Make the Equo-based steps round-trip serializable (#1950 towards #1274)

lib-extra/src/main/java/com/diffplug/spotless/extra/EquoBasedStepBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 DiffPlug
+ * Copyright 2016-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,7 +34,7 @@
 import com.diffplug.spotless.FormatterStep;
 import com.diffplug.spotless.JarState;
 import com.diffplug.spotless.Provisioner;
-import com.diffplug.spotless.ThrowingEx;
+import com.diffplug.spotless.SerializedFunction;
 
 import dev.equo.solstice.NestedJars;
 import dev.equo.solstice.p2.P2ClientCache;
@@ -48,19 +48,19 @@
 public abstract class EquoBasedStepBuilder {
 	private final String formatterName;
 	private final Provisioner mavenProvisioner;
-	private final ThrowingEx.Function<State, FormatterFunc> stateToFormatter;
+	private final SerializedFunction<State, FormatterFunc> stateToFormatter;
 	private String formatterVersion;
 	private Iterable<File> settingsFiles = new ArrayList<>();
 	private Map<String, String> p2Mirrors = Map.of();
 
 	/** @deprecated if you use this constructor you *must* call {@link #setVersion(String)} before calling {@link #build()} */
 	@Deprecated
-	public EquoBasedStepBuilder(String formatterName, Provisioner mavenProvisioner, ThrowingEx.Function<State, FormatterFunc> stateToFormatter) {
+	public EquoBasedStepBuilder(String formatterName, Provisioner mavenProvisioner, SerializedFunction<State, FormatterFunc> stateToFormatter) {
 		this(formatterName, mavenProvisioner, null, stateToFormatter);
 	}
 
 	/** Initialize valid default configuration, taking latest version */
-	public EquoBasedStepBuilder(String formatterName, Provisioner mavenProvisioner, @Nullable String defaultVersion, ThrowingEx.Function<State, FormatterFunc> stateToFormatter) {
+	public EquoBasedStepBuilder(String formatterName, Provisioner mavenProvisioner, @Nullable String defaultVersion, SerializedFunction<State, FormatterFunc> stateToFormatter) {
 		this.formatterName = formatterName;
 		this.mavenProvisioner = mavenProvisioner;
 		this.formatterVersion = defaultVersion;
@@ -83,11 +83,6 @@ public void setP2Mirrors(Collection<P2Mirror> p2Mirrors) {
 		this.p2Mirrors = p2Mirrors.stream().collect(toMap(P2Mirror::getPrefix, P2Mirror::getUrl));
 	}
 
-	/** Returns the FormatterStep (whose state will be calculated lazily). */
-	public FormatterStep build() {
-		return FormatterStep.createLazy(formatterName, this::get, stateToFormatter);
-	}
-
 	protected abstract P2Model model(String version);
 
 	protected void addPlatformRepo(P2Model model, String version) {
@@ -107,26 +102,28 @@ protected void addPlatformRepo(P2Model model, String version) {
 		}
 	}
 
-	/** Creates the state of the configuration. */
-	EquoBasedStepBuilder.State get() throws Exception {
-		P2QueryResult query;
-		try {
-			query = createModelWithMirrors().query(P2ClientCache.PREFER_OFFLINE, P2QueryCache.ALLOW);
-		} catch (Exception x) {
-			throw new IOException("Failed to load " + formatterName + ": " + x, x);
-		}
-		var classpath = new ArrayList<File>();
-		var mavenDeps = new ArrayList<String>();
-		mavenDeps.add("dev.equo.ide:solstice:1.7.4");
-		mavenDeps.add("com.diffplug.durian:durian-swt.os:4.2.0");
-		mavenDeps.addAll(query.getJarsOnMavenCentral());
-		classpath.addAll(mavenProvisioner.provisionWithTransitives(false, mavenDeps));
-		classpath.addAll(query.getJarsNotOnMavenCentral());
-		for (var nested : NestedJars.inFiles(query.getJarsNotOnMavenCentral()).extractAllNestedJars()) {
-			classpath.add(nested.getValue());
-		}
-		var jarState = JarState.preserveOrder(classpath);
-		return new State(formatterVersion, jarState, FileSignature.signAsList(settingsFiles));
+	/** Returns the FormatterStep (whose state will be calculated lazily). */
+	public FormatterStep build() {
+		var roundtrippableState = new EquoStep(formatterVersion, FileSignature.promise(settingsFiles), JarState.promise(() -> {
+			P2QueryResult query;
+			try {
+				query = createModelWithMirrors().query(P2ClientCache.PREFER_OFFLINE, P2QueryCache.ALLOW);
+			} catch (Exception x) {
+				throw new IOException("Failed to load " + formatterName + ": " + x, x);
+			}
+			var classpath = new ArrayList<File>();
+			var mavenDeps = new ArrayList<String>();
+			mavenDeps.add("dev.equo.ide:solstice:1.7.5");
+			mavenDeps.add("com.diffplug.durian:durian-swt.os:4.2.0");
+			mavenDeps.addAll(query.getJarsOnMavenCentral());
+			classpath.addAll(mavenProvisioner.provisionWithTransitives(false, mavenDeps));
+			classpath.addAll(query.getJarsNotOnMavenCentral());
+			for (var nested : NestedJars.inFiles(query.getJarsNotOnMavenCentral()).extractAllNestedJars()) {
+				classpath.add(nested.getValue());
+			}
+			return JarState.preserveOrder(classpath);
+		}));
+		return FormatterStep.create(formatterName, roundtrippableState, EquoStep::state, stateToFormatter);
 	}
 
 	private P2Model createModelWithMirrors() {
@@ -152,12 +149,29 @@ private P2Model createModelWithMirrors() {
 		return model;
 	}
 
