[web] [tests] introduce elementBuilderShouldBeCalledOnce test

web/core/src/jsTest/kotlin/elements/ElementsTests.kt

@@ -6,6 +6,8 @@
 package org.jetbrains.compose.web.core.tests.elements
 
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import kotlinx.browser.document
 import org.jetbrains.compose.web.ExperimentalComposeWebApi
 import org.jetbrains.compose.web.attributes.AttrsBuilder
 import org.jetbrains.compose.web.testutils.*
@@ -131,4 +133,30 @@ class ElementsTests {
 
         assertEquals("<div><custom id=\"container\">CUSTOM</custom></div>", root.outerHTML)
     }
+
+    @Test
+    fun elementBuilderShouldBeCalledOnce() = runTest {
+        var counter = 0
+        var flag = false
+
+        composition {
+            TagElement({
+                counter++
+                document.createElement("div")
+            }, null,
+                if (flag) {
+                    { Div() { Text("ON") } }
+                } else null
+            )
+
+        }
+
+        assertEquals(1, counter, )
+
+        flag = true
+        waitForRecompositionComplete()
+
+        assertEquals(1, counter)
+        assertEquals("<div><div>ON</div></div>", nextChild().outerHTML)
+    }
 }