test: regression test for detached onPlaced crash (#639)

multiplatform-markdown-renderer/build.gradle.kts

@@ -23,6 +23,13 @@ kotlin {
             implementation(kotlin("test"))
             implementation(baseLibs.kotlinx.coroutines.test)
         }
+        jvmTest.dependencies {
+            implementation(baseLibs.jetbrains.compose.runtime)
+            implementation(baseLibs.jetbrains.compose.ui)
+            implementation(baseLibs.jetbrains.compose.foundation)
+            implementation(baseLibs.jetbrains.compose.ui.test)
+            implementation(compose.desktop.currentOs)
+        }
     }
 }
 

multiplatform-markdown-renderer/src/jvmTest/kotlin/com/mikepenz/markdown/compose/elements/DetachedPlacementTest.kt

@@ -0,0 +1,61 @@
+package com.mikepenz.markdown.compose.elements
+
+import androidx.compose.foundation.ExperimentalFoundationApi
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.pager.HorizontalPager
+import androidx.compose.foundation.pager.rememberPagerState
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.text.TextLinkStyles
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.test.ExperimentalTestApi
+import androidx.compose.ui.test.runComposeUiTest
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.test.swipeRight
+import androidx.compose.ui.test.swipeLeft
+import androidx.compose.ui.test.swipeDown
+import androidx.compose.ui.test.swipeUp
+import androidx.compose.ui.test.performTouchInput
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.compose.ui.platform.testTag
+import com.mikepenz.markdown.compose.Markdown
+import com.mikepenz.markdown.model.DefaultMarkdownColors
+import com.mikepenz.markdown.model.DefaultMarkdownTypography
+import kotlin.test.Test
+
+/**
+ * Regression test for #639: `onPlaced` read `parentLayoutCoordinates` on detached coordinates
+ * while lazy items / pager pages were recycled, throwing `IllegalStateException`.
+ */
+@OptIn(ExperimentalTestApi::class, ExperimentalFoundationApi::class)
+class DetachedPlacementTest {
+    private val colors = DefaultMarkdownColors(Color.Black, Color.LightGray, Color.LightGray, Color.Gray, Color.White)
+    private val style = TextStyle.Default
+    private val typography = DefaultMarkdownTypography(
+        style, style, style, style, style, style, style, style, style, style, style, style, style, style,
+        TextLinkStyles(), style,
+    )
+    private val content = "Some **bold** text and a [link](https://example.com) to recycle."
+
+    @Test
+    fun pagerWithLazyMarkdownSurvivesRecycling() = runComposeUiTest {
+        setContent {
+            HorizontalPager(rememberPagerState { 2 }, Modifier.fillMaxSize().testTag("pager")) { page ->
+                LazyColumn(Modifier.fillMaxSize().testTag("list$page")) {
+                    items(200) { Markdown(content, colors, typography, Modifier.height(48.dp), immediate = true) }
+                }
+            }
+        }
+        repeat(3) {
+            // recycle lazy items on the visible page, then swipe to the other page and back
+            repeat(5) { onNodeWithTag("pager").performTouchInput { swipeUp() } }
+            onNodeWithTag("pager").performTouchInput { swipeLeft() }
+            waitForIdle()
+            repeat(5) { onNodeWithTag("pager").performTouchInput { swipeDown() } }
+            onNodeWithTag("pager").performTouchInput { swipeRight() }
+            waitForIdle()
+        }
+    }
+}