Short circuit rememberRetained if the LocalRetainedStateRegistry …

…isn't set (#1438)

Fixes #1434

CHANGELOG.md

@@ -4,6 +4,8 @@ Changelog
 **Unreleased**
 --------------
 
+- **Fix**: Fix `rememberRetained` implicitly requiring `LocalContext` where it used to no-op.
+
 0.22.0
 ------
 

circuit-retained/src/androidInstrumentedTest/kotlin/com/slack/circuit/retained/android/RetainedSaveableTest.kt

@@ -24,6 +24,7 @@ import com.slack.circuit.retained.Continuity
 import com.slack.circuit.retained.ContinuityViewModel
 import com.slack.circuit.retained.LocalCanRetainChecker
 import com.slack.circuit.retained.LocalRetainedStateRegistry
+import com.slack.circuit.retained.NoOpRetainedStateRegistry
 import com.slack.circuit.retained.continuityRetainedStateRegistry
 import com.slack.circuit.retained.rememberCanRetainChecker
 import com.slack.circuit.retained.rememberRetained
@@ -125,6 +126,44 @@ class RetainedSaveableTest {
     composeTestRule.onNodeWithTag("superBigData").assertTextEquals("null")
   }
 
+  @Test
+  fun saveableIsUsedWhenRetainIsNoop() {
+    var id = 0
+    lateinit var data: CacheableData
+
+    fun setContent() {
+      scenario.onActivity { activity ->
+        activity.setContent {
+          CompositionLocalProvider(LocalRetainedStateRegistry provides NoOpRetainedStateRegistry) {
+            data = rememberRetained(saver = CacheableData.Saver) { CacheableData(id++) }
+            Text(modifier = Modifier.testTag("id"), text = "${data.id}")
+            Text(modifier = Modifier.testTag("superBigData"), text = "${data.superBigData}")
+          }
+        }
+      }
+    }
+
+    setContent()
+
+    // Check initial state is correct
+    composeTestRule.onNodeWithTag("id").assertTextEquals("0")
+    composeTestRule.onNodeWithTag("superBigData").assertTextEquals("null")
+
+    data.superBigData = "Super big data"
+    composeTestRule.waitForIdle()
+
+    composeTestRule.onNodeWithTag("id").assertTextEquals("0")
+    composeTestRule.onNodeWithTag("superBigData").assertTextEquals("Super big data")
+
+    scenario.recreate()
+
+    setContent()
+
+    // Retained state is not preserved, but id is
+    composeTestRule.onNodeWithTag("id").assertTextEquals("0")
+    composeTestRule.onNodeWithTag("superBigData").assertTextEquals("null")
+  }
+
   private fun setActivityContent(content: @Composable () -> Unit) {
     scenario.onActivity { activity ->
       activity.setContent {

circuit-retained/src/commonMain/kotlin/com/slack/circuit/retained/RememberRetained.kt

@@ -17,6 +17,7 @@ import androidx.compose.runtime.saveable.SaveableStateRegistry
 import androidx.compose.runtime.saveable.Saver
 import androidx.compose.runtime.saveable.SaverScope
 import androidx.compose.runtime.saveable.autoSaver
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.snapshots.SnapshotMutableState
 import androidx.compose.runtime.structuralEqualityPolicy
 
@@ -144,7 +145,10 @@ public fun <T : Any> rememberRetained(
 ): T {
   val saveableStateRegistry = LocalSaveableStateRegistry.current
   val retainedStateRegistry = LocalRetainedStateRegistry.current
-
+  // Short-circuit no-ops
+  if (retainedStateRegistry === NoOpRetainedStateRegistry) {
+    return rememberSaveable(inputs = inputs, saver = saver, init = init)
+  }
   val compositeKey = currentCompositeKeyHash
   // key is the one provided by the user or the one generated by the compose runtime
   val finalKey =