Load classes using the test's own ClassLoader

Prior to this commit, the extensions supporting @MethodSource,
@EnabledIf, and @DisabledIf failed to load an external class if the
external class was not visible to JUnit's default ClassLoader.

This commit addresses those issues by loading external classes using
the ClassLoader obtained from the test class or falling back to JUnit's
default ClassLoader if the test's ClassLoader cannot be obtained.

This allows JUnit to find the classes while running in a custom
ClassLoader arrangement -- for example, inside an OSGi framework.

Closes #3292
Closes #3279
Closes #3280

Author: chrisr3

documentation/src/docs/asciidoc/release-notes/release-notes-5.10.0-M1.adoc

@@ -15,7 +15,8 @@ repository on GitHub.
 
 ==== Bug Fixes
 
-* ❓
+* Use a test class's own classloader to search for `@MethodSource` and `MethodBasedCondition` methods.
+  This allows these features to work correctly inside an OSGi framework.
 
 ==== Deprecations and Breaking Changes
 

junit-jupiter-api/src/main/java/org/junit/jupiter/api/condition/MethodBasedCondition.java

@@ -57,13 +57,14 @@ public ConditionEvaluationResult evaluateExecutionCondition(ExtensionContext con
 	}
 
 	private Method getConditionMethod(String fullyQualifiedMethodName, ExtensionContext context) {
+		final Class<?> testClass = context.getRequiredTestClass();
 		if (!fullyQualifiedMethodName.contains("#")) {
-			return findMethod(context.getRequiredTestClass(), fullyQualifiedMethodName);
+			return findMethod(testClass, fullyQualifiedMethodName);
 		}
 		String[] methodParts = ReflectionUtils.parseFullyQualifiedMethodName(fullyQualifiedMethodName);
 		String className = methodParts[0];
 		String methodName = methodParts[1];
-		Class<?> clazz = ReflectionUtils.tryToLoadClass(className).getOrThrow(
+		Class<?> clazz = ReflectionUtils.tryToLoadClass(className, testClass.getClassLoader()).getOrThrow(
 			cause -> new JUnitException(format("Could not load class [%s]", className), cause));
 		return findMethod(clazz, methodName);
 	}

junit-jupiter-params/src/main/java/org/junit/jupiter/params/provider/MethodArgumentsProvider.java

@@ -73,7 +73,7 @@ private static Method findFactoryMethod(Class<?> testClass, Method testMethod, S
 		}
 
 		// Find factory method using fully-qualified name.
-		Method factoryMethod = findFactoryMethodByFullyQualifiedName(testMethod, factoryMethodName);
+		Method factoryMethod = findFactoryMethodByFullyQualifiedName(testClass, testMethod, factoryMethodName);
 
 		// Ensure factory method has a valid return type and is not a test method.
 		Preconditions.condition(isFactoryMethod.test(factoryMethod), () -> format(
@@ -103,12 +103,13 @@ private static boolean looksLikeAFullyQualifiedMethodName(String factoryMethodNa
 		return true;
 	}
 
-	private static Method findFactoryMethodByFullyQualifiedName(Method testMethod, String fullyQualifiedMethodName) {
+	private static Method findFactoryMethodByFullyQualifiedName(Class<?> testClass, Method testMethod,
+			String fullyQualifiedMethodName) {
 		String[] methodParts = ReflectionUtils.parseFullyQualifiedMethodName(fullyQualifiedMethodName);
 		String className = methodParts[0];
 		String methodName = methodParts[1];
 		String methodParameters = methodParts[2];
-		Class<?> clazz = loadRequiredClass(className);
+		Class<?> clazz = loadRequiredClass(className, testClass.getClassLoader());
 
 		// Attempt to find an exact match first.
 		Method factoryMethod = ReflectionUtils.findMethod(clazz, methodName, methodParameters).orElse(null);
@@ -170,8 +171,8 @@ private static boolean isTestMethod(Method candidate) {
 				|| isAnnotated(candidate, TestFactory.class);
 	}
 
-	private static Class<?> loadRequiredClass(String className) {
-		return ReflectionUtils.tryToLoadClass(className).getOrThrow(
+	private static Class<?> loadRequiredClass(String className, ClassLoader classLoader) {
+		return ReflectionUtils.tryToLoadClass(className, classLoader).getOrThrow(
 			cause -> new JUnitException(format("Could not load class [%s]", className), cause));
 	}