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feat(snapshots): Emit diff_threshold in snapshot sidecar (EME-1055) #1158

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runningcode merged 3 commits into from
Apr 21, 2026
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feat(snapshots): Emit diff_threshold in snapshot sidecar (EME-1055) #1158

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4d31af2
feat(snapshots): Emit diff_threshold in snapshot sidecar (EME-1055)
runningcode Apr 21, 2026
c1a5f39
refactor(snapshots): Propagate reflection failures from sidecar writer
runningcode Apr 21, 2026
fea28a3
Revert "refactor(snapshots): Propagate reflection failures from sidec…
runningcode Apr 21, 2026
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
### Features

- Add `@SentrySnapshot` runtime annotation for configuring the per-snapshot diff threshold, published as `io.sentry:sentry-snapshots-runtime` ([EME-1055](https://linear.app/getsentry/issue/EME-1055))
- Emit `diff_threshold` in the snapshot sidecar JSON when a `@Preview` is also annotated with `@SentrySnapshot(diffThreshold = ...)` ([EME-1055](https://linear.app/getsentry/issue/EME-1055))

### Dependencies

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11 changes: 11 additions & 0 deletions plugin-build/src/main/kotlin/io/sentry/android/gradle/snapshot/GenerateSnapshotTestsTask.kt
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Expand Up @@ -376,6 +376,17 @@ class $CLASS_NAME(
if (info.showSystemUi) metadata["show_system_ui"] = true
if (info.showBackground) metadata["show_background"] = true

val diffThreshold: Float? = runCatching {
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@runningcode runningcode Apr 21, 2026

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This catches all errors here in scanning since we are using reflection.

val declaring = Class.forName(preview.declaringClass)
val method = declaring.declaredMethods.firstOrNull { it.name == preview.methodName }
?: return@runCatching null
@Suppress("UNCHECKED_CAST")
val annClass = Class.forName("io.sentry.snapshots.runtime.SentrySnapshot") as Class<out Annotation>
val ann = method.getAnnotation(annClass) ?: return@runCatching null
annClass.getDeclaredMethod("diffThreshold").invoke(ann) as? Float
}.getOrNull()
if (diffThreshold != null && diffThreshold != 0f) metadata["diff_threshold"] = diffThreshold

val json = metadata.entries.joinToString(",\n ", prefix = "{\n ", postfix = "\n}") { (k, v) ->
if (v is String) "\"" + k + "\": \"" + escapeJson(v) + "\""
else "\"" + k + "\": " + v
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20 changes: 20 additions & 0 deletions ...-build/src/test/kotlin/io/sentry/android/gradle/snapshot/GenerateSnapshotTestsTaskTest.kt
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Expand Up @@ -126,6 +126,26 @@ class GenerateSnapshotTestsTaskTest {
)
}

@Test
fun `generated sidecar reads SentrySnapshot annotation via reflection`() {
val content = generateAndRead(packageTrees = listOf("com.example"))

assertTrue(content.contains("Class.forName(preview.declaringClass)"))
assertTrue(content.contains("\"io.sentry.snapshots.runtime.SentrySnapshot\""))
assertTrue(content.contains("getDeclaredMethod(\"diffThreshold\")"))
}

@Test
fun `generated sidecar emits diff_threshold only when non-default`() {
val content = generateAndRead(packageTrees = listOf("com.example"))

assertTrue(
content.contains(
"if (diffThreshold != null && diffThreshold != 0f) metadata[\"diff_threshold\"] = diffThreshold"
)
)
}

@Test
fun `parseMajorVersion extracts major from standard semver`() {
assertEquals(1, parseMajorVersion("1.3.5"))
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