Add JVM lazy clipboard verification tests

app/src/desktopTest/kotlin/com/crosspaste/paste/JvmLazyClipboardTest.kt

@@ -0,0 +1,287 @@
+package com.crosspaste.paste
+
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.condition.EnabledIf
+import org.junit.jupiter.api.condition.EnabledOnOs
+import org.junit.jupiter.api.condition.OS
+import java.awt.GraphicsEnvironment
+import java.awt.Toolkit
+import java.awt.datatransfer.ClipboardOwner
+import java.awt.datatransfer.DataFlavor
+import java.awt.datatransfer.StringSelection
+import java.awt.datatransfer.Transferable
+import java.awt.datatransfer.UnsupportedFlavorException
+import java.io.File
+import java.util.concurrent.atomic.AtomicBoolean
+import java.util.concurrent.atomic.AtomicInteger
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+@EnabledIf("isNotHeadless")
+class JvmLazyClipboardTest {
+
+    companion object {
+        @JvmStatic
+        fun isNotHeadless(): Boolean = !GraphicsEnvironment.isHeadless()
+    }
+
+    private val systemClipboard by lazy { Toolkit.getDefaultToolkit().systemClipboard }
+
+    private val noOpOwner = ClipboardOwner { _, _ -> }
+
+    private fun cleanupClipboard() {
+        try {
+            systemClipboard.setContents(StringSelection(""), noOpOwner)
+        } catch (_: Exception) {
+            // best-effort cleanup
+        }
+    }
+
+    private fun trackingStringTransferable(called: AtomicBoolean): Transferable =
+        object : Transferable {
+            override fun getTransferDataFlavors(): Array<DataFlavor> = arrayOf(DataFlavor.stringFlavor)
+
+            override fun isDataFlavorSupported(flavor: DataFlavor): Boolean = flavor == DataFlavor.stringFlavor
+
+            override fun getTransferData(flavor: DataFlavor): Any {
+                if (flavor == DataFlavor.stringFlavor) {
+                    called.set(true)
+                    return "test string"
+                }
+                throw UnsupportedFlavorException(flavor)
+            }
+        }
+
+    private fun trackingFileListTransferable(called: AtomicBoolean): Transferable =
+        object : Transferable {
+            override fun getTransferDataFlavors(): Array<DataFlavor> = arrayOf(DataFlavor.javaFileListFlavor)
+
+            override fun isDataFlavorSupported(flavor: DataFlavor): Boolean = flavor == DataFlavor.javaFileListFlavor
+
+            override fun getTransferData(flavor: DataFlavor): Any {
+                if (flavor == DataFlavor.javaFileListFlavor) {
+                    called.set(true)
+                    return emptyList<File>()
+                }
+                throw UnsupportedFlavorException(flavor)
+            }
+        }
+
+    private fun trackingMultiFlavorTransferable(
+        advertisedFlavors: Array<DataFlavor>,
+        callCount: AtomicInteger,
+    ): Transferable =
+        object : Transferable {
+            override fun getTransferDataFlavors(): Array<DataFlavor> = advertisedFlavors
+
+            override fun isDataFlavorSupported(flavor: DataFlavor): Boolean = flavor in advertisedFlavors
+
+            override fun getTransferData(flavor: DataFlavor): Any {
+                if (flavor in advertisedFlavors) {
+                    callCount.incrementAndGet()
+                    return if (flavor == DataFlavor.stringFlavor) "plain text" else "<b>html</b>"
+                }
+                throw UnsupportedFlavorException(flavor)
+            }
+        }
+
+    private fun ownerLostTransferable(): Transferable =
+        object : Transferable {
+            override fun getTransferDataFlavors(): Array<DataFlavor> = arrayOf(DataFlavor.stringFlavor)
+
+            override fun isDataFlavorSupported(flavor: DataFlavor): Boolean = flavor == DataFlavor.stringFlavor
+
+            override fun getTransferData(flavor: DataFlavor): Any {
+                if (flavor == DataFlavor.stringFlavor) return "original"
+                throw UnsupportedFlavorException(flavor)
+            }
+        }
+
+    @Nested
+    @EnabledOnOs(OS.MAC)
+    inner class MacosEagerClipboardTests {
+
+        @Test
+        fun `setContents triggers immediate getTransferData for string flavor`() {
+            val called = AtomicBoolean(false)
+            try {
+                systemClipboard.setContents(trackingStringTransferable(called), noOpOwner)
+                assertTrue(called.get(), "getTransferData should be called eagerly during setContents on macOS")
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `setContents triggers immediate getTransferData for file list flavor`() {
+            val called = AtomicBoolean(false)
+            try {
+                systemClipboard.setContents(trackingFileListTransferable(called), noOpOwner)
+                assertTrue(called.get(), "getTransferData should be called eagerly during setContents on macOS")
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `setContents triggers immediate getTransferData for all advertised flavors`() {
+            val htmlFlavor = DataFlavor("text/html;class=java.lang.String")
+            val advertisedFlavors = arrayOf(DataFlavor.stringFlavor, htmlFlavor)
+            val callCount = AtomicInteger(0)
+            try {
+                systemClipboard.setContents(
+                    trackingMultiFlavorTransferable(advertisedFlavors, callCount),
+                    noOpOwner,
+                )
+                assertTrue(
+                    callCount.get() >= advertisedFlavors.size,
+                    "getTransferData should be called at least once per advertised flavor on macOS, " +
