Stop using Constants utility in LazyConnectionDataSourceProxy

See gh-30851

spring-jdbc/src/test/java/org/springframework/jdbc/datasource/LazyConnectionDataSourceProxyTests.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2002-2023 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.jdbc.datasource;
+
+import java.lang.reflect.Field;
+import java.sql.Connection;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.util.ReflectionUtils;
+
+import static java.sql.Connection.TRANSACTION_NONE;
+import static java.sql.Connection.TRANSACTION_READ_COMMITTED;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
+/**
+ * Tests for {@link LazyConnectionDataSourceProxy}.
+ *
+ * @author Sam Brannen
+ * @since 6.1
+ */
+class LazyConnectionDataSourceProxyTests {
+
+	private final LazyConnectionDataSourceProxy proxy = new LazyConnectionDataSourceProxy();
+
+
+	@Test
+	void setDefaultTransactionIsolationNameToUnsupportedValues() {
+		assertThatIllegalArgumentException().isThrownBy(() -> proxy.setDefaultTransactionIsolationName(null));
+		assertThatIllegalArgumentException().isThrownBy(() -> proxy.setDefaultTransactionIsolationName("   "));
+		assertThatIllegalArgumentException().isThrownBy(() -> proxy.setDefaultTransactionIsolationName("bogus"));
+	}
+
+	/**
+	 * Verify that the internal 'constants' map is properly configured for all
+	 * TRANSACTION_ constants defined in {@link java.sql.Connection}.
+	 */
+	@Test
+	void setDefaultTransactionIsolationNameToAllSupportedValues() {
+		Set<Integer> uniqueValues = new HashSet<>();
+		streamIsolationConstants()
+				.forEach(name -> {
+					if ("TRANSACTION_NONE".equals(name)) {
+						assertThatIllegalArgumentException().isThrownBy(() -> proxy.setDefaultTransactionIsolationName(name));
+					}
+					else {
+						proxy.setDefaultTransactionIsolationName(name);
+						Integer defaultTransactionIsolation = proxy.defaultTransactionIsolation();
+						Integer expected = LazyConnectionDataSourceProxy.constants.get(name);
+						assertThat(defaultTransactionIsolation).isEqualTo(expected);
+						uniqueValues.add(defaultTransactionIsolation);
+					}
+				});
+		assertThat(uniqueValues).containsExactlyInAnyOrderElementsOf(LazyConnectionDataSourceProxy.constants.values());
+	}
+
+	@Test
+	void setDefaultTransactionIsolation() {
+		// unsupported values are not checked:
+		proxy.setDefaultTransactionIsolation(-999);
+		assertThat(proxy.defaultTransactionIsolation()).isEqualTo(-999);
+
+		// TRANSACTION_NONE should not be supported, but we currently do not check that.
+		proxy.setDefaultTransactionIsolation(TRANSACTION_NONE);
+		assertThat(proxy.defaultTransactionIsolation()).isEqualTo(TRANSACTION_NONE);
+
+		proxy.setDefaultTransactionIsolation(TRANSACTION_READ_COMMITTED);
+		assertThat(proxy.defaultTransactionIsolation()).isEqualTo(TRANSACTION_READ_COMMITTED);
+	}
+
+
+	private static Stream<String> streamIsolationConstants() {
+		return Arrays.stream(Connection.class.getFields())
+				.filter(ReflectionUtils::isPublicStaticFinal)
+				.map(Field::getName)
+				.filter(name -> name.startsWith("TRANSACTION_"));
+	}
+
+}