Honor @⁠Fallback semantics for Test Bean Overrides

Closes gh-33924

spring-test/src/test/java/org/springframework/test/context/bean/override/convention/TestBeanWithMultipleExistingBeansAndOneNonFallbackIntegrationTests.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2002-2024 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.bean.override.convention;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Fallback;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.bean.override.example.ExampleService;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Verifies that {@link TestBean @TestBean} can be used to override a bean by-type
+ * when there are multiple candidates and only one that is not a fallback.
+ *
+ * @author Sam Brannen
+ * @since 6.2.1
+ */
+@ExtendWith(SpringExtension.class)
+@DirtiesContext
+class TestBeanWithMultipleExistingBeansAndOneNonFallbackIntegrationTests {
+
+	@TestBean
+	ExampleService service;
+
+	@Autowired
+	List<ExampleService> services;
+
+
+	static ExampleService service() {
+		return () -> "overridden";
+	}
+
+
+	@Test
+	void test() {
+		assertThat(service.greeting()).isEqualTo("overridden");
+		assertThat(services).extracting(ExampleService::greeting)
+				.containsExactlyInAnyOrder("overridden", "two", "three");
+	}
+
+
+	@Configuration(proxyBeanMethods = false)
+	static class Config {
+
+		@Bean
+		ExampleService one() {
+			return () -> "one";
+		}
+
+		@Bean
+		@Fallback
+		ExampleService two() {
+			return () -> "two";
+		}
+
+		@Bean
+		@Fallback
+		ExampleService three() {
+			return () -> "three";
+		}
+	}
+
+}