Verify our assumptions about equality / hashCode / serialization for …

…`EclipseJdtFormatterStep` (#2193)

lib-extra/src/test/java/com/diffplug/spotless/extra/java/EclipseJdtEqualityTest.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2024 DiffPlug
+ *
+ * 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 com.diffplug.spotless.extra.java;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import java.util.List;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.ResourceHarness;
+import com.diffplug.spotless.TestProvisioner;
+import com.diffplug.spotless.ThrowingEx;
+
+public class EclipseJdtEqualityTest extends ResourceHarness {
+	@Test
+	public void test() throws Exception {
+		var settings1 = setFile("subfolder1/formatter.xml").toResource("java/eclipse/formatter.xml");
+		var settings2 = setFile("subfolder2/formatter.xml").toResource("java/eclipse/formatter.xml");
+		var step1 = withSettingsFile(settings1);
+		var step2 = withSettingsFile(settings2);
+
+		Assertions.assertTrue(step1.equals(step2));
+		Assertions.assertTrue(step1.hashCode() == step2.hashCode());
+
+		var serialized1 = toBytes(step1);
+		var serialized2 = toBytes(step2);
+		Assertions.assertFalse(serialized1.equals(serialized2));
+	}
+
+	private static FormatterStep withSettingsFile(File settingsFile) {
+		var builder = EclipseJdtFormatterStep.createBuilder(TestProvisioner.mavenCentral());
+		builder.setPreferences(List.of(settingsFile));
+		return builder.build();
+	}
+
+	private static byte[] toBytes(Serializable obj) {
+		ByteArrayOutputStream byteOutput = new ByteArrayOutputStream();
+		try (ObjectOutputStream objectOutput = new ObjectOutputStream(byteOutput)) {
+			objectOutput.writeObject(obj);
+		} catch (IOException e) {
+			throw ThrowingEx.asRuntime(e);
+		}
+		return byteOutput.toByteArray();
+	}
+}