Add expectCovariantWorkflow for expecting via workflow classes that have generics

workflow-core/src/jvmMain/kotlin/com/squareup/workflow1/WorkflowIdentifierEx.kt

@@ -10,7 +10,6 @@ import kotlin.reflect.KClass
  * This workflow must not be an [ImpostorWorkflow], or this property will throw an
  * [IllegalArgumentException].
  */
-@OptIn(ExperimentalStdlibApi::class)
 @get:TestOnly
 public val KClass<out Workflow<*, *, *>>.workflowIdentifier: WorkflowIdentifier
   get() {

workflow-testing/api/workflow-testing.api

@@ -25,6 +25,8 @@ public abstract interface class com/squareup/workflow1/testing/RenderTestResult
 }
 
 public abstract class com/squareup/workflow1/testing/RenderTester {
+	public static final field Companion Lcom/squareup/workflow1/testing/RenderTester$Companion;
+	public static final field VERIFY_ALL_LEVELS I
 	public fun <init> ()V
 	public abstract fun expectRemember (Ljava/lang/String;ZLkotlin/jvm/functions/Function1;)Lcom/squareup/workflow1/testing/RenderTester;
 	public static synthetic fun expectRemember$default (Lcom/squareup/workflow1/testing/RenderTester;Ljava/lang/String;ZLkotlin/jvm/functions/Function1;ILjava/lang/Object;)Lcom/squareup/workflow1/testing/RenderTester;
@@ -51,6 +53,9 @@ public final class com/squareup/workflow1/testing/RenderTester$ChildWorkflowMatc
 	public static final field INSTANCE Lcom/squareup/workflow1/testing/RenderTester$ChildWorkflowMatch$NotMatched;
 }
 
+public final class com/squareup/workflow1/testing/RenderTester$Companion {
+}
+
 public final class com/squareup/workflow1/testing/RenderTester$RememberInvocation {
 	public fun <init> (Ljava/lang/String;Lkotlin/reflect/KType;Ljava/util/List;)V
 	public final fun getInputs ()Ljava/util/List;
@@ -68,6 +73,8 @@ public final class com/squareup/workflow1/testing/RenderTester$RenderChildInvoca
 }
 
 public final class com/squareup/workflow1/testing/RenderTesterKt {
+	public static final fun expectCovariantWorkflow (Lcom/squareup/workflow1/testing/RenderTester;Lkotlin/reflect/KClass;Lkotlin/reflect/KType;ILkotlin/reflect/KType;ILjava/lang/Object;Lcom/squareup/workflow1/WorkflowOutput;Ljava/lang/String;Ljava/lang/String;Lkotlin/jvm/functions/Function1;)Lcom/squareup/workflow1/testing/RenderTester;
+	public static synthetic fun expectCovariantWorkflow$default (Lcom/squareup/workflow1/testing/RenderTester;Lkotlin/reflect/KClass;Lkotlin/reflect/KType;ILkotlin/reflect/KType;ILjava/lang/Object;Lcom/squareup/workflow1/WorkflowOutput;Ljava/lang/String;Ljava/lang/String;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)Lcom/squareup/workflow1/testing/RenderTester;
 	public static final fun expectRemember (Lcom/squareup/workflow1/testing/RenderTester;Ljava/lang/String;Lkotlin/reflect/KType;[Ljava/lang/Object;Ljava/lang/String;Lkotlin/jvm/functions/Function1;)Lcom/squareup/workflow1/testing/RenderTester;
 	public static synthetic fun expectRemember$default (Lcom/squareup/workflow1/testing/RenderTester;Ljava/lang/String;Lkotlin/reflect/KType;[Ljava/lang/Object;Ljava/lang/String;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)Lcom/squareup/workflow1/testing/RenderTester;
 	public static final fun expectSideEffect (Lcom/squareup/workflow1/testing/RenderTester;Ljava/lang/String;)Lcom/squareup/workflow1/testing/RenderTester;

workflow-testing/src/main/java/com/squareup/workflow1/testing/RealRenderTester.kt

@@ -460,14 +460,25 @@ internal fun createRenderChildInvocation(
  * Returns true iff this identifier's [WorkflowIdentifier.getRealIdentifierType] is the same type as
  * or a subtype of [expected]'s.
  */
-internal fun WorkflowIdentifier.realTypeMatchesExpectation(
+internal fun WorkflowIdentifier.realTypeMatchesClassExpectation(
   expected: WorkflowIdentifier
 ): Boolean {
   val expectedType = expected.realType
   val actualType = realType
   return actualType.matchesExpectation(expectedType)
 }
 
