move user guide example to ParameterizedTestDemo

Issue #3708

Author: JonasJebing

documentation/src/docs/asciidoc/user-guide/writing-tests.adoc

@@ -2041,11 +2041,7 @@ use the `argumentCountValidation` attribute of the `@ParameterizedTest` annotati
 
 [source,java,indent=0]
 ----
-	@ParameterizedTest(argumentCountValidation = ArgumentCountValidationMode.STRICT)
-	@CsvSource({ "42, -666" })
-	void testWithArgumentCountValidation(int number) {
-		assertTrue(number > 0);
-	}
+include::{testDir}/example/ParameterizedTestDemo.java[tags=argument_count_validation]
 ----
 
 [[writing-tests-parameterized-tests-argument-conversion]]

documentation/src/test/java/example/ParameterizedTestDemo.java

@@ -51,6 +51,7 @@
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.junit.jupiter.api.extension.ParameterContext;
 import org.junit.jupiter.api.parallel.Execution;
+import org.junit.jupiter.params.ArgumentCountValidationMode;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.aggregator.AggregateWith;
 import org.junit.jupiter.params.aggregator.ArgumentsAccessor;
@@ -607,4 +608,13 @@ static Stream<String> otherProvider() {
 		return Stream.of("bar");
 	}
 	// end::repeatable_annotations[]
+
+	@extensions.ExpectToFail
+	// tag::argument_count_validation[]
+	@ParameterizedTest(argumentCountValidation = ArgumentCountValidationMode.STRICT)
+	@CsvSource({ "42, -666" })
+	void testWithArgumentCountValidation(int number) {
+		assertTrue(number > 0);
+	}
+	// end::argument_count_validation[]
 }