[TextField Selection] Drag Handle.

Bug: 139311556
Test: Manually tested.
Test: ./gradlew :ui:ui-text:testDebugUnitTest
Test: ./gradlew :ui:ui-core:testDebugUnitTest

RelNote: Implement Drag Selection Handles to change selection for TextField.

Change-Id: I27032ee670131726d579612591dafcf3d60680b6

diff --git a/ui/ui-text/src/test/kotlin/androidx/ui/text/selection/TextFieldSelectionManagerTest.kt b/ui/ui-text/src/test/kotlin/androidx/ui/text/selection/TextFieldSelectionManagerTest.kt
index ea7997c..7ed0c43 100644
--- a/ui/ui-text/src/test/kotlin/androidx/ui/text/selection/TextFieldSelectionManagerTest.kt
+++ b/ui/ui-text/src/test/kotlin/androidx/ui/text/selection/TextFieldSelectionManagerTest.kt

@@ -59,8 +59,8 @@
     private val dragBeginPosition = Offset.Zero
     private val dragDistance = Offset(300f, 15f)
     private val beginOffset = 0
-    private val dragOffset = text.indexOf('W')
-    private val longPressTextRange = TextRange(0, "Hello".length)
+    private val dragOffset = text.indexOf('r')
+    private val fakeTextRange = TextRange(0, "Hello".length)
     private val dragTextRange = TextRange("Hello".length + 1, text.length)
 
     private val manager = TextFieldSelectionManager()
@@ -96,7 +96,7 @@
             beginOffset
         )
         whenever(state.layoutResult!!.getOffsetForPosition(dragDistance)).thenReturn(dragOffset)
-        whenever(state.layoutResult!!.getWordBoundary(beginOffset)).thenReturn(longPressTextRange)
+        whenever(state.layoutResult!!.getWordBoundary(beginOffset)).thenReturn(fakeTextRange)
         whenever(state.layoutResult!!.getWordBoundary(dragOffset)).thenReturn(dragTextRange)
         whenever(state.layoutResult!!.getBidiRunDirection(any()))
             .thenReturn(ResolvedTextDirection.Ltr)
@@ -115,7 +115,7 @@
         manager.longPressDragObserver.onLongPress(dragBeginPosition)
 
         assertThat(state.selectionIsOn).isTrue()
-        assertThat(value.selection).isEqualTo(longPressTextRange)
+        assertThat(value.selection).isEqualTo(fakeTextRange)
         verify(
             hapticFeedback,
             times(1)
@@ -135,6 +135,72 @@
     }
 
     @Test
+    fun TextFieldSelectionManager_handleDragObserver_onStart_startHandle() {
+        manager.handleDragObserver(isStartHandle = true).onStart(Offset.Zero)
+
+        assertThat(state.draggingHandle).isTrue()
+        verify(spyLambda, times(0)).invoke(any())
+        verify(
+            hapticFeedback,
+            times(0)
+        ).performHapticFeedback(HapticFeedbackType.TextHandleMove)
+    }
+
+    @Test
+    fun TextFieldSelectionManager_handleDragObserver_onStart_endHandle() {
+        manager.handleDragObserver(isStartHandle = false).onStart(Offset.Zero)
+
+        assertThat(state.draggingHandle).isTrue()
+        verify(spyLambda, times(0)).invoke(any())
+        verify(
+            hapticFeedback,
+            times(0)
+        ).performHapticFeedback(HapticFeedbackType.TextHandleMove)
+    }
+
+    @Test
+    fun TextFieldSelectionManager_handleDragObserver_onDrag_startHandle() {
+        manager.value = TextFieldValue(text = text, selection = TextRange(0, "Hello".length))
+
+        val result = manager.handleDragObserver(isStartHandle = true).onDrag(dragDistance)
+
+        assertThat(result).isEqualTo(dragDistance)
+        assertThat(value.selection).isEqualTo(TextRange(dragOffset, "Hello".length))
+        verify(
+            hapticFeedback,
+            times(1)
+        ).performHapticFeedback(HapticFeedbackType.TextHandleMove)
+    }
+
+    @Test
+    fun TextFieldSelectionManager_handleDragObserver_onDrag_endHandle() {
+        manager.value = TextFieldValue(text = text, selection = TextRange(0, "Hello".length))
+
+        val result = manager.handleDragObserver(isStartHandle = false).onDrag(dragDistance)
+
+        assertThat(result).isEqualTo(dragDistance)
+        assertThat(value.selection).isEqualTo(TextRange(0, dragOffset))
+        verify(
+            hapticFeedback,
+            times(1)
+        ).performHapticFeedback(HapticFeedbackType.TextHandleMove)
+    }
+
+    @Test
+    fun TextFieldSelectionManager_handleDragObserver_onStop() {
+        manager.handleDragObserver(false).onStart(Offset.Zero)
+        manager.handleDragObserver(false).onDrag(Offset.Zero)
+
+        manager.handleDragObserver(false).onStop(Offset.Zero)
+
+        assertThat(state.draggingHandle).isFalse()
+        verify(
+            hapticFeedback,
+            times(0)
+        ).performHapticFeedback(HapticFeedbackType.TextHandleMove)
+    }
+
+    @Test
     fun copy_selection_collapse() {
         manager.value = TextFieldValue(text = text, selection = TextRange(4, 4))
 
@@ -200,7 +266,8 @@
     fun cut_selection_not_null() {
         manager.value = TextFieldValue(
             text = text + text,
-            selection = TextRange("Hello".length, text.length))
+            selection = TextRange("Hello".length, text.length)
+        )
 
         manager.cut()