Using NoSystemOutListener prevents single tests from being executed (#…

…3923)

Fixes #3303

kotest-extensions/src/jvmMain/kotlin/io/kotest/extensions/system/NoSystemOutExtensions.kt

@@ -1,7 +1,8 @@
 package io.kotest.extensions.system
 
 import io.kotest.core.listeners.TestListener
-import io.kotest.core.spec.Spec
+import io.kotest.core.test.TestCase
+import io.kotest.core.test.TestResult
 import java.io.ByteArrayOutputStream
 import java.io.PrintStream
 
@@ -12,44 +13,56 @@ class SystemErrWriteException(val str: String?) : RuntimeException()
  * A [TestListener] that throws an error if anything is written to standard out.
  */
 object NoSystemOutListener : TestListener {
-   private fun setup() {
-      val out = ByteArrayOutputStream()
-      System.setOut(object : PrintStream(out) {
-         private fun error(a: Any?): Nothing = throw SystemOutWriteException(a?.toString())
-         override fun print(b: Boolean) = error(b)
-         override fun print(c: Char) = error(c)
-         override fun print(i: Int) = error(i)
-         override fun print(l: Long) = error(l)
-         override fun print(s: String) = error(s)
-         override fun print(o: Any) = error(o)
-         override fun print(c: CharArray) = error(c)
-         override fun print(d: Double) = error(d)
-         override fun print(f: Float) = error(f)
-      })
+
+   private val stream = object : PrintStream(ByteArrayOutputStream()) {
+      private fun error(a: Any?): Nothing = throw SystemOutWriteException(a?.toString())
+      override fun print(b: Boolean) = error(b)
+      override fun print(c: Char) = error(c)
+      override fun print(i: Int) = error(i)
+      override fun print(l: Long) = error(l)
+      override fun print(s: String) = error(s)
+      override fun print(o: Any) = error(o)
+      override fun print(c: CharArray) = error(c)
+      override fun print(d: Double) = error(d)
+      override fun print(f: Float) = error(f)
    }
 
-   override suspend fun beforeSpec(spec: Spec) = setup()
+   private val stdout = System.out
+
+   override suspend fun beforeTest(testCase: TestCase) {
+      System.setOut(stream)
+   }
+
+   override suspend fun afterTest(testCase: TestCase, result: TestResult) {
+      System.setOut(stdout)
+   }
 }
 
 /**
  * A [TestListener] that throws an error if anything is written to standard err.
  */
 object NoSystemErrListener : TestListener {
-   private fun setup() {
-      val out = ByteArrayOutputStream()
-      System.setErr(object : PrintStream(out) {
-         private fun error(a: Any?): Nothing = throw SystemErrWriteException(a?.toString())
-         override fun print(b: Boolean) = error(b)
-         override fun print(c: Char) = error(c)
-         override fun print(i: Int) = error(i)
-         override fun print(l: Long) = error(l)
-         override fun print(s: String) = error(s)
-         override fun print(o: Any) = error(o)
-         override fun print(c: CharArray) = error(c)
-         override fun print(d: Double) = error(d)
-         override fun print(f: Float) = error(f)
-      })
+
+   private val stream = object : PrintStream(ByteArrayOutputStream()) {
+      private fun error(a: Any?): Nothing = throw SystemErrWriteException(a?.toString())
+      override fun print(b: Boolean) = error(b)
+      override fun print(c: Char) = error(c)
+      override fun print(i: Int) = error(i)
+      override fun print(l: Long) = error(l)
+      override fun print(s: String) = error(s)
+      override fun print(o: Any) = error(o)
+      override fun print(c: CharArray) = error(c)
+      override fun print(d: Double) = error(d)
+      override fun print(f: Float) = error(f)
    }
 
-   override suspend fun beforeSpec(spec: Spec) = setup()
+   private val stderr = System.err
+
+   override suspend fun beforeTest(testCase: TestCase) {
+      System.setErr(stream)
+   }
+
+   override suspend fun afterTest(testCase: TestCase, result: TestResult) {
+      System.setErr(stderr)
+   }
 }

kotest-extensions/src/jvmTest/kotlin/com/sksamuel/kt/extensions/system/NoSystemOutOrErrTest.kt

@@ -1,30 +1,30 @@
-//package com.sksamuel.kt.extensions.system
-//
-//import io.kotest.assertions.throwables.shouldThrow
-//import io.kotest.core.annotation.Isolate
-//import io.kotest.extensions.system.NoSystemErrListener
-//import io.kotest.extensions.system.NoSystemOutListener
-//import io.kotest.extensions.system.SystemErrWriteException
-//import io.kotest.extensions.system.SystemOutWriteException
-//import io.kotest.core.spec.style.StringSpec
-//
-//@Isolate
-//class NoSystemOutOrErrTest : StringSpec() {
-//
-//  override fun listeners() = listOf(NoSystemOutListener, NoSystemErrListener)
-//
-//  init {
-//
-//    "System.out should throw an exception when the listener is added" {
-//      shouldThrow<SystemOutWriteException> {
-//        println("boom")
-//      }
-//    }
-//
-//    "System.err should throw an exception when the listener is added" {
-//      shouldThrow<SystemErrWriteException> {
-//        System.err.println("boom")
-//      }
-//    }
-//  }
-//}
+package com.sksamuel.kt.extensions.system
+
+import io.kotest.assertions.throwables.shouldThrow
+import io.kotest.core.annotation.Isolate
+import io.kotest.extensions.system.NoSystemErrListener
+import io.kotest.extensions.system.NoSystemOutListener
+import io.kotest.extensions.system.SystemErrWriteException
+import io.kotest.extensions.system.SystemOutWriteException
+import io.kotest.core.spec.style.StringSpec
+
+@Isolate
+class NoSystemOutOrErrTest : StringSpec() {
+
+  override fun listeners() = listOf(NoSystemOutListener, NoSystemErrListener)
+
+  init {
+
+    "System.out should throw an exception when the listener is added" {
+      shouldThrow<SystemOutWriteException> {
+        println("boom")
+      }
+    }
+
+    "System.err should throw an exception when the listener is added" {
+      shouldThrow<SystemErrWriteException> {
+        System.err.println("boom")
+      }
+    }
+  }
+}