From 3137fe4005d9ad859cdb45b719b2170961e2ff2a Mon Sep 17 00:00:00 2001
From: Pat Garrity <pfm@garrity.co>
Date: Sat, 13 Sep 2025 10:21:48 -0500
Subject: [PATCH] Successfully run an engine with no tests.

---
 build.sbt                                     |  5 +-
 .../test/v0/reporting/InMemoryReporter.scala  | 25 ++---
 .../test/v0/runtime/engine/TestEngine.scala   | 28 +++---
 .../v0/runtime/engine/TestEngineTests.scala   | 81 ++++++++++++++++
 .../src/test/scala/support/Generators.scala   | 20 +++-
 .../test/scala/support/TestEntryPoint.scala   | 48 ++++++++++
 .../src/test/scala/support/TestSpan.scala     | 93 +++++++++++++++++++
 7 files changed, 266 insertions(+), 34 deletions(-)
 create mode 100644 modules/runtime/src/test/scala/gs/test/v0/runtime/engine/TestEngineTests.scala
 create mode 100644 modules/test-support/src/test/scala/support/TestEntryPoint.scala
 create mode 100644 modules/test-support/src/test/scala/support/TestSpan.scala

diff --git a/build.sbt b/build.sbt
index a965705..34e3c3a 100644
--- a/build.sbt
+++ b/build.sbt
@@ -41,7 +41,7 @@ val Deps = new {
   val Gs = new {
     val Uuid: ModuleID    = "gs" %% "gs-uuid-v0"         % "0.4.1"
     val Timing: ModuleID  = "gs" %% "gs-timing-v0"       % "0.1.2"
-    val Datagen: ModuleID = "gs" %% "gs-datagen-core-v0" % "0.3.1"
+    val Datagen: ModuleID = "gs" %% "gs-datagen-core-v0" % "0.3.3"
   }
 
   val MUnit: ModuleID = "org.scalameta" %% "munit" % "1.1.1"
@@ -78,7 +78,8 @@ lazy val `test-support` = project
   .settings(
     libraryDependencies ++= Seq(
       Deps.Cats.Core,
-      Deps.Cats.Effect
+      Deps.Cats.Effect,
+      Deps.Natchez.Core
     )
   )
 
diff --git a/modules/reporting/src/main/scala/gs/test/v0/reporting/InMemoryReporter.scala b/modules/reporting/src/main/scala/gs/test/v0/reporting/InMemoryReporter.scala
index eb31865..08bde16 100644
--- a/modules/reporting/src/main/scala/gs/test/v0/reporting/InMemoryReporter.scala
+++ b/modules/reporting/src/main/scala/gs/test/v0/reporting/InMemoryReporter.scala
@@ -2,6 +2,7 @@ package gs.test.v0.reporting
 
 import cats.effect.Async
 import cats.effect.Ref
+import cats.effect.Resource
 import cats.effect.std.Queue
 import cats.syntax.all.*
 import gs.test.v0.api.GroupResult
@@ -10,7 +11,7 @@ import gs.test.v0.api.TestExecution
 
 final class InMemoryReporter[F[_]: Async] private (
   suiteExecution: Ref[F, Option[SuiteExecution]],
-  groupResults: Queue[F, (GroupResult, List[TestExecution])]
+  groupResults: Queue[F, Option[(GroupResult, List[TestExecution])]]
 ) extends Reporter[F]:
 
   /** @inheritDocs
@@ -22,7 +23,7 @@ final class InMemoryReporter[F[_]: Async] private (
   override def reportGroup(
     groupResult: GroupResult,
     testExecutions: List[TestExecution]
-  ): F[Unit] = groupResults.offer(groupResult -> testExecutions)
+  ): F[Unit] = groupResults.offer(Some(groupResult -> testExecutions))
 
   /** @inheritDocs
     */
@@ -31,20 +32,22 @@ final class InMemoryReporter[F[_]: Async] private (
 
   /** @inheritDocs
     */
-  override def endReport(): F[Unit] = Async[F].unit
+  override def endReport(): F[Unit] = groupResults.offer(None)
 
   def getSuiteExecution(): F[Option[SuiteExecution]] = suiteExecution.get
 
-  // TODO: make stream to consume and reify to list
-  def getGroupResults(): F[List[(GroupResult, List[TestExecution])]] =
-    ???
+  def terminateAndGetResults(): F[List[(GroupResult, List[TestExecution])]] =
+    endReport() *>
+      fs2.Stream.fromQueueNoneTerminated(groupResults).compile.toList
 
 object InMemoryReporter:
 
