Fix NPE in url is null and no embedded database is available

Closes gh-10626

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

@@ -106,7 +106,7 @@ public enum EmbeddedDatabaseConnection {
 	 */
 	public String getUrl(String databaseName) {
 		Assert.hasText(databaseName, "DatabaseName must not be null.");
-		return String.format(this.url, databaseName);
+		return this.url != null ? String.format(this.url, databaseName) : null;
 	}
 
 	/**

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

@@ -16,8 +16,6 @@
 
 package org.springframework.boot.autoconfigure.jdbc;
 
-import java.net.URL;
-import java.net.URLClassLoader;
 import java.sql.Connection;
 import java.sql.Driver;
 import java.sql.DriverPropertyInfo;
@@ -323,26 +321,4 @@ public class DataSourceAutoConfigurationTests {
 
 	}
 
-	private static final class HidePackagesClassLoader extends URLClassLoader {
-
-		private final String[] hiddenPackages;
-
-		private HidePackagesClassLoader(String... hiddenPackages) {
-			super(new URL[0], DataSourceAutoConfigurationTests.class.getClassLoader());
-			this.hiddenPackages = hiddenPackages;
-		}
-
-		@Override
-		protected Class<?> loadClass(String name, boolean resolve)
-				throws ClassNotFoundException {
-			for (String hiddenPackage : this.hiddenPackages) {
-				if (name.startsWith(hiddenPackage)) {
-					throw new ClassNotFoundException();
-				}
-			}
-			return super.loadClass(name, resolve);
-		}
-
-	}
-
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -16,7 +16,9 @@
 
 package org.springframework.boot.autoconfigure.jdbc;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -29,6 +31,9 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 public class DataSourcePropertiesTests {
 
+	@Rule
+	public final ExpectedException thrown = ExpectedException.none();
+
 	@Test
 	public void determineDriver() {
 		DataSourceProperties properties = new DataSourceProperties();
@@ -57,6 +62,17 @@ public class DataSourcePropertiesTests {
 				.isEqualTo(EmbeddedDatabaseConnection.H2.getUrl());
 	}
 
+	@Test
+	public void determineUrlWithNoEmbeddedSupport() throws Exception {
+		DataSourceProperties properties = new DataSourceProperties();
+		properties.setBeanClassLoader(new HidePackagesClassLoader("org.h2",
+				"org.apache.derby", "org.hsqldb"));
+		properties.afterPropertiesSet();
+		this.thrown.expect(DataSourceProperties.DataSourceBeanCreationException.class);
+		this.thrown.expectMessage("Cannot determine embedded database url");
+		properties.determineUrl();
+	}
+
 	@Test
 	public void determineUrlWithExplicitConfig() throws Exception {
 		DataSourceProperties properties = new DataSourceProperties();

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

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2012-2017 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
+ *
+ *      http://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.boot.autoconfigure.jdbc;
+
+import java.net.URL;
+import java.net.URLClassLoader;
+
+/**
+ * Test {@link URLClassLoader} that hides configurable packages. No class in one of those
+ * packages or sub-packages are visible.
+ *
+ * @author Stephane Nicoll
+ */
+final class HidePackagesClassLoader extends URLClassLoader {
+
+	private final String[] hiddenPackages;
+
+	HidePackagesClassLoader(String... hiddenPackages) {
+		super(new URL[0], DataSourceAutoConfigurationTests.class.getClassLoader());
+		this.hiddenPackages = hiddenPackages;
+	}
+
+	@Override
+	protected Class<?> loadClass(String name, boolean resolve)
+			throws ClassNotFoundException {
+		for (String hiddenPackage : this.hiddenPackages) {
+			if (name.startsWith(hiddenPackage)) {
+				throw new ClassNotFoundException();
+			}
+		}
+		return super.loadClass(name, resolve);
+	}
+
+}