Gracefully handle compose errors and record compose preview information for displaying

snapshots/snapshots/src/main/kotlin/com/emergetools/snapshots/EmergeSnapshots.kt

@@ -58,4 +58,16 @@ class EmergeSnapshots : TestRule {
       composePreviewSnapshotConfig = composePreviewSnapshotConfig,
     )
   }
+
+  internal fun saveError(
+    type: SnapshotType,
+    composePreviewSnapshotConfig: ComposePreviewSnapshotConfig? = null,
+  ) {
+    SnapshotSaver.saveError(
+      displayName = null,
+      fqn = fqn,
+      type = type,
+      composePreviewSnapshotConfig = composePreviewSnapshotConfig,
+    )
+  }
 }

snapshots/snapshots/src/main/kotlin/com/emergetools/snapshots/SnapshotImageMetadata.kt

@@ -1,27 +1,51 @@
 package com.emergetools.snapshots
 
 import com.emergetools.snapshots.shared.ComposePreviewSnapshotConfig
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.JsonClassDiscriminator
 
 enum class SnapshotType {
   COMPOSABLE,
   VIEW,
   ACTIVITY,
 }
 
+@OptIn(ExperimentalSerializationApi::class)
 @Serializable
-internal data class SnapshotImageMetadata(
-  // Used as the primary key
-  val name: String,
-  @Deprecated("Use name instead")
-  val keyName: String,
-  // User defined name, or set to defaults by our backend
-  val displayName: String?,
-  // Filename of the outputted image
-  val filename: String,
-  // FQN of the test class
-  val fqn: String,
-  val type: SnapshotType,
-  // Compose-specific metadata, only set if type == COMPOSABLE
-  val composePreviewSnapshotConfig: ComposePreviewSnapshotConfig? = null,
-)
+@JsonClassDiscriminator("metadataType")
+sealed class SnapshotMetadata {
+  abstract val name: String
+  abstract val displayName: String?
+  abstract val fqn: String
+  abstract val type: SnapshotType
+  abstract val composePreviewSnapshotConfig: ComposePreviewSnapshotConfig?
+
+  @Serializable
+  internal class SuccessMetadata(
+    // Used as the primary key
+    override val name: String,
+    // User defined name, or set to defaults by our backend
+    override val displayName: String?,
+    // Filename of the outputted image
+    val filename: String,
+    // FQN of the test class
+    override val fqn: String,
+    override val type: SnapshotType,
+    // Compose-specific metadata, only set if type == COMPOSABLE
+    override val composePreviewSnapshotConfig: ComposePreviewSnapshotConfig? = null,
+  ) : SnapshotMetadata()
+
+  @Serializable
+  internal class ErrorMetadata(
+    // Used as the primary key
+    override val name: String,
+    // User defined name, or set to defaults by our backend
+    override val displayName: String?,
+    // FQN of the test class
+    override val fqn: String,
+    override val type: SnapshotType,
+    // Compose-specific metadata, only set if type == COMPOSABLE
+    override val composePreviewSnapshotConfig: ComposePreviewSnapshotConfig? = null,
+  ) : SnapshotMetadata()
+}

snapshots/snapshots/src/main/kotlin/com/emergetools/snapshots/SnapshotSaver.kt

@@ -31,6 +31,10 @@ internal object SnapshotSaver {
   private val args: Bundle
     get() = InstrumentationRegistry.getArguments()
 
+  private val saveMetadata: Boolean
+    get() = args.getBoolean(ARG_KEY_SAVE_METADATA, false) ||
+      args.getString(ARG_KEY_SAVE_METADATA, "false").toBoolean()
+
   fun save(
     displayName: String?,
     bitmap: Bitmap,
@@ -56,10 +60,7 @@ internal object SnapshotSaver {
       keyName = keyName,
       bitmap = bitmap
     )
-    if (
-      args.getBoolean(ARG_KEY_SAVE_METADATA, false) ||
-      args.getString(ARG_KEY_SAVE_METADATA, "false").toBoolean()
-    ) {
+    if (saveMetadata) {
       saveMetadata(
         snapshotsDir = snapshotsDir,
         displayName = displayName,
@@ -71,6 +72,37 @@ internal object SnapshotSaver {
     }
   }
 
