Use system classloader as TCCL for storing pre-test config

core/deployment/src/main/java/io/quarkus/test/junit/classloading/FacadeClassLoader.java

@@ -633,18 +633,28 @@ private AppMakerHelper.DumbHolder makeClassLoader(String key, Class requiredTest
         AppMakerHelper.DumbHolder holder = appMakerHelper.getStartupAction(requiredTestClass,
                 curatedApplication, isAuxiliaryApplication, profile);
 
+        ClassLoader original = Thread.currentThread().getContextClassLoader();
+        // See comments on AbstractJVMTestExtension#evaluateExecutionCondition for why this is the system classloader
+        Thread.currentThread().setContextClassLoader(ClassLoader.getSystemClassLoader());
+
         QuarkusClassLoader loader = (QuarkusClassLoader) holder.startupAction()
                 .getClassLoader();
 
-        Class<?> configProviderResolverClass = loader.loadClass(ConfigProviderResolver.class.getName());
-        Object configProviderResolver = configProviderResolverClass.getMethod("instance").invoke(null);
-
-        Class<?> testConfigProviderResolverClass = loader.loadClass(QuarkusTestConfigProviderResolver.class.getName());
-        Object testConfigProviderResolver = testConfigProviderResolverClass.getDeclaredConstructor(ClassLoader.class)
-                .newInstance(loader);
-
-        configProviderResolverClass.getDeclaredMethod("setInstance", configProviderResolverClass).invoke(null,
-                testConfigProviderResolver);
+        try {
+            Class<?> configProviderResolverClass = loader.loadClass(ConfigProviderResolver.class.getName());
+            Object configProviderResolver = configProviderResolverClass.getMethod("instance")
+                    .invoke(null);
+
+            Class<?> testConfigProviderResolverClass = loader.loadClass(QuarkusTestConfigProviderResolver.class.getName());
+            Object testConfigProviderResolver = testConfigProviderResolverClass.getDeclaredConstructor(ClassLoader.class)
+                    .newInstance(loader);
+
+            configProviderResolverClass.getDeclaredMethod("setInstance", configProviderResolverClass)
+                    .invoke(null,
+                            testConfigProviderResolver);
+        } finally {
+            Thread.currentThread().setContextClassLoader(original);
+        }
 
         // TODO is this a good idea?
         // TODO without this, the parameter dev mode tests regress, but it feels kind of wrong - is there some use of TCCL in JUnitRunner we need to find

test-framework/junit5/src/main/java/io/quarkus/test/junit/AbstractJvmQuarkusTestExtension.java

@@ -261,21 +261,30 @@ public ConditionEvaluationResult evaluateExecutionCondition(ExtensionContext con
         System.out.println("OK smallrye " + SmallRyeConfig.class.getClassLoader());
 
         // TODO this should not be necessary, because we want the config provider to be for our class
-        //        ClassLoader original = Thread.currentThread().getContextClassLoader();
+        // TODO stale comments below
+        // At this point, the TCCL is usually the FacadeClassLoader; trying to do getConfig with that TCCL fails with java.util.ServiceConfigurationError: io.smallrye.config.SmallRyeConfigFactory: io.quarkus.runtime.configuration.QuarkusConfigFactory not a subtype
+        // If we set the TCCL to be this.getClass().getClassLoader(), get config succeeds, but config.getConfigMapping(TestConfig.class) fails, because the mapping was registered when the TCCL was the FacadeClassLoader
+
+        // At this point, the TCCL is usually the FacadeClassLoader, but sometimes it's a deployment classloader (for multimodule tests), or the runtime classloader (for nested tests)
+        // Getting back to the FacadeClassLoader is non-trivial. We can't use a simple singleton on the class, because we will be accessing it from different classloaders.
+        // We can't have a hook back from the runtime classloader to the facade classloader, because
+        // when evaluating execution conditions for native tests, the test will have been loaded with the system classloader, not the runtime classloader.
+        // The one classloader we can reliably get to when evaluating test execution is the system classloader, so hook our config on that.
+
+        ClassLoader original = Thread.currentThread().getContextClassLoader();
         //        Thread.currentThread().setContextClassLoader(this.getClass().getClassLoader());
+        Thread.currentThread().setContextClassLoader(ClassLoader.getSystemClassLoader());
 
         //        SmallRyeConfig config = ConfigProvider.getConfig().unwrap(SmallRyeConfig.class);
         //        TestConfig testConfig = config.getConfigMapping(TestConfig.class);
 
-        // At this point, the TCCL is the FacadeClassLoader; trying to do getConfig with that TCCL fails with java.util.ServiceConfigurationError: io.smallrye.config.SmallRyeConfigFactory: io.quarkus.runtime.configuration.QuarkusConfigFactory not a subtype
-        // If we set the TCCL to be this.getClass().getClassLoader(), get config succeeds, but config.getConfigMapping(TestConfig.class) fails, because the mapping was registered when the TCCL was the FacadeClassLoader
         TestConfig testConfig = ConfigProvider.getConfig().unwrap(SmallRyeConfig.class).getConfigMapping(TestConfig.class);
 
         Optional<List<String>> tags = testConfig.profile().tags();
         if (tags.isEmpty() || tags.get().isEmpty()) {
             return ConditionEvaluationResult.enabled("No Quarkus Test Profile tags");
         }
-        //        Thread.currentThread().setContextClassLoader(original);
+        Thread.currentThread().setContextClassLoader(original);
 
         Class<? extends QuarkusTestProfile> testProfile = getQuarkusTestProfile(context);
         if (testProfile == null) {