Merge branch 'sidecar-adb-and-ime' into trial-merge

sidecar/src/main/kotlin/dev/sanderling/sidecar/DriverBackend.kt

@@ -937,6 +937,90 @@ internal fun treeWithoutKeyboard(
     return current
 }
 
+// SELECT_ALL_COMMAND selects the focused field's whole content with
+// CTRL+A (keycodes 113 and 29) and DELETE_KEY_COMMAND then deletes the
+// selection (keycode 67). Two key events, whatever the field holds.
+internal const val SELECT_ALL_COMMAND = "input keycombination 113 29"
+internal const val DELETE_KEY_COMMAND = "input keyevent 67"
+
+// DELETE_BATCH_KEYS bounds how many deletes ride in one `input keyevent`
+// invocation on the fallback path. `input` takes a list of keycodes, so the
+// round trip is paid per batch rather than per character: measured 2.3 ms/char
+// against the 29.6 ms/char of one round trip each.
+internal const val DELETE_BATCH_KEYS = 200
+
+internal fun deleteKeyCommands(count: Int, batch: Int): List<String> {
+    if (count <= 0) return emptyList()
+    val size = batch.coerceAtLeast(1)
+    return (0 until count).chunked(size).map { chunk ->
+        chunk.joinToString(" ", prefix = "input keyevent ") { "67" }
+    }
+}
+
+// focusedEditableTextLength reports how much text the focused text field
+// holds, or null when the tree names no focused text field. Null is "cannot
+// tell", which is not the same as empty and must not be read as it.
+//
+// The field is found by class, not by an "editable" attribute: maestro's tree
+// carries no such attribute. Class also settles the trap an open keyboard
+// sets, which is that the IME contributes a focused node of its own. That node
+// holds no text, so taking the first focused node would read a field still
+// holding 4096 characters as empty, and empty is the answer that stops the
+// erase.
+internal fun focusedEditableTextLength(treeJson: String): Int? {
+    if (treeJson.isBlank()) return null
+    return try {
+        focusedFieldLength(jsonMapper.readTree(treeJson))
+    } catch (_: Exception) {
+        null
+    }
+}
+
+private fun focusedFieldLength(
+    node: com.fasterxml.jackson.databind.JsonNode,
+): Int? {
+    val attributes = node.get("attributes")
+    if (attributes != null && attributes.isObject &&
+        attributes.get("focused")?.asText() == "true" &&
+        attributes.get("class")?.asText().orEmpty().endsWith("EditText")
+    ) {
+        return attributes.get("text")?.asText().orEmpty().length
+    }
+    val children = node.get("children") ?: return null
+    if (!children.isArray) return null
+    for (child in children) focusedFieldLength(child)?.let { return it }
+    return null
+}
+
+// eraseFocusedField clears the field the runner just tapped.
+//
+// maestro's eraseText sends one delete per character through its own
+// instrumentation, which measured 29.6 ms/char on the API 34 emulator: the
+// 4096-character string the corpus types cost ~121s to clear, a fifth of a 20
+// minute budget spent on one step. Selecting the content and deleting the
+// selection costs the same two key events at any length, measured 0.15s to
+// 1.16s for 4096 characters across API 34, 35 and 36.
+//
+// A fast erase that leaves characters behind would be far worse than a slow
+// one, because the next InputText appends to the residue and nothing
+// downstream detects it. So the result is read back off the tree, and a field
+// that is not empty, or that the tree cannot report on at all, is finished off
+// per character. Those deletes ride in batches, so even that path costs one
+// round trip per batch rather than the one per character this replaces.
+internal fun eraseFocusedField(
+    characterCount: Int,
+    shell: (String) -> Unit,
+    focusedTextLength: () -> Int?,
+) {
+    if (characterCount <= 0) return
+    shell(SELECT_ALL_COMMAND)
+    shell(DELETE_KEY_COMMAND)
+    if (focusedTextLength() == 0) return
+    for (command in deleteKeyCommands(characterCount, DELETE_BATCH_KEYS)) {
+        shell(command)
+    }
+}
+
 // typingOwner picks what the mid-type foreground guard holds later reads
 // against. A dumpsys it could read names the resumed package, and that is the
 // answer.
@@ -1131,8 +1215,11 @@ class MaestroDriverBackend(private val serial: String?) : DriverBackend {
     private fun foregroundPackage(): String? =
         parseResumedPackage(foregroundDumpsys())
 
-    override fun eraseText(characterCount: Int) =
-        driver.eraseText(characterCount)
+    override fun eraseText(characterCount: Int) = eraseFocusedField(
+        characterCount,
+        shell = { dadb.shell(it) },
+        focusedTextLength = { focusedEditableTextLength(hierarchy()) },
+    )
 
