Mobile — Snapshot / Visual Regression Testing

Snapshot testing renders UI to images and compares to known-good baselines. It's the cheapest way to catch unintended visual regressions. Per-platform tools dominate; Compose Multiplatform and RN have a thinner ecosystem here. For non-visual testing see Mobile — Testing Frameworks.

iOS / SwiftUI

• ★ swift-snapshot-testing (Point-Free) — the de-facto Swift snapshot tool; renders SwiftUI / UIKit / images / text / JSON. MIT.
• iOSSnapshotTestCase — Facebook's older library; less hot.
• SnapshotPreviews (EmergeTools) — automatic snapshots from #Preview macros; free + paid tier.

Android / Compose

• ★ Paparazzi (Square) — render Compose to PNG on the JVM (no device); fast feedback. Apache 2.0.
• ★ Roborazzi — Robolectric-based snapshot testing; works with Compose; supports interaction recording. Free.
• Shot (Karumi) — older instrumented snapshot library.
• Showkase — catalog of all your @Preview composables; not snapshotting per se but pairs well.

React Native

• Jest + react-test-renderer — snapshot the React tree (text-shaped, not pixel).
• Loki — visual snapshot for React Native via Storybook.
• Storybook for RN + Chromatic — paid; visual diff hosted.
• react-native-owl — pixel snapshot tool.

Flutter

• ★ flutter_test golden tests — built-in; matchesGoldenFile.
• golden_toolkit — better defaults, font loading, multi-device golden tests.
• alchemist — modern golden testing helper.

Compose Multiplatform / KMP

• Paparazzi — Android JVM only; works on the Android target.
• For iOS snapshots in CMP, use swift-snapshot-testing on the iOS app target.
• Cross-platform CMP visual tests are an open gap as of 2026.

Visual regression hosted services

• Chromatic — Storybook visual testing; works with Storybook for RN. Paid.
• Argos — open-source visual diff service; free OSS + paid hosted.
• Percy (BrowserStack) — paid.
• Lost Pixel — open-source visual regression CI.
• Emerge Tools — iOS / Android perf + size + snapshot platform; paid.

What snapshots catch (and don't)

• Catch: layout regressions, theming bugs, font/locale issues, accessibility-tree changes.
• Miss: animation correctness, timing-dependent UI, real input/gesture behavior. Pair with Maestro.

Tips

• Render at multiple device sizes / locales to catch RTL and small-screen bugs.
• Render in light + dark + high-contrast to catch theming gaps.
• Use deterministic data and frozen clocks — randomness ruins snapshots.
• Commit baselines to the repo; review diffs in PRs.

Pick this if…

• iOS/SwiftUI: swift-snapshot-testing.
• Android/Compose: Paparazzi for fastest feedback; Roborazzi if you need interaction.
• Flutter: golden_toolkit or alchemist on top of flutter_test.
• RN with Storybook: Loki or Chromatic.
• Need a hosted UI for diffs: Chromatic, Argos, or Lost Pixel.
• iOS-Android per-platform parity matters: run Paparazzi + swift-snapshot-testing on the same screen specs.