Use this skill to verify Compose layout measurements from a UI test using `assertWidthIsEqualTo`, `assertHeightIsEqualTo`, `assertWidthIsAtLeast`, `assertHeightIsAtLeast`, `assertTouchWidthIsEqualTo`, `assertTouchHeightIsEqualTo`, `assertPositionInRootIsEqualTo`, `assertTopPositionInRootIsEqualTo`, `assertLeftPositionInRootIsEqualTo`, plus read helpers `getUnclippedBoundsInRoot`, `getBoundsInRoot`, `getAlignmentLinePosition`, `getFirstLinkBounds`, and the underlying `Dp.assertIsEqualTo(expected, subject, tolerance = Dp(.5f))`. Covers the half-dp default tolerance, the unclipped vs clipped distinction, the canonical "compute padding from two unclipped rects" pattern, and minimum-touch-target assertions like `assertHeightIsAtLeast(MinHeight + 1.dp)`. Use when the developer wants to assert sizes, padding, alignment, position in dp, or asks about `getUnclippedBoundsInRoot`, `DpRect`, touch-target size, or compares widths in pixels. If the developer is comparing layout dimensions from a test, use this skill.
Use this skill to verify Compose layout measurements from a UI test using `assertWidthIsEqualTo`, `assertHeightIsEqualTo`, `assertWidthIsAtLeast`, `assertHeightIsAtLeast`, `assertTouchWidthIsEqualTo`, `assertTouchHeightIsEqualTo`, `assertPositionInRootIsEqualTo`, `assertTopPositionInRootIsEqualTo`, `assertLeftPositionInRootIsEqualTo`, plus read helpers `getUnclippedBoundsInRoot`, `getBoundsInRoot`, `getAlignmentLinePosition`, `getFirstLinkBounds`, and the underlying `Dp.assertIsEqualTo(expected, subject, tolerance = Dp(.5f))`. Covers the half-dp default tolerance, the unclipped vs clipped distinction, the canonical "compute padding from two unclipped rects" pattern, and minimum-touch-target assertions like `assertHeightIsAtLeast(MinHeight + 1.dp)`. Use when the developer wants to assert sizes, padding, alignment, position in dp, or asks about `getUnclippedBoundsInRoot`, `DpRect`, touch-target size, or compares widths in pixels. If the developer is comparing layout dimensions from a test, use this skill.
license
Apache-2.0. See LICENSE for complete terms.
metadata
{"author":"Jaewoong Eum (skydoves)","keywords":["jetpack-compose","ui-testing","assertWidthIsEqualTo","assertHeightIsAtLeast","assertPositionInRootIsEqualTo","getUnclippedBoundsInRoot","DpRect","touch-target","dp-tolerance","layout-assertions"]}
Asserting Bounds and Dimensions — Layout Math in Dp, Not Pixels
Layout assertions belong in dp, run with a half-dp tolerance, and most of the interesting checks (padding, gap, alignment) are subtractions between two getUnclippedBoundsInRoot() rectangles. This skill picks the right size/position assertion, explains clipped vs unclipped, and shows the canonical "compute padding from two rects" pattern lifted directly from material3/ButtonTest.kt.
When to use this skill
The developer wants to verify a Button is 48 dp tall, a Spacer is 16 dp wide, an Icon is at position (24.dp, 12.dp).
The developer asks how to assert the padding between two composables.
The developer asks about minimum touch target sizes (ChipDefaults.MinHeight + 1.dp).
The developer is comparing layout values in pixels and wants the dp-typed equivalent.
The developer mentions assertWidthIsEqualTo, getUnclippedBoundsInRoot, DpRect, getAlignmentLinePosition, getFirstLinkBounds.
When NOT to use this skill
The check is about state (enabled, on, selected) — see ./asserting-node-state-and-text/SKILL.md.
The check is "is the node on screen at all" — assertIsDisplayed() is enough; bounds math adds friction without value.
The composable's bounds depend on an animation in flight — pause the clock first; see ../../synchronization/testing-animations-deterministically/SKILL.md.
The bounds are relative to a screenshot — use a screenshot test instead.
Prerequisites
A working ComposeTestRule / ComposeUiTest. See ../../setup/configuring-test-dependencies/SKILL.md.
The target composable has finished measuring and placing. If it animates in, advance the test clock first — see ../../synchronization/controlling-the-test-clock/SKILL.md.
For touch-target assertions, the target node has a click action so touchBoundsInRoot is meaningful.
Workflow
1. Pick the assertion by question type. All APIs live in commonMain/.../BoundsAssertions.kt.
2. Use unclipped bounds for layout math; clipped bounds for "what the user sees".getUnclippedBoundsInRoot() returns the laid-out rectangle ignoring viewport clipping (BoundsAssertions.kt:148-152 → unclippedBoundsInRoot private, BoundsAssertions.kt:284-291). getBoundsInRoot() clips to the viewport (BoundsAssertions.kt:158-165). Padding/spacing math uses unclipped; partial-visibility checks use clipped.
3. Tolerance is half a dp by default.Dp.assertIsEqualTo(expected, subject, tolerance = Dp(.5f)) (BoundsAssertions.kt:319) accepts deviations up to 0.5 dp because layout rounding introduces sub-dp drift. Override only when stricter precision is justified by an explicit measurement contract.