-  def initialize[F[_]: Async]: F[InMemoryReporter[F]] =
-    for
-      se <- Ref.of[F, Option[SuiteExecution]](None)
-      gr <- Queue.unbounded[F, (GroupResult, List[TestExecution])]
-    yield new InMemoryReporter(se, gr)
+  def provision[F[_]: Async]: Resource[F, InMemoryReporter[F]] =
+    Resource.make(
+      for
+        se <- Ref.of[F, Option[SuiteExecution]](None)
+        gr <- Queue.unbounded[F, Option[(GroupResult, List[TestExecution])]]
+      yield new InMemoryReporter(se, gr)
+    )(_ => Async[F].unit)
 
 end InMemoryReporter
diff --git a/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/TestEngine.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/TestEngine.scala
index b102235..9a68091 100644
--- a/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/TestEngine.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/TestEngine.scala
@@ -1,7 +1,6 @@
 package gs.test.v0.runtime.engine
 
 import cats.effect.Async
-import cats.effect.Resource
 import cats.syntax.all.*
 import gs.test.v0.api.GroupResult
 import gs.test.v0.api.SuiteExecution
@@ -51,8 +50,8 @@ import natchez.Span
   */
 final class TestEngine[F[_]: Async](
   val configuration: EngineConfiguration,
-  reporter: Reporter[F],
-  entryPoint: EntryPoint[F],
+  val reporter: Reporter[F],
+  val entryPoint: EntryPoint[F],
   timing: Timing[F]
 ):
 
@@ -310,32 +309,29 @@ final class TestEngine[F[_]: Async](
 
 object TestEngine:
 
-  /** Provision a new [[TestEngine]].
+  /** Initialize a new [[TestEngine]].
     *
     * @param configuration
     *   The [[EngineConfiguration]] used for this instance.
     * @param reporter
-    *   Resource which manages the [[Reporter]].
+    *   Reports test results.
     * @param entryPoint
-    *   Resource which manages the telemetry entry point.
+    *   Entry point for OpenTelemetry support.
     * @param timing
     *   Timing controller.
     * @return
     *   Resource which manages the [[TestEngine]].
     */
-  def provision[F[_]: Async](
+  def initialize[F[_]: Async](
     configuration: EngineConfiguration,
-    reporter: Resource[F, Reporter[F]],
-    entryPoint: Resource[F, EntryPoint[F]],
+    reporter: Reporter[F],
+    entryPoint: EntryPoint[F],
     timing: Timing[F]
-  ): Resource[F, TestEngine[F]] =
-    for
-      r  <- reporter
-      ep <- entryPoint
-    yield new TestEngine(
+  ): TestEngine[F] =
+    new TestEngine(
       configuration = configuration,
-      reporter = r,
-      entryPoint = ep,
+      reporter = reporter,
+      entryPoint = entryPoint,
       timing = timing
     )
 
