Issue-829: Highlight multi-threading error in TestNG

Test has a per class lifecycle model and jgiven a per method
lifecycle model. Therefore, if
a field is used by several tests it gets continuously overwritten by the scenario setup on the different threads leading to execution error. As a quick-fix, we are highlighting that this problem exists.

Signed-off-by: l-1sqared <30831153+l-1squared@users.noreply.github.com>

jgiven-testng/src/main/java/com/tngtech/jgiven/testng/IncompatibleMultithreadingChecker.java

@@ -0,0 +1,43 @@
+package com.tngtech.jgiven.testng;
+
+import com.tngtech.jgiven.annotation.ScenarioStage;
+import com.tngtech.jgiven.exception.JGivenWrongUsageException;
+import com.tngtech.jgiven.impl.util.ReflectionUtil;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import org.testng.ITestResult;
+import org.testng.annotations.Test;
+
+class IncompatibleMultithreadingChecker {
+
+    @SuppressWarnings("checkstyle:AbbreviationAsWordInName")
+    public void checkIncompatibleMultiThreading(ITestResult paramITestResult) {
+        Method testMethod = paramITestResult.getMethod().getConstructorOrMethod().getMethod();
+        boolean isMultiThreaded = isMultiThreaded(paramITestResult.getClass(), testMethod);
+        boolean hasInjectedStages = hasInjectedStages(paramITestResult.getClass());
+
+        if (isMultiThreaded && hasInjectedStages) {
+            throw new JGivenWrongUsageException("JGiven does not support using multi-threading and stage injection"
+                + "in TestNG at the same time due to their different lifecycle models. "
+                + "Please switch to single threaded execution or provide stages via inheriting from ScenarioTest");
+        }
+    }
+
+    private boolean isMultiThreaded(Class<?> testClass, Method testMethod) {
+        List<Test> testAnnotations = new ArrayList<>();
+        testAnnotations.addAll(Collections.singletonList(testClass.getAnnotation(Test.class)));
+        testAnnotations.addAll(Collections.singletonList(testMethod.getAnnotation(Test.class)));
+        return testAnnotations.stream().anyMatch(test -> !test.singleThreaded());
+    }
+
+    private boolean hasInjectedStages(Class<?> testClass) {
+        ThreadLocal<Boolean> hasInjectedStage = new ThreadLocal<>();
+        ReflectionUtil.forEachSuperClass(testClass, clazz ->
+            hasInjectedStage.set(Arrays.stream(clazz.getDeclaredFields())
+                .anyMatch(field -> field.isAnnotationPresent(ScenarioStage.class))));
+        return hasInjectedStage.get();
+    }
+}

jgiven-testng/src/main/java/com/tngtech/jgiven/testng/ScenarioTestListener.java

@@ -28,6 +28,7 @@ public class ScenarioTestListener implements ITestListener {
 
     @Override
     public void onTestStart( ITestResult paramITestResult ) {
+        new IncompatibleMultithreadingChecker().checkIncompatibleMultiThreading(paramITestResult);
         Object instance = paramITestResult.getInstance();
 
         ScenarioBase scenario;