+	static class EquoStep implements Serializable {
+		private static final long serialVersionUID = 1;
+		private final String semanticVersion;
+		private final FileSignature.Promised settingsPromise;
+		private final JarState.Promised jarPromise;
+
+		EquoStep(String semanticVersion, FileSignature.Promised settingsPromise, JarState.Promised jarPromise) {
+			this.semanticVersion = semanticVersion;
+			this.settingsPromise = settingsPromise;
+			this.jarPromise = jarPromise;
+		}
+
+		private State state() {
+			return new State(semanticVersion, jarPromise.get(), settingsPromise.get());
+		}
+	}
+
 	/**
 	 * State of Eclipse configuration items, providing functionality to derived information
 	 * based on the state.
 	 */
 	public static class State implements Serializable {
-		private static final long serialVersionUID = 584400372246020995L;
+		private static final long serialVersionUID = 1;
 		final String semanticVersion;
 		final JarState jarState;
 		final FileSignature settingsFiles;

lib-extra/src/test/java/com/diffplug/spotless/extra/cpp/EclipseCdtFormatterStepTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 DiffPlug
+ * Copyright 2016-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,17 +24,16 @@
 import com.diffplug.spotless.extra.eclipse.EquoResourceHarness;
 
 class EclipseCdtFormatterStepTest extends EquoResourceHarness {
-	private final static String INPUT = "#include <a.h>;\nint main(int argc,   \nchar *argv[]) {}";
-	private final static String EXPECTED = "#include <a.h>;\nint main(int argc, char *argv[]) {\n}\n";
-
 	public EclipseCdtFormatterStepTest() {
-		super(EclipseCdtFormatterStep.createBuilder(TestProvisioner.mavenCentral()), INPUT, EXPECTED);
+		super(EclipseCdtFormatterStep.createBuilder(TestProvisioner.mavenCentral()));
 	}
 
 	@ParameterizedTest
 	@MethodSource
 	void formatWithVersion(String version) throws Exception {
-		assertFormatted(version);
+		harnessFor(version).test("main.c",
+				"#include <a.h>;\nint main(int argc,   \nchar *argv[]) {}",
+				"#include <a.h>;\nint main(int argc, char *argv[]) {\n}\n");
 	}
 
 	private static Stream<String> formatWithVersion() {

lib-extra/src/test/java/com/diffplug/spotless/extra/eclipse/EquoResourceHarness.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 DiffPlug
+ * Copyright 2016-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,14 +15,12 @@
  */
 package com.diffplug.spotless.extra.eclipse;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
 import java.io.File;
 import java.util.Arrays;
 
 import com.diffplug.spotless.FormatterStep;
-import com.diffplug.spotless.LineEnding;
 import com.diffplug.spotless.ResourceHarness;
+import com.diffplug.spotless.StepHarnessWithFile;
 import com.diffplug.spotless.extra.EquoBasedStepBuilder;
 
 /**
@@ -43,57 +41,19 @@
  */
 public class EquoResourceHarness extends ResourceHarness {
 	private final EquoBasedStepBuilder stepBuilder;
-	private final String fileName;
-	private final String input;
-	private final String expected;
-
-	/**
-	 * Create harness to be used for several versions of the formatter step
-	 * @param builder Eclipse Formatter step builder
-	 * @param unformatted Simple unformatted input
-	 * @param formatted Expected formatted output
-	 */
-	public EquoResourceHarness(EquoBasedStepBuilder builder, String unformatted, String formatted) {
-		this(builder, "someSourceFile", unformatted, formatted);
-	}
 
 	/**
 	 * Create harness to be used for several versions of the formatter step
 	 * @param builder Eclipse Formatter step builder
-	 * @param sourceFileName File name of the source file
-	 * @param unformatted Simple unformatted input
-	 * @param formatted Expected formatted output
 	 */
-	public EquoResourceHarness(EquoBasedStepBuilder builder, String sourceFileName, String unformatted, String formatted) {
+	public EquoResourceHarness(EquoBasedStepBuilder builder) {
 		stepBuilder = builder;
-		fileName = sourceFileName;
-		input = unformatted;
-		expected = formatted;
 	}
 