diff --git a/modules/runtime/src/test/scala/gs/test/v0/runtime/engine/TestEngineTests.scala b/modules/runtime/src/test/scala/gs/test/v0/runtime/engine/TestEngineTests.scala
new file mode 100644
index 0000000..aaf7bd1
--- /dev/null
+++ b/modules/runtime/src/test/scala/gs/test/v0/runtime/engine/TestEngineTests.scala
@@ -0,0 +1,81 @@
+package gs.test.v0.runtime.engine
+
+import cats.effect.IO
+import cats.effect.Resource
+import gs.test.v0.api.TestGroupDefinition
+import gs.test.v0.reporting.InMemoryReporter
+import gs.test.v0.runtime.engine.TestEngineTests.EngineObservation
+import gs.timing.v0.MonotonicProvider.ManualTickProvider
+import gs.timing.v0.Timing
+import gs.uuid.v0.UUID
+import java.time.Clock
+import munit.*
+import support.*
+
+class TestEngineTests extends IOSuite:
+
+  import TestEngineTests.TestData
+
+  iotest("should run an engine with no tests") {
+    newEngine().use { obs =>
+      for
+        suiteExecution <- obs.engine.runSuite(
+          suite = Generators.testSuite(),
+          tests = emptyStream[TestGroupDefinition[IO]]
+        )
+        rootSpan <- obs.entryPoint.getSpan(EngineConstants.Tracing.RootSpan)
+        results  <- obs.reporter.terminateAndGetResults()
+      yield
+        assertEquals(rootSpan.isDefined, true)
+        assertEquals(results.isEmpty, true)
+        assertEquals(suiteExecution.seen, 0L)
+        assertEquals(suiteExecution.passed, 0L)
+        assertEquals(suiteExecution.failed, 0L)
+    }
+  }
+
+  private def emptyStream[A]: fs2.Stream[IO, A] =
+    fs2.Stream.empty
+
+  private def liftToResource[A](io: IO[A]): Resource[IO, A] =
+    Resource.make(io)(_ => IO.unit)
+
+  def newEngine(): Resource[IO, EngineObservation] =
+    for
+      (tickProvider, timing) <- liftToResource(Timing.manual[IO])
+      reporter               <- InMemoryReporter.provision[IO]
+      entryPoint             <- TestEntryPoint.provision()
+    yield EngineObservation(
+      tickProvider = tickProvider,
+      reporter = reporter,
+      entryPoint = entryPoint,
+      engine = TestEngine.initialize[IO](
+        configuration = TestData.Config,
+        reporter = reporter,
+        entryPoint = entryPoint,
+        timing = timing
+      )
+    )
+
+object TestEngineTests:
+
+  private object TestData:
+
+    val Config: EngineConfiguration = EngineConfiguration(
+      groupConcurrency = ConcurrencySetting.Serial,
+      testConcurrency = ConcurrencySetting.Serial,
+      clock = Clock.systemUTC(),
+      suiteIdGenerator = UUID.Generator.version7,
+      testIdGenerator = UUID.Generator.version7
+    )
+
+  end TestData
+
+  case class EngineObservation(
+    tickProvider: ManualTickProvider[IO],
+    reporter: InMemoryReporter[IO],
+    entryPoint: TestEntryPoint,
+    engine: TestEngine[IO]
+  )
+
+end TestEngineTests
diff --git a/modules/test-data/src/test/scala/support/Generators.scala b/modules/test-data/src/test/scala/support/Generators.scala
index 6d6bef6..96d10fc 100644
--- a/modules/test-data/src/test/scala/support/Generators.scala
+++ b/modules/test-data/src/test/scala/support/Generators.scala
@@ -64,16 +64,24 @@ object Generators:
       )
 
   val GenTestExecution: Gen[TestExecution] =
-    Gen.boolean().map(passed => InputGenTestExecution.generate(passed))
+    Gen.boolean().satisfy(InputGenTestExecution)
 
   val GenTestExecutionPassed: Gen[TestExecution] =
-    Gen.single(true).map(InputGenTestExecution.generate)
+    InputGenTestExecution.toGen(true)
 
   val GenTestExecutionFailed: Gen[TestExecution] =
-    Gen.single(false).map(InputGenTestExecution.generate)
+    InputGenTestExecution.toGen(false)
 
   given Generated[TestExecution] = Generated.of(GenTestExecution)
 
+  val GenTestSuite: Gen[TestSuite] =
+    for
+      pid  <- GenPermanentId
+      name <- Gen.string.alphaNumeric(Size.fixed(8))
+    yield TestSuite(pid, name, None)
+
+  given Generated[TestSuite] = Generated.of(GenTestSuite)
+
   def testExecutionId(): TestExecution.Id = GenTestExecutionId.gen()
 
   def permanentId(): PermanentId = GenPermanentId.gen()
@@ -91,9 +99,11 @@ object Generators:
   def testExecution(): TestExecution = GenTestExecution.gen()
 
   def testExecutionPassed(): TestExecution =
-    InputGenTestExecution.generate(true)
+    GenTestExecutionPassed.gen()
 
   def testExecutionFailed(): TestExecution =
-    InputGenTestExecution.generate(false)
+    GenTestExecutionFailed.gen()
+
+  def testSuite(): TestSuite = GenTestSuite.gen()
 