4. Compute padding by subtracting two unclipped rects, then call Dp.assertIsEqualTo. This is the canonical material3 pattern (material3/.../ButtonTest.kt:213-225):
val buttonBounds = rule.onNodeWithTag(ButtonTestTag).getUnclippedBoundsInRoot()
val textBounds = rule.onNodeWithTag(TextTestTag).getUnclippedBoundsInRoot()
(textBounds.left - buttonBounds.left).assertIsEqualTo(
24.dp,
"padding between the start of the button and the start of the text.",
)
(buttonBounds.right - textBounds.right).assertIsEqualTo(
24.dp,
"padding between the end of the text and the end of the button.",
)
buttonBounds.height.assertIsEqualTo(ButtonDefaults.MinHeight, "height of button.")
The subject string lands in the failure message: "Actual padding between the start of the button and the start of the text. is 22.dp, expected 24.dp (tolerance: .5.dp)".
5. For minimum-size contracts, use assertHeightIsAtLeast / assertWidthIsAtLeast. Useful when a composable should never be smaller than a constant, even at large font scale. Example from material/ChipTest.kt:226-233:
6. Use touch bounds when verifying tap-target accessibility.assertTouchWidthIsEqualTo / assertTouchHeightIsEqualTo reads node.touchBoundsInRoot (BoundsAssertions.kt:270-282), which can extend past the visual bounds when the composable applies Modifier.minimumInteractiveComponentSize() or similar. Visual bounds use getUnclippedBoundsInRoot; touch bounds answer "where will a click land".
Patterns
Pattern: dp typed assertions over pixel reads
// WRONG@Testfunsubmit_isMin48dpTall() {
rule.setContent { CheckoutScreen() }
val node = rule.onNodeWithTag(SubmitTag).fetchSemanticsNode()
val heightPx = node.size.height
assert(heightPx >= 48 * Resources.getSystem().displayMetrics.density)
}
// WRONG because: pixel-typed and density-dependent. Reads outside the framework's tolerance// model. Failure prints raw integers, no node dump, no subject label.
The merge bypass on the inner Text is the same trick used by material3/ButtonTest.kt:202-226 to keep the inner Text addressable from the merged tree.
Pattern: assertPositionInRootIsEqualTo for absolute placement
// "the close button sits at (320.dp, 0.dp) in the root"
rule.onNodeWithTag(CloseButtonTag)
.assertPositionInRootIsEqualTo(expectedLeft = 320.dp, expectedTop = 0.dp)
If only one axis matters, use assertLeftPositionInRootIsEqualTo / assertTopPositionInRootIsEqualTo to avoid coupling the test to layout decisions on the other axis.
Pattern: alignment line for baseline math
val baselineDp = rule.onNodeWithTag(LabelTag)
.getAlignmentLinePosition(FirstBaseline)
require(!baselineDp.isUnspecified) { "Label has no first baseline" }
baselineDp.assertIsEqualTo(20.dp, "first baseline of label")
getAlignmentLinePosition returns Dp.Unspecified when the alignment line is not provided (BoundsAssertions.kt:172-179). Always check isUnspecified before comparing.
Pattern: tolerance override for sub-dp precision
// Most tests want the default ½ dp tolerance:
rule.onNodeWithTag(IconTag).getUnclippedBoundsInRoot().width.assertIsEqualTo(24.dp, "icon width")
// Stricter tolerance when measuring a hand-aligned constant:val width = rule.onNodeWithTag(IconTag).getUnclippedBoundsInRoot().width
width.assertIsEqualTo(expected = 24.dp, subject = "icon width", tolerance = 0.1.dp)
Pattern: clipped vs unclipped — partial visibility
val unclipped = rule.onNodeWithTag(BannerTag).getUnclippedBoundsInRoot()
val clipped = rule.onNodeWithTag(BannerTag).getBoundsInRoot()
// Banner laid out 200 dp tall but only 80 dp visible (rest clipped by parent):
unclipped.height.assertIsEqualTo(200.dp, "banner intrinsic height")
clipped.height.assertIsEqualTo(80.dp, "banner visible height")
For "is any of it visible", prefer assertIsDisplayed() — see ./asserting-node-state-and-text/SKILL.md.
Mandatory rules
MUST assert in dp using the typed assertWidthIsEqualTo / assertHeightIsEqualTo / assertPositionInRootIsEqualTo. MUST NOT read fetchSemanticsNode().size.width and compare pixels.
MUST use getUnclippedBoundsInRoot() for padding / gap / alignment math; MUST use getBoundsInRoot() only when the contract is "what the user sees after clipping".
MUST pass a meaningful subject string to Dp.assertIsEqualTo so the failure message identifies which measurement failed.
MUST prefer assertHeightIsAtLeast(MinHeight + 1.dp) over assertHeightIsEqualTo(MinHeight + N.dp) when the goal is "the layout grows past the minimum at large font scales".
MUST NOT assume zero tolerance. Layout rounding produces sub-dp drift; rely on the half-dp default and override only when justified.
PREFERRED: when an animation is in flight, pause mainClock.autoAdvance = false and step deterministically before reading bounds. Skydoves hot take #3.
Verification
No node.size.width / node.size.height reads remain. All dimension checks use the typed assert*IsEqualTo / Dp.assertIsEqualTo.
Padding / gap math uses getUnclippedBoundsInRoot; clipped reads only appear with a comment explaining why.
Every Dp.assertIsEqualTo(...) passes a non-empty subject string.
Touch-target assertions use assertTouchWidthIsEqualTo / assertTouchHeightIsEqualTo rather than visual bounds when verifying accessibility constraints.
./gradlew :app:connectedDebugAndroidTest passes; failure messages identify the specific failed measurement by subject.