+/**
+ * Returns true iff this identifier's [WorkflowIdentifier.getRealIdentifierType]  has the same
+ * class (or is a subtype) of the [expectedKClass].
+ */
+internal fun WorkflowIdentifier.realTypeMatchesClassExpectation(
+  expectedKClass: KClass<*>
+): Boolean {
+  val actualType = realType
+  return actualType.matchesClassExpectation(expectedKClass)
+}
+
 internal fun WorkflowIdentifierType.matchesExpectation(expected: WorkflowIdentifierType): Boolean {
   return when {
     this is Snapshottable && expected is Snapshottable -> matchesSnapshottable(expected)
@@ -476,6 +487,18 @@ internal fun WorkflowIdentifierType.matchesExpectation(expected: WorkflowIdentif
   }
 }
 
+internal fun WorkflowIdentifierType.matchesClassExpectation(expectedKClass: KClass<*>): Boolean {
+  return when (this) {
+    is Snapshottable -> kClass?.let { actualKClass ->
+      expectedKClass.isSuperclassOf(actualKClass) || actualKClass.isJavaMockOf(expectedKClass)
+    } == true
+    is Unsnapshottable -> (kType.classifier as? KClass<*>)?.let { actualKClass ->
+      expectedKClass.isSuperclassOf(actualKClass) || actualKClass.isJavaMockOf(expectedKClass)
+    } == true
+    else -> false
+  }
+}
+
 private fun Snapshottable.matchesSnapshottable(expected: Snapshottable): Boolean =
   kClass?.let { actualKClass ->
     expected.kClass?.let { expectedKClass ->

workflow-testing/src/main/java/com/squareup/workflow1/testing/RenderTester.kt

@@ -14,6 +14,7 @@ import com.squareup.workflow1.WorkflowOutput
 import com.squareup.workflow1.config.JvmTestRuntimeConfigTools
 import com.squareup.workflow1.identifier
 import com.squareup.workflow1.testing.RenderTester.ChildWorkflowMatch
+import com.squareup.workflow1.testing.RenderTester.Companion
 import com.squareup.workflow1.workflowIdentifier
 import kotlinx.coroutines.CoroutineScope
 import kotlin.reflect.KClass
@@ -378,6 +379,10 @@ public abstract class RenderTester<PropsT, StateT, OutputT, RenderingT> {
       public val output: WorkflowOutput<*>? = null
     ) : ChildWorkflowMatch()
   }
+
+  public companion object {
+    public const val VERIFY_ALL_LEVELS: Int = -1
+  }
 }
 
