Test Definition and Structure

/**
 * Creates a test with the specified label and assertion
 * @param label descriptive name for the test
 * @param assertion test logic returning TestResult or ZIO effect
 * @return test specification
 */
def test[R](label: String)(assertion: => ZIO[R, Any, TestResult]): Spec[R, Any]

import zio.test._

// Simple test with assertTrue
test("addition works correctly") {
  assertTrue(2 + 2 == 4)
}

// Effectful test
test("database connection") {
  for {
    connection <- Database.connect
    isValid <- connection.isValid
  } yield assertTrue(isValid)
}

// Test with custom assertion
test("list contains element") {
  val list = List(1, 2, 3, 4, 5)
  assert(list)(contains(3))
}

/**
 * Creates a test suite with the specified label and child specifications
 * @param label descriptive name for the suite
 * @param specs child test specifications (tests or nested suites)
 * @return suite specification
 */
def suite[R](label: String)(specs: Spec[R, Any]*): Spec[R, Any]

import zio.test._

// Simple suite with multiple tests
suite("Math Operations")(
  test("addition") { assertTrue(2 + 2 == 4) },
  test("multiplication") { assertTrue(3 * 4 == 12) },
  test("division") { assertTrue(10 / 2 == 5) }
)

// Nested suites
suite("API Tests")(
  suite("User Endpoints")(
    test("create user") { /* test logic */ },
    test("get user") { /* test logic */ },
    test("update user") { /* test logic */ }
  ),
  suite("Product Endpoints")(
    test("list products") { /* test logic */ },
    test("create product") { /* test logic */ }
  )
)

/**
 * Effectful test that may fail with TestFailure[E] or succeed with TestSuccess
 */
type ZTest[-R, +E] = ZIO[R, TestFailure[E], TestSuccess]

object ZTest {
  /**
   * Builds a test with an effectual assertion
   * @param label test label
   * @param assertion effectual test assertion
   * @return ZTest instance
   */
  def apply[R, E](label: String, assertion: => ZIO[R, E, TestResult]): ZIO[R, TestFailure[E], TestSuccess]
}

/**
 * A test specification that can be executed to produce test results
 * @tparam R environment required to run the specification
 * @tparam E error type that tests may fail with
 */
trait Spec[+R, +E] {
  /**
   * Apply a test aspect to this specification
   * @param aspect test aspect to apply
   * @return modified specification
   */
  def @@[R1 <: R](aspect: TestAspect[Nothing, R1, Nothing, Any]): Spec[R1, E]
  
  /**
   * Transform the environment of this specification
   * @param f transformation function
   * @return specification with transformed environment
   */
  def provideLayer[R0, R1, E1 >: E](layer: ZLayer[R0, E1, R1]): Spec[R0, E1]
}

import zio.test._
import zio.test.TestAspect._

// Apply timeout aspect to entire suite
suite("Database Tests")(
  test("slow query") { /* test logic */ },
  test("batch insert") { /* test logic */ }
) @@ timeout(30.seconds)

// Apply multiple aspects
suite("Integration Tests")(
  test("external API call") { /* test logic */ }
) @@ timeout(10.seconds) @@ eventually @@ flaky

/**
 * A single test case with metadata
 * @param label descriptive test name
 * @param test the test logic as ZIO effect
 * @param annotations metadata attached to the test
 */
case class SpecCase[+R, +E](
  label: String,
  test: ZIO[R, TestFailure[E], TestSuccess],
  annotations: TestAnnotationMap
)

/**
 * Abstract base class for ZIO test specifications
 * @tparam R environment type required by tests
 */
abstract class ZIOSpec[R] {
  /**
   * The test specification to execute
   */
  def spec: Spec[R, Any]
}

/**
 * Base class for test specs with standard test environment
 */
abstract class ZIOSpecDefault extends ZIOSpec[TestEnvironment] {
  /**
   * Test specification using default test environment
   */
  def spec: Spec[TestEnvironment, Any]
}

import zio.test._

// Using ZIOSpecDefault (recommended)
object MyTestSpec extends ZIOSpecDefault {
  def spec = suite("My Tests")(
    test("basic test") {
      assertTrue(1 + 1 == 2)
    }
  )
}

// Using ZIOSpec with custom environment
object CustomEnvSpec extends ZIOSpec[MyCustomEnv] {
  def spec = suite("Custom Environment Tests")(
    test("uses custom service") {
      for {
        result <- ZIO.serviceWithZIO[MyCustomService](_.doSomething())
      } yield assertTrue(result.isSuccess)
    }
  )
}

/**
 * Type class for constructing test suites from different input types
 */
trait SuiteConstructor[In] {
  type OutEnvironment
  type OutError
  
  def apply(in: In): Spec[OutEnvironment, OutError]
}

// Instances for common types
implicit def functionSuiteConstructor[A, In](implicit 
  constructor: TestConstructor[In]
): SuiteConstructor[A => In]

implicit def specSuiteConstructor[R, E]: SuiteConstructor[Spec[R, E]]

/**
 * Interface for running test specifications
 */
trait TestRunner[R, E] {
  def run(spec: Spec[R, E]): ZIO[R, Nothing, ExecutionEvent]
}

object TestRunner {
  def default[R, E]: TestRunner[R, E]
}

/**
 * Events emitted during test execution
 */
sealed trait ExecutionEvent

case class Test(labels: List[String], test: Either[TestFailure[Any], TestSuccess]) extends ExecutionEvent
case class SuiteStarted(labels: List[String]) extends ExecutionEvent
case class SuiteCompleted(labels: List[String]) extends ExecutionEvent
case class TestStarted(labels: List[String]) extends ExecutionEvent
case class TestCompleted[E](labels: List[String], result: Either[TestFailure[E], TestSuccess]) extends ExecutionEvent