+            tag({ "A", "B", "C" })
+        }
+
+        CHECK(frame:HasTag("A"))
+        CHECK(frame:HasTag("B"))
+        CHECK(frame:HasTag("C"))
+        CHECK(#frame:GetTags() == 3)
+    end
+
+    do CASE "compose multiple tag() actions"
+        local frame = create "Frame" {
+            tag("A"),
+            tag("B")
+        }
+
+        CHECK(frame:HasTag("A"))
+        CHECK(frame:HasTag("B"))
+    end
+
+    do CASE "remove tags on scope destroy"
+        local _, frame, destroy = root(function(destroy)
+            return create "Frame" {
+                tag({ "A", "B" })
+            }, destroy
+        end)
+
+        CHECK(frame:HasTag("A"))
+        CHECK(frame:HasTag("B"))
+
+        destroy()
+
+        CHECK(not frame:HasTag("A"))
+        CHECK(not frame:HasTag("B"))
+    end
+
+    do CASE "reactive single tag"
+        local current = source("A")
+
+        local frame = create "Frame" {
+            tag(current)
+        }
+
+        CHECK(frame:HasTag("A"))
+        CHECK(#frame:GetTags() == 1)
+
+        current("B")
+
+        CHECK(not frame:HasTag("A"))
+        CHECK(frame:HasTag("B"))
+        CHECK(#frame:GetTags() == 1)
+    end
+
+    do CASE "reactive multiple tags"
+        local current = source({ "A", "B" })
+
+        local frame = create "Frame" {
+            tag(current)
+        }
+
+        CHECK(frame:HasTag("A"))
+        CHECK(frame:HasTag("B"))
+        CHECK(#frame:GetTags() == 2)
+
+        -- preserve "A", remove "B", add "C"
+        current({ "A", "C" })
+
+        CHECK(frame:HasTag("A"))
+        CHECK(not frame:HasTag("B"))
+        CHECK(frame:HasTag("C"))
+        CHECK(#frame:GetTags() == 2)
+    end
+
+    do CASE "reactive tag removed on scope destroy"
+        local _, frame, destroy = root(function(destroy)
+            local current = source("A")
+            return create "Frame" {
+                tag(current)
+            }, destroy
+        end)
+
+        CHECK(frame:HasTag("A"))
+
+        destroy()
+
+        CHECK(not frame:HasTag("A"))
+        CHECK(#frame:GetTags() == 0)
+    end
+
+    do CASE "reactive tag derived from source"
+        local name = source("hello")
+
+        local frame = create "Frame" {
+            tag(function() return "prefix-" .. name() end)
+        }
+
+        CHECK(frame:HasTag("prefix-hello"))
+
+        name("world")
+
+        CHECK(not frame:HasTag("prefix-hello"))
+        CHECK(frame:HasTag("prefix-world"))
+    end
+end))
+
 TEST("batch()", wrap_root(function()
     do CASE "evaluation deferred"
         local a = source(0)