Add Kotlin code examples to last writing tests topics

documentation/modules/ROOT/pages/writing-tests/tagging-and-filtering.adoc

@@ -5,10 +5,26 @@ used to filter xref:running-tests/intro.adoc[test discovery and execution]. Plea
 xref:running-tests/tags.adoc[] section for more information about tag support in the JUnit
 Platform.
 
+[tabs]
+====
+Java::
++
+--
 [source,java,indent=0]
 ----
 include::example$java/example/TaggingDemo.java[tags=user_guide]
 ----
+--
+
+Kotlin::
++
+--
+[source,kotlin,indent=0]
+----
+include::example$kotlin/example/kotlin/TaggingDemo.kt[tags=user_guide]
+----
+--
+====
 
 TIP: See xref:writing-tests/annotations.adoc#annotations[Meta-Annotations and Composed Annotations] for examples demonstrating how to create
 custom annotations for tags.

documentation/modules/ROOT/pages/writing-tests/test-execution-order.adoc

@@ -41,10 +41,26 @@ NOTE: See also: xref:extensions/relative-execution-order-of-user-code-and-extens
 The following example demonstrates how to guarantee that test methods are executed in the
 order specified via the `@Order` annotation.
 
+[tabs]
+====
+Java::
++
+--
 [source,java,indent=0]
 ----
 include::example$java/example/OrderedTestsDemo.java[tags=user_guide]
 ----
+--
+
+Kotlin::
++
+--
+[source,kotlin,indent=0]
+----
+include::example$kotlin/example/kotlin/OrderedTestsDemo.kt[tags=user_guide]
+----
+--
+====
 
 [[methods-default]]
 === Setting the Default Method Orderer
@@ -132,7 +148,23 @@ Note that a local `@TestClassOrder` declaration always overrides an inherited
 The following example demonstrates how to guarantee that `@Nested` test classes are
 executed in the order specified via the `@Order` annotation.
 
+[tabs]
+====
+Java::
++
+--
 [source,java,indent=0]
 ----
 include::example$java/example/OrderedNestedTestClassesDemo.java[tags=user_guide]
 ----
+--
+
+Kotlin::
++
+--
+[source,kotlin,indent=0]
+----
+include::example$kotlin/example/kotlin/OrderedNestedTestClassesDemo.kt[tags=user_guide]
+----
+--
+====

documentation/src/test/kotlin/example/kotlin/ExternalFieldSourceDemo.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2015-2026 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package example.kotlin
+
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.FieldSource
+
+class ExternalFieldSourceDemo {
+    // tag::external_field_FieldSource_example[]
+    @ParameterizedTest
+    @FieldSource("example.kotlin.FruitUtils#tropicalFruits")
+    fun testWithExternalFieldSource(tropicalFruit: String) {
+        // test with tropicalFruit
+    }
+    // end::external_field_FieldSource_example[]
+}
+
+object FruitUtils {
+    @JvmField
+    val tropicalFruits: List<String> = listOf("pineapple", "kiwi")
+}

documentation/src/test/kotlin/example/kotlin/ExternalMethodSourceDemo.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2015-2026 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package example.kotlin
+
+// tag::external_MethodSource_example[]
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.MethodSource
+
+class ExternalMethodSourceDemo {
+    @ParameterizedTest
+    @MethodSource("example.kotlin.StringsProviders#tinyStrings")
+    fun testWithExternalMethodSource(tinyString: String) {
+        // test with tiny string
+    }
+}
+
+object StringsProviders {
+    @JvmStatic
+    fun tinyStrings() = sequenceOf(".", "oo", "OOO")
+}
+// end::external_MethodSource_example[]

documentation/src/test/kotlin/example/kotlin/MethodSourceParameterResolutionDemo.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2015-2026 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package example.kotlin
+
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.TestInstance
+import org.junit.jupiter.api.TestInstance.Lifecycle.PER_CLASS
+import org.junit.jupiter.api.extension.ExtensionContext
+import org.junit.jupiter.api.extension.ParameterContext
+import org.junit.jupiter.api.extension.ParameterResolver
+import org.junit.jupiter.api.extension.RegisterExtension
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments.arguments
+import org.junit.jupiter.params.provider.MethodSource
+
+@TestInstance(PER_CLASS)
+class MethodSourceParameterResolutionDemo {
+    // tag::parameter_resolution_MethodSource_example[]
+    @JvmField
+    @RegisterExtension
+    val integerResolver = IntegerResolver()
+
+    @ParameterizedTest
+    @MethodSource("factoryMethodWithArguments")
+    fun testWithFactoryMethodWithArguments(argument: String) {
+        assertTrue(argument.startsWith("2"))
+    }
+
+    fun factoryMethodWithArguments(quantity: Int) =
+        sequenceOf(
+            arguments("$quantity apples"),
+            arguments("$quantity lemons")
+        )
+
+    class IntegerResolver : ParameterResolver {
+        override fun supportsParameter(
+            parameterContext: ParameterContext,
+            extensionContext: ExtensionContext
+        ): Boolean = parameterContext.parameter.type == Int::class.javaPrimitiveType
+
+        override fun resolveParameter(
+            parameterContext: ParameterContext,
+            extensionContext: ExtensionContext
+        ): Any = 2
+    }
+    // end::parameter_resolution_MethodSource_example[]
+}

