Add tests for SimpleInstantiationStrategy

spring-beans/src/test/java/org/springframework/beans/factory/support/SimpleInstantiationStrategyTests.java

@@ -0,0 +1,118 @@
+/*
+ * 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.beans.factory.support;
+
+import java.lang.reflect.Method;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.BeanInstantiationException;
+import org.springframework.util.ReflectionUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+/**
+ * Tests for {@link SimpleInstantiationStrategy}.
+ *
+ * @author Stephane Nicoll
+ */
+class SimpleInstantiationStrategyTests {
+
+	private final DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
+
+	private final SimpleInstantiationStrategy strategy = new SimpleInstantiationStrategy();
+
+	@Test
+	void instantiateWithNoArg() {
+		RootBeanDefinition bd = new RootBeanDefinition(String.class);
+		Object simpleBean = instantiate(bd, new SampleFactory(),
+				method(SampleFactory.class, "simpleBean"));
+		assertThat(simpleBean).isEqualTo("Hello");
+	}
+
+	@Test
+	void instantiateWitArgs() {
+		RootBeanDefinition bd = new RootBeanDefinition(String.class);
+		Object simpleBean = instantiate(bd, new SampleFactory(),
+				method(SampleFactory.class, "beanWithTwoArgs"), "Test", 42);
+		assertThat(simpleBean).isEqualTo("Test42");
+	}
+
+	@Test
+	void instantiateWithNullValueReturnsNullBean() {
+		RootBeanDefinition bd = new RootBeanDefinition(String.class);
+		Object simpleBean = instantiate(bd, new SampleFactory(),
+				method(SampleFactory.class, "cloneBean"), new Object[] { null });
+		assertThat(simpleBean).isNotNull().isInstanceOf(NullBean.class);
+	}
+
+	@Test
+	void instantiateWithArgumentTypeMismatch() {
+		RootBeanDefinition bd = new RootBeanDefinition(String.class);
+		assertThatExceptionOfType(BeanInstantiationException.class).isThrownBy(() -> instantiate(
+						bd, new SampleFactory(),
+						method(SampleFactory.class, "beanWithTwoArgs"), 42, "Test"))
+				.withMessageContaining("Illegal arguments to factory method 'beanWithTwoArgs'")
+				.withMessageContaining("args: 42,Test");
+	}
+
+	@Test
+	void instantiateWithException() {
+		RootBeanDefinition bd = new RootBeanDefinition(String.class);
+		assertThatExceptionOfType(BeanInstantiationException.class).isThrownBy(() -> instantiate(
+						bd, new SampleFactory(),
+						method(SampleFactory.class, "errorBean"), "This a test message"))
+				.withMessageContaining("Factory method 'errorBean' threw exception")
+				.withMessageContaining("This a test message")
+				.havingCause().isInstanceOf(IllegalStateException.class).withMessage("This a test message");
+	}
+
+	private Object instantiate(RootBeanDefinition bd, Object factory, Method method, Object... args) {
+		return this.strategy.instantiate(bd, "simpleBean", this.beanFactory,
+				factory, method, args);
+	}
+
+	private static Method method(Class<?> target, String methodName) {
+		Method[] methods = ReflectionUtils.getUniqueDeclaredMethods(
+				target, method -> methodName.equals(method.getName()));
+		assertThat(methods).as("No unique method named " + methodName + " found of " + target.getName())
+				.hasSize(1);
+		return methods[0];
+	}
+
+
+	static class SampleFactory {
+
+		String simpleBean() {
+			return "Hello";
+		}
+
+		String beanWithTwoArgs(String first, Integer second) {
+			return first + second;
+		}
+
+		String cloneBean(String arg) {
+			return arg;
+		}
+
+		String errorBean(String msg) {
+			throw new IllegalStateException(msg);
+		}
+
+	}
+}