+                        "but was called ${callCount.get()} times for ${advertisedFlavors.size} flavors",
+                )
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `clipboard data persists after owner lost`() {
+            try {
+                systemClipboard.setContents(ownerLostTransferable(), noOpOwner)
+                systemClipboard.setContents(StringSelection("other"), noOpOwner)
+                val contents = systemClipboard.getData(DataFlavor.stringFlavor) as String
+                assertEquals("other", contents, "Clipboard should contain the new value after owner change")
+            } finally {
+                cleanupClipboard()
+            }
+        }
+    }
+
+    @Nested
+    @EnabledOnOs(OS.WINDOWS)
+    inner class WindowsEagerClipboardTests {
+
+        @Test
+        fun `setContents triggers immediate getTransferData for string flavor`() {
+            val called = AtomicBoolean(false)
+            try {
+                systemClipboard.setContents(trackingStringTransferable(called), noOpOwner)
+                assertTrue(called.get(), "getTransferData should be called eagerly during setContents on Windows")
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `setContents triggers immediate getTransferData for file list flavor`() {
+            val called = AtomicBoolean(false)
+            try {
+                systemClipboard.setContents(trackingFileListTransferable(called), noOpOwner)
+                assertTrue(called.get(), "getTransferData should be called eagerly during setContents on Windows")
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `setContents triggers immediate getTransferData for all advertised flavors`() {
+            val htmlFlavor = DataFlavor("text/html;class=java.lang.String")
+            val advertisedFlavors = arrayOf(DataFlavor.stringFlavor, htmlFlavor)
+            val callCount = AtomicInteger(0)
+            try {
+                systemClipboard.setContents(
+                    trackingMultiFlavorTransferable(advertisedFlavors, callCount),
+                    noOpOwner,
+                )
+                assertTrue(
+                    callCount.get() >= advertisedFlavors.size,
+                    "getTransferData should be called at least once per advertised flavor on Windows, " +
+                        "but was called ${callCount.get()} times for ${advertisedFlavors.size} flavors",
+                )
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `clipboard data persists after owner lost`() {
+            try {
+                systemClipboard.setContents(ownerLostTransferable(), noOpOwner)
+                systemClipboard.setContents(StringSelection("other"), noOpOwner)
+                val contents = systemClipboard.getData(DataFlavor.stringFlavor) as String
+                assertEquals("other", contents, "Clipboard should contain the new value after owner change")
+            } finally {
+                cleanupClipboard()
+            }
+        }
+    }
+
+    @Nested
+    @EnabledOnOs(OS.LINUX)
+    inner class LinuxLazyClipboardTests {
+
+        @Test
+        fun `setContents does not trigger immediate getTransferData for string flavor`() {
+            val called = AtomicBoolean(false)
+            try {
+                systemClipboard.setContents(trackingStringTransferable(called), noOpOwner)
+                assertFalse(
+                    called.get(),
+                    "getTransferData should NOT be called during setContents on Linux (lazy clipboard)",
+                )
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `setContents does not trigger immediate getTransferData for file list flavor`() {
+            val called = AtomicBoolean(false)
+            try {
+                systemClipboard.setContents(trackingFileListTransferable(called), noOpOwner)
+                assertFalse(
+                    called.get(),
+                    "getTransferData should NOT be called during setContents on Linux (lazy clipboard)",
+                )
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `setContents does not trigger getTransferData for any advertised flavor`() {
+            val htmlFlavor = DataFlavor("text/html;class=java.lang.String")
+            val advertisedFlavors = arrayOf(DataFlavor.stringFlavor, htmlFlavor)
+            val callCount = AtomicInteger(0)
+            try {
+                systemClipboard.setContents(
+                    trackingMultiFlavorTransferable(advertisedFlavors, callCount),
+                    noOpOwner,
+                )
+                assertEquals(
+                    0,
+                    callCount.get(),
+                    "getTransferData should NOT be called during setContents on Linux, " +
+                        "but was called ${callCount.get()} times",
+                )
+            } finally {
+                cleanupClipboard()
+            }
+        }
+
+        @Test
+        fun `getTransferData is called lazily on paste request`() {
+            val called = AtomicBoolean(false)
+            try {
+                systemClipboard.setContents(trackingStringTransferable(called), noOpOwner)
+                assertFalse(called.get(), "getTransferData should not be called yet")
+                // Trigger a paste request by reading from clipboard
+                systemClipboard.getData(DataFlavor.stringFlavor)
+                assertTrue(called.get(), "getTransferData should be called on paste request")
+            } finally {
+                cleanupClipboard()
+            }
+        }
+    }
+}