documentation/src/test/kotlin/example/kotlin/OrderedNestedTestClassesDemo.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2015-2026 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package example.kotlin
+
+// tag::user_guide[]
+import org.junit.jupiter.api.ClassOrderer
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Order
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.TestClassOrder
+
+@TestClassOrder(ClassOrderer.OrderAnnotation::class)
+class OrderedNestedTestClassesDemo {
+    @Nested
+    @Order(1)
+    inner class PrimaryTests {
+        @Test
+        fun test1() {
+        }
+    }
+
+    @Nested
+    @Order(2)
+    inner class SecondaryTests {
+        @Test
+        fun test2() {
+        }
+    }
+}
+// end::user_guide[]

documentation/src/test/kotlin/example/kotlin/OrderedTestsDemo.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2015-2026 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package example.kotlin
+
+// tag::user_guide[]
+import org.junit.jupiter.api.MethodOrderer.OrderAnnotation
+import org.junit.jupiter.api.Order
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.TestMethodOrder
+
+@TestMethodOrder(OrderAnnotation::class)
+class OrderedTestsDemo {
+    @Test
+    @Order(1)
+    fun nullValues() {
+        // perform assertions against null values
+    }
+
+    @Test
+    @Order(2)
+    fun emptyValues() {
+        // perform assertions against empty values
+    }
+
+    @Test
+    @Order(3)
+    fun validValues() {
+        // perform assertions against valid values
+    }
+}
+// end::user_guide[]

documentation/src/test/kotlin/example/kotlin/ParameterizedClassDemo.kt

@@ -10,18 +10,114 @@
 
 package example.kotlin
 
+import example.util.StringUtils
 import org.junit.jupiter.api.Assertions.assertFalse
 import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.parallel.Execution
 import org.junit.jupiter.api.parallel.ExecutionMode.SAME_THREAD
 import org.junit.jupiter.params.Parameter
 import org.junit.jupiter.params.ParameterizedClass
 import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.CsvSource
 import org.junit.jupiter.params.provider.ValueSource
 import java.time.Duration
 
 class ParameterizedClassDemo {
+    // @formatter:off
+    @Nested
+    // tag::first_example[]
+    @ParameterizedClass
+    @ValueSource(strings = ["racecar", "radar", "able was I ere I saw elba"])
+    // end::first_example[]
+    inner
+    // tag::first_example[]
+    class PalindromeTests {
+        // end::first_example[]
+        // @formatter:on
+        // tag::first_example[]
+        @Parameter
+        lateinit var candidate: String
+
+        @Test
+        fun palindrome() {
+            assertTrue(StringUtils.isPalindrome(candidate))
+        }
+
+        @Test
+        fun reversePalindrome() {
+            val reverseCandidate = candidate.reversed()
+            assertTrue(StringUtils.isPalindrome(reverseCandidate))
+        }
+    }
+    // end::first_example[]
+
+    @Nested
+    inner class ConstructorInjection {
+        // @formatter:off
+        @Nested
+        // tag::constructor_injection[]
+        @ParameterizedClass
+        @CsvSource("apple, 23", "banana, 42")
+        // end::constructor_injection[]
+        inner
+        // tag::constructor_injection[]
+        class FruitTests(
+            private val fruit: String,
+            private val quantity: Int
+        ) {
+            // end::constructor_injection[]
+            // @formatter:on
+            // tag::constructor_injection[]
+            @Test
+            fun test() {
+                assertFruit(fruit)
+                assertQuantity(quantity)
+            }
+
+            @Test
+            fun anotherTest() {
+                // ...
+            }
+        }
+        // end::constructor_injection[]
+    }
+
+    @Nested
+    inner class FieldInjection {
+        // @formatter:off
+        @Nested
+        // tag::field_injection[]
+        @ParameterizedClass
+        @CsvSource("apple, 23", "banana, 42")
+        // end::field_injection[]
+        inner
+        // tag::field_injection[]
+        class FruitTests {
+            // end::field_injection[]
+            // @formatter:on
+            // tag::field_injection[]
+            @Parameter(0)
+            lateinit var fruit: String
+
+            @Parameter(1)
+            var quantity: Int = 0
+
+            @Test
+            fun test() {
+                assertFruit(fruit)
+                assertQuantity(quantity)
+            }
+
+            @Test
+            fun anotherTest() {
+                // ...
+            }
+        }
+        // end::field_injection[]
+    }
+
     // @formatter:off
     @Nested
     // tag::nested[]
@@ -58,7 +154,7 @@ class ParameterizedClassDemo {
 
     private fun assertFruit(fruit: String) {
         assertTrue(
-            listOf("apple", "banana", "cherry", "dewberry").contains(fruit)
+            fruit in listOf("apple", "banana", "cherry", "dewberry")
         ) { "not a fruit: $fruit" }
     }