 /**
@@ -389,6 +394,13 @@ public abstract class RenderTester<PropsT, StateT, OutputT, RenderingT> {
  * concrete class, your render tests can pass the class of the interface to this method instead of
  * the actual class that implements it.
  *
+ * Note that Workflow<Int, String, Int> is *not* a sub-type of Workflow<Int, Object, Int> because
+ * it is not covariant for the [OutputT] generic (the same is true for [PropsT]). This means that
+ * you cannot use the [WorkflowIdentifier] or [KClass] of a Workflow class whose [OutputT] or
+ * [PropsT] are supertypes to the one you want to match. If this is the only reasonable class
+ * definition you have access to, then consider using [expectCovariantWorkflow] and specifying
+ * those types explicitly.
+ *
  * ## Expecting impostor workflows
  *
  * If the workflow-under-test renders an
@@ -448,6 +460,13 @@ public inline fun <ChildRenderingT, PropsT, StateT, OutputT, RenderingT>
  * concrete class, your render tests can pass the class of the interface to this method instead of
  * the actual class that implements it.
  *
+ * Note that Workflow<Int, String, Int> is *not* a sub-type of Workflow<Int, Object, Int> because
+ * it is not covariant for the [OutputT] generic (the same is true for [PropsT]). This means that
+ * you cannot use the [WorkflowIdentifier] or [KClass] of a Workflow class whose [OutputT] or
+ * [PropsT] are supertypes to the one you want to match. If this is the only reasonable class
+ * definition you have access to, then consider using [expectCovariantWorkflow] and specifying
+ * those types explicitly.
+ *
  * ## Expecting impostor workflows
  *
  * If the workflow-under-test renders an
@@ -509,7 +528,7 @@ public fun <ChildOutputT, ChildRenderingT, PropsT, StateT, OutputT, RenderingT>
       "output=$output"
   }
 ) { invocation ->
-  if (invocation.workflow.identifier.realTypeMatchesExpectation(identifier) &&
+  if (invocation.workflow.identifier.realTypeMatchesClassExpectation(identifier) &&
     invocation.renderKey == key
   ) {
     assertProps(invocation.props)
@@ -528,6 +547,13 @@ public fun <ChildOutputT, ChildRenderingT, PropsT, StateT, OutputT, RenderingT>
  * concrete class, your render tests can pass the class of the interface to this method instead of
  * the actual class that implements it.
  *
+ * Note that Workflow<Int, String, Int> is *not* a sub-type of Workflow<Int, Object, Int> because
+ * it is not covariant for the [OutputT] generic (the same is true for [PropsT]). This means that
+ * you cannot use the [WorkflowIdentifier] or [KClass] of a Workflow class whose [OutputT] or
+ * [PropsT] are supertypes to the one you want to match. If this is the only reasonable class
+ * definition you have access to, then consider using [expectCovariantWorkflow] and specifying
+ * those types explicitly.
+ *
  * ## Expecting impostor workflows
  *
  * If the workflow-under-test renders an
@@ -549,7 +575,8 @@ public fun <ChildOutputT, ChildRenderingT, PropsT, StateT, OutputT, RenderingT>
  *
  * @param workflowType The [KClass] of the expected workflow. May also be any of the supertypes
  * of the expected workflow, e.g. if the workflow type is an interface and the workflow-under-test
- * injects a fake.
+ * injects a fake. See note above about covariance with [PropsT] and [OutputT] and how these cannot
+ * help with supertypes.
  *
  * @param rendering The rendering to return from
  * [renderChild][com.squareup.workflow1.BaseRenderContext.renderChild] when this workflow is
@@ -589,6 +616,143 @@ public inline fun <ChildPropsT, ChildOutputT, ChildRenderingT, PropsT, StateT, O
     }
   )
 