     override fun swipe(
         fromX: Int,

sidecar/src/test/kotlin/dev/sanderling/sidecar/EraseTextTest.kt

@@ -0,0 +1,128 @@
+package dev.sanderling.sidecar
+
+import org.junit.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class EraseTextTest {
+
+    // maestro's eraseText sends one delete per character through its
+    // instrumentation, measured at 29.6 ms/char on the API 34 emulator: the
+    // 4096-character string the corpus types cost ~121s to clear, a fifth of a
+    // 20 minute run for one step. Selecting the field and deleting the
+    // selection is the same two key events whatever the field holds.
+    @Test fun aClearedFieldCostsTwoKeyEventsWhateverItsLength() {
+        for (length in listOf(1, 21, 512, 4096)) {
+            val sent = mutableListOf<String>()
+            eraseFocusedField(length, { sent.add(it) }) { 0 }
+            assertEquals(
+                listOf(SELECT_ALL_COMMAND, DELETE_KEY_COMMAND),
+                sent,
+                "length $length must not scale the erase",
+            )
+        }
+    }
+
+    // The dangerous failure is a fast erase that leaves characters behind: the
+    // next InputText appends to the residue and every reading downstream is
+    // wrong with nothing to catch it. A field the select-all did not clear is
+    // finished off per character rather than assumed empty.
+    @Test fun aFieldTheSelectAllMissedIsFinishedOffPerCharacter() {
+        val sent = mutableListOf<String>()
+        eraseFocusedField(4096, { sent.add(it) }) { 4096 }
+
+        assertEquals(SELECT_ALL_COMMAND, sent.first())
+        assertEquals(DELETE_KEY_COMMAND, sent[1])
+        assertEquals(
+            4096,
+            sent.drop(2).sumOf { command ->
+                command.removePrefix("input keyevent ").split(" ").size
+            },
+            "every character must still be deleted",
+        )
+    }
+
+    // Unknown is not empty. A tree that cannot name the focused field is no
+    // evidence the erase worked, and the safe way to be wrong is the delete
+    // that costs time rather than the one that leaves residue.
+    @Test fun aFieldThatCannotBeReadIsFinishedOffRatherThanAssumedEmpty() {
+        val sent = mutableListOf<String>()
+        eraseFocusedField(8, { sent.add(it) }) { null }
+        assertTrue(sent.size > 2, "an unverified erase must not stop at two")
+    }
+
+    @Test fun nothingToEraseIssuesNoKeysAtAll() {
+        val sent = mutableListOf<String>()
+        eraseFocusedField(0, { sent.add(it) }) { 0 }
+        eraseFocusedField(-1, { sent.add(it) }) { 0 }
+        assertEquals(emptyList(), sent)
+    }
+
+    // Batching is what keeps the fallback affordable: one round trip per batch
+    // rather than one per character, measured 2.3 ms/char against maestro's
+    // 29.6. The count must survive the batching exactly.
+    @Test fun deleteKeyCommandsBatchesWithoutLosingACharacter() {
+        for (count in listOf(1, 199, 200, 201, 4096)) {
+            val commands = deleteKeyCommands(count, DELETE_BATCH_KEYS)
+            val keys = commands.flatMap {
+                it.removePrefix("input keyevent ").split(" ")
+            }
+            assertEquals(count, keys.size, "count $count")
+            assertTrue(keys.all { it == "67" }, "only KEYCODE_DEL")
+            assertTrue(
+                commands.size <= (count + DELETE_BATCH_KEYS - 1) /
+                    DELETE_BATCH_KEYS,
+                "count $count used ${commands.size} round trips",
+            )
+        }
+    }
+
+    // The erase targets the field the runner just tapped, so the length that
+    // decides whether it worked is that field's, not some other field that
+    // legitimately still holds text.
+    //
+    // The tree these fixtures copy is the one the device really returns, and
+    // it holds the trap: an open keyboard puts a SECOND focused node in the
+    // tree, one of the IME's own keys, and it carries no text. Reading the
+    // first focused node would call a field that still holds 4096 characters
+    // empty, which is the one wrong answer that matters here. maestro's tree
+    // also carries no "editable" attribute at all, so the text field has to be
+    // recognised by its class.
+    @Test fun theFocusedFieldIsReadPastTheKeyboardsOwnFocusedKey() {
+        assertEquals(4096, focusedEditableTextLength(TREE_WITH_FULL_FIELD))
+        assertEquals(0, focusedEditableTextLength(TREE_WITH_EMPTY_FIELD))
+    }
+
+    @Test fun aTreeWithNoFocusedFieldReadsAsUnknown() {
+        assertEquals(null, focusedEditableTextLength(TREE_WITH_NO_FOCUS))
+        assertEquals(null, focusedEditableTextLength(""))
+        assertEquals(null, focusedEditableTextLength("not json"))
+    }
+}
+
+// The keyboard's own focused key, exactly as the device reports it: focused,
+// no text, and not a text field.
+private val IME_FOCUSED_KEY =
+    """
+    {"attributes":{"text":"","resource-id":
+     "com.google.android.inputmethod.latin:id/key_pos_header_access",
+     "focused":"true","class":"android.widget.FrameLayout"},"children":[]}
+    """.trimIndent()
+
+private fun tree(focusedText: String?, otherText: String): String {
+    val field = focusedText?.let {
+        """,{"attributes":{"resource-id":"AccountNameField","focused":"true",
+           "class":"android.widget.EditText","text":"$it"},"children":[]}"""
+    } ?: ""
+    return """
+    {"attributes":{"resource-id":"AddAccountScreen"},"children":[
+      $IME_FOCUSED_KEY $field,
+      {"attributes":{"resource-id":"OtherField","focused":"false",
+       "class":"android.widget.EditText","text":"$otherText"},
+       "children":[]}]}
+    """.trimIndent()
+}
+
+private val TREE_WITH_FULL_FIELD = tree("a".repeat(4096), "keep me")
+private val TREE_WITH_EMPTY_FIELD = tree("", "keep me")
+private val TREE_WITH_NO_FOCUS = tree(null, "keep me")