Default spring.datasource.generate-unique-name to true

This change ensures that each test in a test suite that shares an
application context gets a unique embedded database, to prevent
inconsistent embedded database state between tests.

Closes gh-16747

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceProperties.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -44,6 +44,7 @@ import org.springframework.util.StringUtils;
  * @author Stephane Nicoll
  * @author Benedikt Ritter
  * @author Eddú Meléndez
+ * @author Scott Frederick
  * @since 1.1.0
  */
 @ConfigurationProperties(prefix = "spring.datasource")
@@ -59,7 +60,7 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	/**
 	 * Whether to generate a random datasource name.
 	 */
-	private boolean generateUniqueName;
+	private boolean generateUniqueName = true;
 
 	/**
 	 * Fully qualified name of the connection pool implementation to use. By default, it

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/DataSourcePropertiesTests.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -30,6 +30,7 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  * @author Maciej Walkowiak
  * @author Stephane Nicoll
  * @author Eddú Meléndez
+ * @author Scott Frederick
  */
 class DataSourcePropertiesTests {
 
@@ -51,8 +52,9 @@ class DataSourcePropertiesTests {
 	}
 
 	@Test
-	void determineUrl() throws Exception {
+	void determineUrlWithoutGenerateUniqueName() throws Exception {
 		DataSourceProperties properties = new DataSourceProperties();
+		properties.setGenerateUniqueName(false);
 		properties.afterPropertiesSet();
 		assertThat(properties.getUrl()).isNull();
 		assertThat(properties.determineUrl()).isEqualTo(EmbeddedDatabaseConnection.H2.getUrl("testdb"));
@@ -79,7 +81,6 @@ class DataSourcePropertiesTests {
 	@Test
 	void determineUrlWithGenerateUniqueName() throws Exception {
 		DataSourceProperties properties = new DataSourceProperties();
-		properties.setGenerateUniqueName(true);
 		properties.afterPropertiesSet();
 		assertThat(properties.determineUrl()).isEqualTo(properties.determineUrl());