+/**
+ * @see [expectWorkflow] for more on this expectation.
+ *
+ * This is a special use version for when the only reasonable [KClass] you have to verify against
+ * is the definition of a workflow whose [OutputT] and [RenderingT] are supertypes of the [OutputT]
+ * and [RenderingT] of the child workflow type you expect to be rendered.
+ * In other words, the expected workflow is covariant with the class you have to pass to the
+ * expectation. (There is a slight nuance here, in that if the [OutputT] is a supertype of the
+ * expected child's [OutputT], then those workflow's are not actually covariant since [OutputT]
+ * is an invariant generic type. This is not important for the use of this expectation, however.)
+ *
+ * The most common need for this is when you are using a generic factory to construct Workflow
+ * instances that you then wish to expect in your test.
+ *
+ * In that case, use this expectation and provide the [KClass] of the Workflow type, along with the
+ * [KType] of the [OutputT] and [RenderingT]. The [PropsT] can simply be verified for type safety
+ * inside [assertProps] by casting the [Any?] into the expected [PropsT].
+ *
+ * Note that this implementation does not handle [ImpostorWorkflow][com.squareup.workflow1.ImpostorWorkflow]s
+ * (for proxied identifiers) like the other versions do.
+ *
+ * @param childWorkflowClass The [KClass] of the expected workflow or one of its supertypes,
+ * including covariant supertypes. E.g. if the workflow type is an interface and the
+ * workflow-under-test injects a fake.
+ *
+ * @param childOutputType The [KType] of the [OutputT] of the expected child workflow.
+ *
+ * @param outputTypeVerificationLevel The number of 'levels' of generic arguments to verify in
+ * the [OutputT], e.g., for `Wrapper<*>` and level 1 only `Wrapper` would be checked, whereas for
+ * level 2, `Wrapper` and `*` (the star projection) would be checked against the
+ * [RenderChildInvocation].
+ *
+ * @param childRenderingType The [KType] of the [RenderingT] of the expected child workflow.
+ *
+ * @param renderingTypeVerificationLevel The number of 'levels' of generic arguments to verify in
+ * the [OutputT], e.g., for `Wrapper<*>` and level 1 only `Wrapper` would be checked, whereas for
+ * level 2, `Wrapper` and `*` (the star projection) would be checked against the
+ * [RenderChildInvocation].
+ *
+ * @param rendering The rendering to return from
+ * [renderChild][com.squareup.workflow1.BaseRenderContext.renderChild] when this workflow is
+ * rendered.
+ *
+ * @param key The key passed to [renderChild][com.squareup.workflow1.BaseRenderContext.renderChild]
+ * when rendering this workflow.
+ *
+ * @param assertProps A function that performs assertions on the props passed to
+ * [renderChild][com.squareup.workflow1.BaseRenderContext.renderChild].
+ *
+ * @param output If non-null, [WorkflowOutput.value] will be "emitted" when this workflow is
+ * rendered. The [WorkflowAction] used to handle this output can be verified using methods on
+ * [RenderTestResult].
+ *
+ * @param description Optional string that will be used to describe this expectation in error
+ * messages.
+ */
+public fun <ChildOutputT, ChildRenderingT, PropsT, StateT, OutputT, RenderingT>
+  RenderTester<PropsT, StateT, OutputT, RenderingT>.expectCovariantWorkflow(
+  childWorkflowClass: KClass<*>,
+  childOutputType: KType,
+  outputTypeVerificationLevel: Int = RenderTester.VERIFY_ALL_LEVELS,
+  childRenderingType: KType,
+  renderingTypeVerificationLevel: Int = Companion.VERIFY_ALL_LEVELS,
+  rendering: ChildRenderingT,
+  output: WorkflowOutput<ChildOutputT>? = null,
+  key: String = "",
+  description: String = "",
+  assertProps: (props: Any?) -> Unit = {}
+): RenderTester<PropsT, StateT, OutputT, RenderingT> = expectWorkflow(
+  exactMatch = true,
+  description = description.ifBlank {
+    "workflow " +
+      "workflowClass=$childWorkflowClass, " +
+      "childOutputType=$childOutputType, " +
+      "childRenderingType=$childRenderingType, " +
+      "key=$key, " +
+      "rendering=$rendering, " +
+      "output=$output"
+  }
+) { invocation ->
+  // Recursive function to verify #n levels of types.
+  fun verifyTypesToLevel(
+    levels: Int,
+    type1: KType,
+    type2: KType
+  ): Boolean {
+    if (levels < 1) return true
+    if (levels == 1) {
+      // We are at the last level of verification, ignore any further generic type arguments.
+      return type1.classifier?.equals(type2.classifier) == true
+    } else {
+      if (type1.arguments.size != type2.arguments.size) return false
+      var acc = true
+      type1.arguments.forEachIndexed { index, kTypeProjection1 ->
+        val kTypeProjection2 = type2.arguments[index]
+        if (kTypeProjection1.type == null || kTypeProjection2.type == null) return false
+        acc =
+          acc && verifyTypesToLevel(levels - 1, kTypeProjection1.type!!, kTypeProjection2.type!!)
+      }
+      return acc
+    }
+  }
+
+  val childClassTypeMatches =
+    invocation.workflow.identifier.realTypeMatchesClassExpectation(childWorkflowClass)
+  val keyMatches = invocation.renderKey == key
+  val outputTypeMatches = invocation.outputType.type?.equals(childOutputType) == true ||
+    (
+      (outputTypeVerificationLevel > 0 && invocation.outputType.type != null) &&
+        verifyTypesToLevel(
+          outputTypeVerificationLevel,
+          invocation.outputType.type!!,
+          childOutputType
+        )
+      )
+  val renderingTypeMatchers = invocation.renderingType.type?.equals(childRenderingType) == true ||
+    (
+      (renderingTypeVerificationLevel > 0 && invocation.renderingType.type != null) &&
+        verifyTypesToLevel(
+          renderingTypeVerificationLevel,
+          invocation.renderingType.type!!,
+          childRenderingType
+        )
+      )
+
+  if (childClassTypeMatches &&
+    keyMatches &&
+    outputTypeMatches &&
+    renderingTypeMatchers
+  ) {
+    assertProps(invocation.props)
+    ChildWorkflowMatch.Matched(rendering, output)
+  } else {
+    ChildWorkflowMatch.NotMatched
+  }
+}
+
 /**
  * Specifies that this render pass is expected to run a particular side effect.
  *