-	/**
-	 * Assert that formatting input results in expected output
-	 * @param formatterVersion Formatter version
-	 * @param settingsFiles Formatter settings
-	 * @return Formatted string
-	 */
-	protected String assertFormatted(String formatterVersion, File... settingsFiles) throws Exception {
-		String output = format(formatterVersion, settingsFiles);
-		assertThat(output).isEqualTo(expected);
-		return output;
-	}
-
-	/**
-	 * Formatting input results and returns output
-	 * @param formatterVersion Formatter version
-	 * @param settingsFiles Formatter settings
-	 * @return Formatted string
-	 */
-	protected String format(String formatterVersion, File... settingsFiles) throws Exception {
-		File inputFile = setFile(fileName).toContent(input);
+	protected StepHarnessWithFile harnessFor(String formatterVersion, File... settingsFiles) throws Exception {
 		stepBuilder.setVersion(formatterVersion);
 		stepBuilder.setPreferences(Arrays.asList(settingsFiles));
 		FormatterStep step = stepBuilder.build();
-		return LineEnding.toUnix(step.format(input, inputFile));
+		return StepHarnessWithFile.forStep(this, step);
 	}
 }

lib-extra/src/test/java/com/diffplug/spotless/extra/groovy/GrEclipseFormatterStepTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 DiffPlug
+ * Copyright 2016-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,13 +28,14 @@ public class GrEclipseFormatterStepTest extends EquoResourceHarness {
 	private final static String EXPECTED = "class F{\n\tdef m(){}\n}";
 
 	public GrEclipseFormatterStepTest() {
-		super(GrEclipseFormatterStep.createBuilder(TestProvisioner.mavenCentral()), INPUT, EXPECTED);
+		super(GrEclipseFormatterStep.createBuilder(TestProvisioner.mavenCentral()));
 	}
 
 	@ParameterizedTest
 	@MethodSource
 	void formatWithVersion(String version) throws Exception {
-		assertFormatted(version);
+		harnessFor(version).test("test.groovy",
+				"class F{ def m(){} }", "class F{\n\tdef m(){}\n}");
 	}
 
 	private static Stream<String> formatWithVersion() {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 DiffPlug
+ * Copyright 2016-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,7 +15,6 @@
  */
 package com.diffplug.spotless.extra.java;
 
-import java.io.File;
 import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Nested;
@@ -28,21 +27,20 @@
 import com.diffplug.spotless.extra.eclipse.EquoResourceHarness;
 
 class EclipseJdtFormatterStepTest extends EquoResourceHarness {
-	private final static String INPUT = "package p; class C{}";
-	private final static String EXPECTED = "package p;\nclass C {\n}";
-
 	private static EquoBasedStepBuilder createBuilder() {
 		return EclipseJdtFormatterStep.createBuilder(TestProvisioner.mavenCentral());
 	}
 
 	public EclipseJdtFormatterStepTest() {
-		super(createBuilder(), INPUT, EXPECTED);
+		super(createBuilder());
 	}
 
 	@ParameterizedTest
 	@MethodSource
 	void formatWithVersion(String version) throws Exception {
-		assertFormatted(version);
+		harnessFor(version).test("test.java",
+				"package p; class C{}",
+				"package p;\nclass C {\n}");
 	}
 
 	private static Stream<String> formatWithVersion() {
@@ -53,13 +51,13 @@ private static Stream<String> formatWithVersion() {
 	@Nested
 	class NewFormatInterface extends EquoResourceHarness {
 		public NewFormatInterface() {
-			super(createBuilder(), "module-info.java", getTestResource("java/eclipse/ModuleInfoUnformatted.test"), getTestResource("java/eclipse/ModuleInfoFormatted.test"));
+			super(createBuilder());
 		}
 
 		@Test
 		void formatModuleInfo() throws Exception {
-			File settingsFile = createTestFile("java/eclipse/ModuleInfo.prefs");
-			assertFormatted("4.11", settingsFile);
+			harnessFor("4.11", createTestFile("java/eclipse/ModuleInfo.prefs"))
+					.testResource("module-info.java", "java/eclipse/ModuleInfoUnformatted.test", "java/eclipse/ModuleInfoFormatted.test");
 		}
 	}
 }

lib/src/main/java/com/diffplug/spotless/FileSignature.java

@@ -121,6 +121,10 @@ public Promised asPromise() {
 		return new Promised(files, this);
 	}
 
+	public static Promised promise(Iterable<File> files) {
+		return new Promised(MoreIterables.toNullHostileList(files), null);
+	}
+
 	/** Returns all of the files in this signature, throwing an exception if there are more or less than 1 file. */
 	public Collection<File> files() {
 		return Collections.unmodifiableList(files);

testlib/src/main/java/com/diffplug/spotless/StepHarnessBase.java

@@ -43,6 +43,8 @@ protected StepHarnessBase(Formatter formatter) {
 				supportsRoundTrip = true;
 			} else if (onlyStepName.equals("diktat")) {
 				supportsRoundTrip = true;
+			} else if (onlyStepName.equals("eclipse jdt formatter") || onlyStepName.equals("eclipse cdt formatter") || onlyStepName.equals("eclipse groovy formatter")) {
+				supportsRoundTrip = true;
 			}
 		}
 	}