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Test: Let the remembered TextFieldState render test take up to four frames #88

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Merged
b-re-w merged 1 commit into from
Oct 3, 2026
Merged

Test: Let the remembered TextFieldState render test take up to four frames #88

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22 changes: 18 additions & 4 deletions ksp-fixtures/compose/src/desktopTest/kotlin/fixture/compose/TextFieldStateRenderTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -138,7 +138,8 @@ class TextFieldStateRenderTest {
PythonComposition(REMEMBERED)
}
val before: IntArray
val after: IntArray
var after: IntArray
var frames = 0
try {
before = pixelsOf(scene.render())
Python3.exec(
Expand All @@ -148,8 +149,18 @@ class TextFieldStateRenderTest {
_tfs_seen[0].setTextAndPlaceCursorAtEnd('a much longer line of text')
""".trimIndent(),
)
Snapshot.sendApplyNotifications()
after = pixelsOf(scene.render())
// `TextField(state=...)` does not finish reacting to a state write inside one frame: the
// text-changed handling of BasicTextField runs on the scene's coroutine dispatcher, which is
// flushed by `render()`, so the pixels can trail the write by a frame. The test is the frame
// clock (there is none), so it advances it explicitly -- but only up to MAX_FRAMES, and it
// stops at the first frame that differs. A write that truly never reaches the draw leaves every
// one of these frames identical to `before`, and the assertion below still fails.
after = before
while (frames < MAX_FRAMES && differing(before, after) <= 10) {
Snapshot.sendApplyNotifications()
after = pixelsOf(scene.render())
frames++
}
Python3.exec(
"""
assert all(_s.text == 'a much longer line of text' for _s in _tfs_seen), \
Expand All @@ -160,7 +171,7 @@ class TextFieldStateRenderTest {
scene.close()
}
val moved = differing(before, after)
println("compose rememberTextFieldState: ink ${inkOf(before)} -> ${inkOf(after)} px, $moved pixels differ")
println("compose rememberTextFieldState: ink ${inkOf(before)} -> ${inkOf(after)} px, $moved pixels differ after $frames frame(s)")
assertTrue(inkOf(before) > 0, "TextField(state=rememberTextFieldState(...)) never composed")
assertTrue(moved > 10, "only $moved pixels differ, so the write from Python never reached the next frame")
}
Expand Down Expand Up @@ -198,6 +209,9 @@ class TextFieldStateRenderTest {
const val FIELD_WIDTH = 280
const val FIELD_HEIGHT = 64

/** Upper bound on frames rendered after the write in the remembered-state test. */
const val MAX_FRAMES = 4

val REMEMBERED = """
from androidx.compose.foundation.text.input import rememberTextFieldState
from androidx.compose.material3 import TextField
Expand Down
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