 end Generators
diff --git a/modules/test-support/src/test/scala/support/TestEntryPoint.scala b/modules/test-support/src/test/scala/support/TestEntryPoint.scala
new file mode 100644
index 0000000..f4f167b
--- /dev/null
+++ b/modules/test-support/src/test/scala/support/TestEntryPoint.scala
@@ -0,0 +1,48 @@
+package support
+
+import cats.effect.IO
+import cats.effect.kernel.Resource
+import cats.effect.std.MapRef
+import natchez.EntryPoint
+import natchez.Kernel
+import natchez.Span
+import natchez.Span.Options
+
+final class TestEntryPoint private (
+  spans: MapRef[IO, String, Option[TestSpan]]
+) extends EntryPoint[IO]:
+
+  def getSpan(name: String): IO[Option[TestSpan]] =
+    spans(name).get
+
+  override def root(
+    name: String,
+    options: Options
+  ): Resource[IO, Span[IO]] =
+    TestSpan
+      .provisionRoot(name, spans)
+      .evalTap(span => spans.setKeyValue(name, span))
+
+  override def continue(
+    name: String,
+    kernel: Kernel,
+    options: Options
+  ): Resource[IO, Span[IO]] =
+    throw new IllegalStateException("Not allowed for testing.")
+
+  override def continueOrElseRoot(
+    name: String,
+    kernel: Kernel,
+    options: Options
+  ): Resource[IO, Span[IO]] =
+    throw new IllegalStateException("Not allowed for testing.")
+
+object TestEntryPoint:
+
+  def initialize(): IO[TestEntryPoint] =
+    MapRef.apply[IO, String, TestSpan].map(spans => new TestEntryPoint(spans))
+
+  def provision(): Resource[IO, TestEntryPoint] =
+    Resource.make(initialize())(_ => IO.unit)
+
+end TestEntryPoint
diff --git a/modules/test-support/src/test/scala/support/TestSpan.scala b/modules/test-support/src/test/scala/support/TestSpan.scala
new file mode 100644
index 0000000..7f9aef0
--- /dev/null
+++ b/modules/test-support/src/test/scala/support/TestSpan.scala
@@ -0,0 +1,93 @@
+package support
+
+import cats.effect.IO
+import cats.effect.kernel.Resource
+import cats.effect.std.MapRef
+import java.net.URI
+import java.util.UUID
+import natchez.Kernel
+import natchez.Span
+import natchez.Span.Options
+import natchez.TraceValue
+
+final class TestSpan private (
+  val name: String,
+  val rawTraceId: String,
+  val rawSpanId: String,
+  baggage: MapRef[IO, String, Option[TraceValue]],
+  spans: MapRef[IO, String, Option[TestSpan]]
+) extends Span[IO]:
+
+  override def put(fields: (String, TraceValue)*): IO[Unit] =
+    fields.map { case (k, v) => baggage.setKeyValue(k, v) }.sequence.as(())
+
+  override def log(fields: (String, TraceValue)*): IO[Unit] = IO.unit
+
+  override def log(event: String): IO[Unit] = IO.unit
+
+  override def attachError(
+    err: Throwable,
+    fields: (String, TraceValue)*
+  ): IO[Unit] = IO.unit
+
+  override def kernel: IO[Kernel] = IO(Kernel(Map.empty))
+
+  override def span(
+    name: String,
+    options: Options
+  ): Resource[IO, Span[IO]] =
+    TestSpan
+      .provision(name, rawTraceId, TestSpan.makeSpanId(), spans)
+      .evalTap(span => spans.setKeyValue(name, span))
+
+  override def traceId: IO[Option[String]] = IO(Some(rawTraceId))
+
+  override def spanId: IO[Option[String]] = IO(Some(rawSpanId))
+
+  override def traceUri: IO[Option[URI]] = IO(None)
+
+object TestSpan:
+
+  def initializeRoot(
+    name: String,
+    spans: MapRef[IO, String, Option[TestSpan]]
+  ): IO[TestSpan] =
+    initialize(name, makeTraceId(), makeSpanId(), spans)
+
+  def initialize(
+    name: String,
+    traceId: String,
+    spanId: String,
+    spans: MapRef[IO, String, Option[TestSpan]]
+  ): IO[TestSpan] =
+    MapRef.apply[IO, String, TraceValue].map { baggage =>
+      new TestSpan(
+        name = name,
+        rawTraceId = traceId,
+        rawSpanId = spanId,
+        baggage = baggage,
+        spans = spans
+      )
+    }
+
+  def provisionRoot(
+    name: String,
+    spans: MapRef[IO, String, Option[TestSpan]]
+  ): Resource[IO, TestSpan] =
+    provision(name, makeTraceId(), makeSpanId(), spans)
+
+  def provision(
+    name: String,
+    traceId: String,
+    spanId: String,
+    spans: MapRef[IO, String, Option[TestSpan]]
+  ): Resource[IO, TestSpan] =
+    Resource.make(initialize(name, traceId, spanId, spans))(_ => IO.unit)
+
+  private def makeTraceId(): String =
+    UUID.randomUUID().toString().filterNot(_ == '-')
+
+  private def makeSpanId(): String =
+    makeTraceId().take(16)
+
+end TestSpan