simplify singles

develop/untests.lua

@@ -1,2 +1,3 @@
 require 'develop.untests.idpools_untests'
 require 'develop.untests.registry_untests'
+require 'develop.untests.singles_untests'

develop/untests/singles_untests.lua

@@ -0,0 +1,33 @@
+---@diagnostic disable: invisible
+local evo = require 'evolved.evolved'
+
+do
+    local e = evo.registry.entity()
+    assert(not evo.singles.has(e))
+    assert(evo.singles.get(e) == nil)
+
+    assert(evo.singles.set(e, 42))
+    assert(evo.singles.has(e))
+    assert(evo.singles.get(e) == 42)
+end
+
+do
+    local s = evo.singles.single()
+    assert(evo.singles.has(s))
+    assert(evo.singles.get(s) == true)
+
+    assert(s == evo.singles.set(s, 42))
+    assert(evo.singles.get(s) == 42)
+end
+
+do
+    local s = evo.singles.single(42)
+    assert(evo.singles.has(s))
+    assert(evo.singles.get(s) == 42)
+
+    assert(s == evo.singles.set(s, true))
+    assert(evo.singles.get(s) == true)
+
+    assert(s == evo.singles.set(s, false))
+    assert(evo.singles.get(s) == false)
+end