+  fun saveError(
+    displayName: String?,
+    fqn: String,
+    type: SnapshotType,
+    composePreviewSnapshotConfig: ComposePreviewSnapshotConfig? = null,
+  ) {
+    val snapshotsDir = File(filesDir, SNAPSHOTS_DIR_NAME)
+    if (!snapshotsDir.exists() && !snapshotsDir.mkdirs()) {
+      error("Unable to create snapshots storage directory.")
+    }
+
+    // We need a stable key to use for the filename and comparison
+    // For composables, see [ComposePreviewSnapshotConfig.keyName]
+    // For non-composables, we use the normalized displayName
+    val keyName = keyName(
+      type = type,
+      displayName = displayName,
+      composePreviewSnapshotConfig = composePreviewSnapshotConfig,
+    )
+    if (saveMetadata) {
+      saveErrorMetadata(
+        snapshotsDir = snapshotsDir,
+        displayName = displayName,
+        keyName = keyName,
+        type = type,
+        fqn = fqn,
+        composePreviewSnapshotConfig = composePreviewSnapshotConfig,
+      )
+    }
+  }
+
   private fun saveImage(
     snapshotsDir: File,
     keyName: String,
@@ -89,17 +121,40 @@ internal object SnapshotSaver {
     type: SnapshotType,
     composePreviewSnapshotConfig: ComposePreviewSnapshotConfig? = null,
   ) {
-    val metadata = SnapshotImageMetadata(
+    val metadata: SnapshotMetadata = SnapshotMetadata.SuccessMetadata(
       name = keyName,
-      // TODO: Ryan remove in future
-      keyName = keyName,
       displayName = displayName,
       filename = "$keyName$PNG_EXTENSION",
       fqn = fqn,
       type = type,
       composePreviewSnapshotConfig = composePreviewSnapshotConfig,
     )
 
+    Log.d(TAG, "Saving error metadata for $keyName")
+    val jsonString = Json.encodeToString(metadata)
+
+    saveFile(snapshotsDir, "$keyName$JSON_EXTENSION") {
+      write(jsonString.toByteArray(Charset.defaultCharset()))
+    }
+  }
+
+  private fun saveErrorMetadata(
+    snapshotsDir: File,
+    keyName: String,
+    displayName: String?,
+    fqn: String,
+    type: SnapshotType,
+    composePreviewSnapshotConfig: ComposePreviewSnapshotConfig? = null,
+  ) {
+    val metadata: SnapshotMetadata = SnapshotMetadata.ErrorMetadata(
+      name = keyName,
+      displayName = displayName,
+      fqn = fqn,
+      type = type,
+      composePreviewSnapshotConfig = composePreviewSnapshotConfig,
+    )
+
+    Log.d(TAG, "Saving error metadata for $keyName")
     val jsonString = Json.encodeToString(metadata)
 
     saveFile(snapshotsDir, "$keyName$JSON_EXTENSION") {

snapshots/snapshots/src/main/kotlin/com/emergetools/snapshots/compose/EmergeComposeSnapshotReflectiveParameterizedInvoker.kt

@@ -6,6 +6,7 @@ import androidx.compose.ui.test.junit4.ComposeContentTestRule
 import androidx.compose.ui.test.junit4.createComposeRule
 import androidx.test.platform.app.InstrumentationRegistry
 import com.emergetools.snapshots.EmergeSnapshots
+import com.emergetools.snapshots.SnapshotType.COMPOSABLE
 import com.emergetools.snapshots.shared.ComposePreviewSnapshotConfig
 import com.emergetools.snapshots.shared.ComposeSnapshots
 import kotlinx.serialization.json.Json
@@ -51,25 +52,30 @@ class EmergeComposeSnapshotReflectiveParameterizedInvoker(private val previewCon
   val snapshotRule: EmergeSnapshots = EmergeSnapshots()
 
   @Test
+  @Suppress("TooGenericExceptionCaught")
   fun reflectiveComposableInvoker() {
-    composeRule.setContent {
-      val klass = Class.forName(previewConfig.fullyQualifiedClassName)
-      val composableMethod = klass.methods.find {
-        it.name == previewConfig.originalFqn.substringAfterLast(".")
-      }
+    try {
+      composeRule.setContent {
+        val klass = Class.forName(previewConfig.fullyQualifiedClassName)
+        val composableMethod = klass.methods.find {
+          it.name == previewConfig.originalFqn.substringAfterLast(".")
+        }
 
-      Log.d(TAG, "Invoking composable method: $composableMethod")
+        Log.d(TAG, "Invoking composable method: $composableMethod")
 
-      composableMethod?.let {
-        it.isAccessible = true
-        SnapshotVariantProvider(previewConfig) {
-          it.invoke(null, currentComposer, 0)
-        }
-      } ?: run {
-        // TODO: Ryan look to write error to file for better debugging
-        error("Unable to find composable method: ${previewConfig.originalFqn}")
+        composableMethod?.let {
+          it.isAccessible = true
+          SnapshotVariantProvider(previewConfig) {
+            it.invoke(null, currentComposer, 0)
+          }
+        } ?: error("Unable to find composable method: ${previewConfig.originalFqn}")
       }
+      snapshotRule.take(composeRule, previewConfig)
+    } catch (e: Exception) {
+      Log.e(TAG, "Error invoking composable method", e)
+      snapshotRule.saveError(COMPOSABLE, previewConfig)
+      // Re-throw to fail the test
+      throw e
     }
-    snapshotRule.take(composeRule, previewConfig)
   }
 }