Add test to verify DynamicProperty Overrides Existing Properties

Closes gh-26

Author: rwinch

spring-boot-testjars/src/test/java/org/springframework/experimental/boot/test/context/DynamicPropertyOverridesTests.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2012-2023 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.experimental.boot.test.context;
+
+import example.authzserver.AuthServerMain;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.TestConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.core.env.Environment;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@SpringBootTest(classes = { AuthServerMain.class, DynamicPropertyOverridesTests.Configuration.class })
+class DynamicPropertyOverridesTests {
+
+	@Test
+	void dynamicPropertyJavadoc(@Autowired Environment environment) {
+		assertThat(environment.getProperty("shouldoverride")).isEqualTo("http://localhost:1234");
+	}
+
+	@EnableDynamicProperty
+	@TestConfiguration(proxyBeanMethods = false)
+	static class Configuration {
+
+		@Bean
+		@DynamicProperty(name = "shouldoverride", value = "'http://localhost:' + port")
+		static WebServer messageService() {
+			return new WebServer();
+		}
+
+	}
+
+}

spring-boot-testjars/src/test/resources/application.yml

@@ -0,0 +1 @@
+shouldoverride: willbereplaced