Expose children propery for TestFlexContainer

Used when we need to notify the parent with change in children's modifier `children.onModifierUpdated`

redwood-layout-composeui/src/androidUnitTest/kotlin/app/cash/redwood/layout/composeui/ComposeUiFlexContainerTest.kt

@@ -25,6 +25,7 @@ import app.cash.redwood.layout.AbstractFlexContainerTest
 import app.cash.redwood.layout.TestFlexContainer
 import app.cash.redwood.layout.widget.FlexContainer
 import app.cash.redwood.widget.Widget
+import app.cash.redwood.widget.compose.ComposeWidgetChildren
 import app.cash.redwood.yoga.FlexDirection
 import com.android.resources.LayoutDirection
 import com.google.testing.junit.testparameterinjector.TestParameter
@@ -67,7 +68,7 @@ class ComposeUiFlexContainerTest(
     private val delegate: ComposeUiFlexContainer,
   ) : TestFlexContainer<@Composable () -> Unit>, FlexContainer<@Composable () -> Unit> by delegate {
     private var childCount = 0
-
+    override val children: ComposeWidgetChildren = delegate.children
     constructor(direction: FlexDirection, backgroundColor: Int) : this(
       ComposeUiFlexContainer(direction).apply {
         testOnlyModifier = Modifier.background(Color(backgroundColor))

redwood-layout-shared-test/src/commonMain/kotlin/app/cash/redwood/layout/AbstractFlexContainerTest.kt

@@ -563,7 +563,6 @@ abstract class AbstractFlexContainerTest<T : Any> {
   private fun testContainerWithChildrenModifierChanges(
     flexDirection: FlexDirection,
   ) {
-    assumeTrue(flexDirection in listOf(FlexDirection.Row, FlexDirection.Column))
     val container = flexContainer(flexDirection)
     container.width(Constraint.Fill)
     container.height(Constraint.Fill)
@@ -577,13 +576,15 @@ abstract class AbstractFlexContainerTest<T : Any> {
     container.onEndChanges()
     verifySnapshot(container, "Margin")
     first.modifier = Modifier
+    container.children.onModifierUpdated(0, first)
     container.onEndChanges()
     verifySnapshot(container, "Empty")
   }
 }
 
 interface TestFlexContainer<T : Any> : Widget<T>, ChangeListener {
   override val value: T
+  val children: Widget.Children<T>
   fun width(width: Constraint)
   fun height(height: Constraint)
   fun crossAxisAlignment(crossAxisAlignment: CrossAxisAlignment)

redwood-layout-uiview/src/commonTest/kotlin/app/cash/redwood/layout/uiview/UIViewFlexContainerTest.kt

@@ -48,6 +48,7 @@ class UIViewFlexContainerTest(
     private val delegate: UIViewFlexContainer,
   ) : TestFlexContainer<UIView>, FlexContainer<UIView> by delegate, ChangeListener by delegate {
     private var childCount = 0
+    override val children: Widget.Children<UIView> = delegate.children
 
     init {
       value.backgroundColor = UIColor(red = 0.0, green = 0.0, blue = 1.0, alpha = 0.2)

redwood-layout-view/src/test/kotlin/app/cash/redwood/layout/view/ViewFlexContainerTest.kt

@@ -22,6 +22,7 @@ import app.cash.redwood.layout.AbstractFlexContainerTest
 import app.cash.redwood.layout.TestFlexContainer
 import app.cash.redwood.layout.widget.FlexContainer
 import app.cash.redwood.widget.ChangeListener
+import app.cash.redwood.widget.ViewGroupChildren
 import app.cash.redwood.widget.Widget
 import app.cash.redwood.yoga.FlexDirection
 import com.android.resources.LayoutDirection
@@ -66,7 +67,7 @@ class ViewFlexContainerTest(
     private val delegate: ViewFlexContainer,
   ) : TestFlexContainer<View>, FlexContainer<View> by delegate, ChangeListener by delegate {
     private var childCount = 0
-
+    override val children: ViewGroupChildren = delegate.children
     override fun add(widget: Widget<View>) {
       addAt(childCount, widget)
     }

redwood-lazylayout-composeui/src/androidUnitTest/kotlin/app/cash/redwood/layout/composeui/ComposeUiLazyListTest.kt

@@ -38,6 +38,7 @@ import app.cash.redwood.layout.widget.Row
 import app.cash.redwood.lazylayout.composeui.ComposeUiLazyList
 import app.cash.redwood.lazylayout.widget.LazyList
 import app.cash.redwood.widget.Widget
+import app.cash.redwood.widget.compose.ComposeWidgetChildren
 import app.cash.redwood.yoga.FlexDirection
 import com.android.resources.LayoutDirection
 import com.google.testing.junit.testparameterinjector.TestParameter
@@ -113,6 +114,8 @@ class ComposeUiLazyListTest(
       },
     )
 
+    override val children: ComposeWidgetChildren = delegate.items
+
     override fun mainAxisAlignment(mainAxisAlignment: MainAxisAlignment) {
     }
 

redwood-lazylayout-view/src/test/kotlin/app/cash/redwood/lazylayout/view/ViewLazyListTest.kt

@@ -99,6 +99,8 @@ class ViewLazyListTest(
       },
     )
 
+    override val children: Widget.Children<View> = delegate.items
+
     override fun mainAxisAlignment(mainAxisAlignment: MainAxisAlignment) {
     }