Added DriverClassNameProvider used for providing jdbc driver class based on jdbc url

Uses known databases from org.flywaydb.core.internal.util.jdbc.DriverDataSource

Fixes gh-824, fixes gh-809

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

@@ -95,6 +95,8 @@ public class DataSourceAutoConfigurationTests {
 
 	@Test(expected = BeanCreationException.class)
 	public void testBadUrl() throws Exception {
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.datasource.url:jdbc:not-going-to-work");
 		EmbeddedDatabaseConnection.override = EmbeddedDatabaseConnection.NONE;
 		this.context.register(DataSourceAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class);
@@ -104,6 +106,9 @@ public class DataSourceAutoConfigurationTests {
 
 	@Test(expected = BeanCreationException.class)
 	public void testBadDriverClass() throws Exception {
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.datasource.driverClassName:org.none.jdbcDriver",
+				"spring.datasource.url:jdbc:hsqldb:mem:testdb");
 		EmbeddedDatabaseConnection.override = EmbeddedDatabaseConnection.NONE;
 		this.context.register(DataSourceAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class);

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

@@ -0,0 +1,31 @@
+package org.springframework.boot.autoconfigure.jdbc;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Tests for {@link DataSourceProperties}.
+ *
+ * @author Maciej Walkowiak
+ */
+public class DataSourcePropertiesTests {
+
+	@Test
+	public void correctDriverClassNameFromJdbcUrlWhenDriverClassNameNotDefined() {
+		DataSourceProperties configuration = new DataSourceProperties();
+		configuration.setUrl("jdbc:mysql://mydb");
+		String driverClassName = configuration.getDriverClassName();
+		assertEquals(driverClassName, "com.mysql.jdbc.Driver");
+	}
+
+	@Test
+	public void driverClassNameFromDriverClassNamePropertyWhenDefined() {
+		DataSourceProperties configuration = new DataSourceProperties();
+		configuration.setUrl("jdbc:mysql://mydb");
+		configuration.setDriverClassName("my.driver.ClassName");
+		String driverClassName = configuration.getDriverClassName();
+		assertEquals(driverClassName, "my.driver.ClassName");
+	}
+
+}

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

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2012-2014 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 org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+/**
+ * Tests for {@link DriverClassNameProvider}.
+ *
+ * @author Maciej Walkowiak
+ */
+public class DriverClassNameProviderTest {
+    private DriverClassNameProvider driverClassNameProvider = new DriverClassNameProvider();
+
+    @Test
+    public void testGettingClassNameForKnownDatabase() {
+        String driverClassName = driverClassNameProvider.getDriverClassName("jdbc:postgresql://hostname/dbname");
+
+        assertEquals("org.postgresql.Driver", driverClassName);
+    }
+
+    @Test
+    public void testReturnsNullForUnknownDatabase() {
+        String driverClassName = driverClassNameProvider.getDriverClassName("jdbc:unknowndb://hostname/dbname");
+
+        assertNull(driverClassName);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testFailureOnNullJdbcUrl() {
+        driverClassNameProvider.getDriverClassName(null);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testFailureOnMalformedJdbcUrl() {
+        driverClassNameProvider.getDriverClassName("malformed:url");
+    }
+}