document passing in bad track frame format is an error

Author: davidliu

livekit-android-sdk/src/main/java/io/livekit/android/room/datatrack/DataTrackPublishOptions.kt

@@ -42,6 +42,9 @@ data class DataTrackPublishOptions(
  * A schema always describes frames in a specific encoding, so [frameEncoding] is required
  * alongside a [schema]. The declared metadata is surfaced to subscribers via [DataTrackInfo].
  *
+ * Whether a schema's encoding can actually describe frames in [frameEncoding] is checked when the
+ * track is published, surfacing as [DataTrackPublishException.InvalidSchema].
+ *
  * @param frameEncoding Encoding of the track's frames.
  * @param schema Schema describing the track's frames.
  */

livekit-android-test/src/main/java/io/livekit/android/test/mock/room/datatrack/MockLocalDataTrackManager.kt

@@ -27,6 +27,7 @@ import io.livekit.uniffi.NoHandle
 import livekit.LivekitModels
 import livekit.LivekitRtc
 import uniffi.livekit_datatrack.EncryptionProvider
+import uniffi.livekit_datatrack.PublishException
 
 class MockLocalDataTrackManagerFactory : LocalDataTrackManagerFactory {
     /**
@@ -46,13 +47,22 @@ class MockLocalDataTrackManagerFactory : LocalDataTrackManagerFactory {
      */
     var createError: LinkageError? = null
 
+    /**
+     * When set, every manager this creates fails [MockLocalDataTrackManager.publishTrack] with it,
+     * standing in for a publish the native core rejects.
+     */
+    var publishError: PublishException? = null
+
     override fun create(
         delegate: LocalDataTrackManagerDelegate,
         encryptionProvider: EncryptionProvider?,
     ): LocalDataTrackManagerInterface {
         createError?.let { throw it }
         lastEncryptionProvider = encryptionProvider
-        return MockLocalDataTrackManager(delegate).also { manager = it }
+        return MockLocalDataTrackManager(delegate).also {
+            it.publishError = publishError
+            manager = it
+        }
     }
 }
 
@@ -87,7 +97,11 @@ class MockLocalDataTrackManager(
         }
     }
 
+    /** Set to make [publishTrack] fail the way the native manager does. */
+    var publishError: PublishException? = null
+
     override suspend fun publishTrack(options: DataTrackOptions): LocalDataTrack {
+        publishError?.let { throw it }
         val request = LivekitRtc.SignalRequest.newBuilder()
             .setPublishDataTrackRequest(
                 LivekitRtc.PublishDataTrackRequest.newBuilder()

livekit-android-test/src/test/java/io/livekit/android/room/datatrack/OutgoingDataTrackManagerMockE2ETest.kt

@@ -40,6 +40,7 @@ import org.junit.Assert.assertNotSame
 import org.junit.Assert.assertNull
 import org.junit.Assert.assertTrue
 import org.junit.Test
+import uniffi.livekit_datatrack.PublishException
 
 @OptIn(ExperimentalCoroutinesApi::class)
 class OutgoingDataTrackManagerMockE2ETest : MockE2ETest() {
@@ -68,6 +69,29 @@ class OutgoingDataTrackManagerMockE2ETest : MockE2ETest() {
         assertTrue(result.exceptionOrNull() is DataTrackPublishException.Internal)
     }
 
+    /**
+     * The core rejects a schema whose encoding cannot describe the track's frames (and the other
+     * schema-metadata rules) before it allocates a handle. This covers the SDK's half: that the
+     * refusal reaches the caller as a typed failure rather than an opaque one.
+     */
+    @Test
+    fun publishDataTrackSurfacesInvalidSchemaFromTheCore() = runTest {
+        localDataTrackManagerFactory.publishError =
+            PublishException.InvalidSchema("Specified schema and frame encodings are incompatible")
+        connect()
+
+        val result = room.localParticipant.publishDataTrack(
+            "telemetry",
+            DataTrackPublishOptions(
+                DataTrackFrameEncoding.Cdr,
+                DataTrackSchemaId("reading.v1", DataTrackSchemaEncoding.JsonSchema),
+            ),
+        )
+
+        assertTrue(result.isFailure)
+        assertTrue(result.exceptionOrNull() is DataTrackPublishException.InvalidSchema)
+    }
+
     @Test
     fun publishDataTrackPassesEncryptionProviderWhenE2eeEnabled() = runTest {
         room.e2eeOptions = E2EEOptions(keyProvider = NoopKeyProvider())