Merge branch 'release-v0.22.x'

* release-v0.22.x:
  Finish release v0.22.4
  Releasing v0.22.4.
  0.22.4 CHANGELOG.md
  Flag out WorkflowTesting APIs when in Release mode
  Allow empty snapshots to be passed into launchWorkflowIn.

Author: dhavalshreyas

CHANGELOG.md

@@ -1,5 +1,16 @@
 Change Log
 ==========
+## Version 0.22.4
+
+_2020-01-15_
+
+### Kotlin
+
+ * Allow empty snapshots to be passed into launchWorkflowIn (#881)
+
+### Swift
+
+ * Flag out WorkflowTesting APIs when in Release mode  (#872)
 
 ## Version 0.22.3
 
@@ -508,7 +519,7 @@ _2019-3-12_
    method. (#57)
  * `BackStackEffect` allows configuration of transition effects between `BackStackScreen`s.
  * `ModalContainer` adds support for `AlertDialog` and custom views in `Dialog` windows.
- * Sample app consolidated to two modules, `samples/tictactoe/android` and 
+ * Sample app consolidated to two modules, `samples/tictactoe/android` and
    `samples/tictactoe/common`. Various `Shell*` classes in sample renamed to `Main*`.
  * Breaking change, `EventHandlingScreen` interface eliminated. It wasn't useful.
  * Breaking change, `workflow-core`, `workflow-rx2`, and `workflow-test` modules moved to legacy
@@ -528,7 +539,7 @@ _2019-1-4_
 
  * Breaking change, further API refinement of `WorkflowPool` and friends.
    Extracts `WorkflowUpdate` and `WorkflowPool.Handle` from the defunct
-   `WorkflowHandle`. (#114) 
+   `WorkflowHandle`. (#114)
 
 ## Version 0.6.0
 

Workflow.podspec

@@ -17,7 +17,7 @@ Pod::Spec.new do |s|
   s.source_files = 'swift/Workflow/Sources/*.swift'
 
   s.dependency 'ReactiveSwift', '~> 6.0.0'
- 
+
   s.test_spec 'Tests' do |test_spec|
     test_spec.source_files = 'swift/Workflow/Tests/**/*.swift'
     test_spec.framework = 'XCTest'

WorkflowUI.podspec

@@ -17,7 +17,7 @@ Pod::Spec.new do |s|
   s.source_files = 'swift/WorkflowUI/Sources/**/*.swift'
 
   s.dependency 'Workflow', "#{s.version}"
- 
+
   s.test_spec 'Tests' do |test_spec|
     test_spec.source_files = 'swift/WorkflowUI/Tests/**/*.swift'
     test_spec.framework = 'XCTest'

kotlin/workflow-runtime/src/main/java/com/squareup/workflow/LaunchWorkflow.kt

@@ -85,7 +85,7 @@ internal typealias Configurator <O, R, T> = CoroutineScope.(
  * will fail (report an exception up through [scope]). If this flow completes _after_ emitting at
  * least one value, the runtime will _not_ fail or stop, it will continue running with the
  * last-emitted input.
- * @param initialSnapshot If not null, used to restore the workflow.
+ * @param initialSnapshot If not null or empty, used to restore the workflow.
  * @param beforeStart Called exactly once with the flows for renderings/snapshots and outputs.
  * It also gets a sub-scope of [scope] with a newly created child [Job] which defines the lifetime
  * of the launched workflow tree. Cancelling that job ends the new workflow session.

kotlin/workflow-runtime/src/main/java/com/squareup/workflow/internal/WorkflowLoop.kt

@@ -35,8 +35,8 @@ internal interface WorkflowLoop {
    * Loops forever, or until the coroutine is cancelled, processing the workflow tree and emitting
    * updates by calling [onRendering] and [onOutput].
    *
-   * This function is the lowest-level entry point into the runtime. Don't call this directly, instead
-   * call [com.squareup.workflow.launchWorkflowIn].
+   * This function is the lowest-level entry point into the runtime. Don't call this directly,
+   * instead call [com.squareup.workflow.launchWorkflowIn].
    */
   @Suppress("LongParameterList")
   suspend fun <PropsT, StateT, OutputT : Any, RenderingT> runWorkflowLoop(
@@ -76,7 +76,7 @@ internal open class RealWorkflowLoop : WorkflowLoop {
           id = workflow.id(),
           workflow = workflow,
           initialProps = input,
-          snapshot = initialSnapshot?.bytes,
+          snapshot = initialSnapshot?.bytes?.takeUnless { it.size == 0 },
           baseContext = coroutineContext,
           parentDiagnosticId = null,
           diagnosticListener = diagnosticListener,

kotlin/workflow-testing/src/test/java/com/squareup/workflow/SnapshottingIntegrationTest.kt

@@ -49,6 +49,18 @@ class SnapshottingIntegrationTest {
     }
   }
 
+  @Test fun `empty snapshot is ignored`() {
+    val root = TreeWorkflow("root")
+    val snapshot = Snapshot.EMPTY
+
+    root.testFromStart(
+        props = "initial props",
+        testParams = WorkflowTestParams(startFrom = StartFromCompleteSnapshot(snapshot))
+    ) {
+      // Success!
+    }
+  }
+
   @Test fun `snapshots and restores parent child workflows`() {
     val root = TreeWorkflow("root", TreeWorkflow("leaf"))
     var snapshot: Snapshot? = null