Add tests for MethodInvoker behavior in the TestContext framework

See spring-projectsgh-31199

spring-test/src/test/java/org/springframework/test/context/TestContextManagerMethodInvokerTests.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.test.context;
+
+import java.lang.reflect.Method;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.util.ReflectionUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.context.MethodInvoker.DEFAULT_INVOKER;
+
+/**
+ * JUnit Jupiter based unit test for {@link TestContextManager}, which verifies proper
+ * {@link MethodInvoker} behavior.
+ *
+ * @author Sam Brannen
+ * @since 6.1
+ */
+class TestContextManagerMethodInvokerTests {
+
+	private static final MethodInvoker customMethodInvoker = (method, target) -> null;
+
+	private final TestContextManager testContextManager = new TestContextManager(TestCase.class);
+
+	private final Method testMethod = ReflectionUtils.findMethod(TestCase.class, "testMethod");
+
+
+	@Test
+	void methodInvokerState() throws Exception {
+		assertThat(testContextManager.getTestExecutionListeners()).singleElement().isInstanceOf(DemoExecutionListener.class);
+
+		assertMethodInvokerState(testContextManager::beforeTestClass);
+
+		assertMethodInvokerState(() -> testContextManager.prepareTestInstance(this));
+
+		assertMethodInvokerState(() -> testContextManager.beforeTestMethod(this, testMethod));
+
+		assertMethodInvokerState(() -> testContextManager.beforeTestExecution(this, testMethod));
+
+		assertMethodInvokerState(() -> testContextManager.afterTestExecution(this, testMethod, null));
+
+		assertMethodInvokerState(() -> testContextManager.afterTestMethod(this, testMethod, null));
+
+		assertMethodInvokerState(testContextManager::afterTestClass);
+	}
+
+	private void assertMethodInvokerState(Executable callback) throws Exception {
+		testContextManager.getTestContext().setMethodInvoker(customMethodInvoker);
+		callback.execute();
+		assertThat(testContextManager.getTestContext().getMethodInvoker()).isSameAs(DEFAULT_INVOKER);
+	}
+
+
+	@TestExecutionListeners(DemoExecutionListener.class)
+	private static class TestCase {
+
+		@SuppressWarnings("unused")
+		void testMethod() {
+		}
+	}
+
+	private static class DemoExecutionListener implements TestExecutionListener {
+
+		@Override
+		public void beforeTestClass(TestContext testContext) {
+			assertThat(testContext.getMethodInvoker()).isSameAs(customMethodInvoker);
+		}
+
+		@Override
+		public void prepareTestInstance(TestContext testContext) throws Exception {
+			assertThat(testContext.getMethodInvoker()).isSameAs(customMethodInvoker);
+		}
+
+		@Override
+		public void beforeTestMethod(TestContext testContext) {
+			assertThat(testContext.getMethodInvoker()).isSameAs(customMethodInvoker);
+		}
+
+		@Override
+		public void beforeTestExecution(TestContext testContext) {
+			assertThat(testContext.getMethodInvoker()).isSameAs(customMethodInvoker);
+		}
+
+		@Override
+		public void afterTestExecution(TestContext testContext) {
+			assertThat(testContext.getMethodInvoker()).isSameAs(customMethodInvoker);
+		}
+
+		@Override
+		public void afterTestMethod(TestContext testContext) {
+			assertThat(testContext.getMethodInvoker()).isSameAs(customMethodInvoker);
+		}
+
+		@Override
+		public void afterTestClass(TestContext testContext) {
+			assertThat(testContext.getMethodInvoker()).isSameAs(customMethodInvoker);
+		}
+
+	}
+
+	private interface Executable {
+
+		void execute() throws Exception;
+
+	}
+
+}