Ignore schema username when auto-configuring a test DB

Previously, when an embedded test database was being auto-configured
any schema username and password specified by the user would result
in a separate embedded test database being created to load the schema.
This then left the actual test database without the schema causing
test failures.

This commit updates the test database auto-configuration to set the
schema username to an empty string in a property source that's added
first to the environment's property sources. This causes any schema
username configured by the user to be ignored, preventing the creation
of a separate database for schema.sql processing.

Fixes gh-19321

Author: wilkinsona

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

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.test.autoconfigure.jdbc;
 
+import java.util.Collections;
+
 import javax.sql.DataSource;
 
 import org.apache.commons.logging.Log;
@@ -40,7 +42,9 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
+import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.Environment;
+import org.springframework.core.env.MapPropertySource;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabase;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
 import org.springframework.util.Assert;
@@ -168,6 +172,10 @@ private static class EmbeddedDataSourceFactory {
 
 		EmbeddedDataSourceFactory(Environment environment) {
 			this.environment = environment;
+			if (environment instanceof ConfigurableEnvironment) {
+				((ConfigurableEnvironment) environment).getPropertySources().addFirst(new MapPropertySource(
+						"testDatabase", Collections.singletonMap("spring.datasource.schema-username", "")));
+			}
 		}
 
 		EmbeddedDatabase getEmbeddedDatabase() {

spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/orm/jpa/DataJpaTestSchemaCredentialsIntegrationTests.java

@@ -0,0 +1,48 @@
+/*
+ * 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.
+ * 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.boot.test.autoconfigure.orm.jpa;
+
+import javax.sql.DataSource;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.TestPropertySource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for {@link DataJpaTest @DataJpaTest} with schema credentials that
+ * should be ignored to allow the auto-configured test database to be used.
+ *
+ * @author Andy Wilkinson
+ */
+@DataJpaTest
+@TestPropertySource(
+		properties = { "spring.datasource.schema-username=alice", "spring.datasource.schema-password=secret" })
+class DataJpaTestSchemaCredentialsIntegrationTests {
+
+	@Autowired
+	private DataSource dataSource;
+
+	@Test
+	void replacesDefinedDataSourceWithEmbeddedDefault() throws Exception {
+		String product = this.dataSource.getConnection().getMetaData().getDatabaseProductName();
+		assertThat(product).isEqualTo("H2");
+	}
+
+}