Allow to customize how build writers sort dependencies

Closes gh-1098

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/gradle/GradleBuildWriter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * 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.
@@ -142,6 +142,14 @@ public abstract class GradleBuildWriter {
 		return (scope) -> Arrays.asList(validScopes).contains(scope);
 	}
 
+	/**
+	 * Return the {@link Comparator} to use to sort dependencies.
+	 * @return a dependency comparator
+	 */
+	protected Comparator<Dependency> getDependencyComparator() {
+		return DependencyComparator.INSTANCE;
+	}
+
 	protected abstract void writeDependency(IndentingWriter writer, Dependency dependency);
 
 	protected String configurationForDependency(Dependency dependency) {
@@ -242,9 +250,9 @@ public abstract class GradleBuildWriter {
 
 	protected abstract void writeProperty(IndentingWriter writer, String name, String value);
 
-	private static Collection<Dependency> filterDependencies(DependencyContainer dependencies,
+	private Collection<Dependency> filterDependencies(DependencyContainer dependencies,
 			Predicate<DependencyScope> filter) {
-		return dependencies.items().filter((dep) -> filter.test(dep.getScope())).sorted(DependencyComparator.INSTANCE)
+		return dependencies.items().filter((dep) -> filter.test(dep.getScope())).sorted(getDependencyComparator())
 				.collect(Collectors.toList());
 	}
 

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/maven/MavenBuildWriter.java

@@ -83,6 +83,14 @@ public class MavenBuildWriter {
 		});
 	}
 
+	/**
+	 * Return the {@link Comparator} to use to sort dependencies.
+	 * @return a dependency comparator
+	 */
+	protected Comparator<Dependency> getDependencyComparator() {
+		return DependencyComparator.INSTANCE;
+	}
+
 	private void writeProject(IndentingWriter writer, Runnable whenWritten) {
 		writer.println("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
 		writer.println(
@@ -214,7 +222,7 @@ public class MavenBuildWriter {
 	private Collection<Dependency> writeDependencies(IndentingWriter writer, DependencyContainer dependencies,
 			Predicate<DependencyScope> filter) {
 		Collection<Dependency> candidates = dependencies.items().filter((dep) -> filter.test(dep.getScope()))
-				.sorted(DependencyComparator.INSTANCE).collect(Collectors.toList());
+				.sorted(getDependencyComparator()).collect(Collectors.toList());
 		writeCollection(writer, candidates, this::writeDependency);
 		return candidates;
 	}

initializr-generator/src/test/java/io/spring/initializr/generator/buildsystem/gradle/GroovyDslGradleBuildWriterTests.java

@@ -18,6 +18,7 @@ package io.spring.initializr.generator.buildsystem.gradle;
 
 import java.io.StringWriter;
 import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 
 import io.spring.initializr.generator.buildsystem.BillOfMaterials;
@@ -415,6 +416,41 @@ class GroovyDslGradleBuildWriterTests {
 				"}");
 	}
 
+	@Test
+	void gradleBuildWithOrderedDependencies() {
+		GradleBuild build = new GradleBuild();
+		build.dependencies().add("beta", Dependency.withCoordinates("com.example", "beta"));
+		build.dependencies().add("alpha", Dependency.withCoordinates("com.example", "alpha"));
+		build.dependencies().add("web",
+				Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter-web"));
+		build.dependencies().add("root", Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter"));
+		List<String> lines = generateBuild(build);
+		assertThat(lines).containsSequence("    implementation 'org.springframework.boot:spring-boot-starter'",
+				"    implementation 'org.springframework.boot:spring-boot-starter-web'",
+				"    implementation 'com.example:alpha'", "    implementation 'com.example:beta'");
+	}
+
+	@Test
+	void gradleBuildWithOrderedDependenciesAndCustomComparator() {
+		GradleBuild build = new GradleBuild();
+		build.dependencies().add("beta", Dependency.withCoordinates("com.example", "beta"));
+		build.dependencies().add("alpha", Dependency.withCoordinates("com.example", "alpha"));
+		build.dependencies().add("web",
+				Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter-web"));
+		build.dependencies().add("root", Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter"));
+		GroovyDslGradleBuildWriter writer = new GroovyDslGradleBuildWriter() {
+			@Override
+			protected Comparator<Dependency> getDependencyComparator() {
+				return Comparator.comparing(Dependency::getArtifactId);
+			}
+		};
+		List<String> lines = generateBuild(writer, build);
+		assertThat(lines).containsSequence("    implementation 'com.example:alpha'",
+				"    implementation 'com.example:beta'",
+				"    implementation 'org.springframework.boot:spring-boot-starter'",
+				"    implementation 'org.springframework.boot:spring-boot-starter-web'");
+	}
+
 	@Test
 	void gradleBuildWithBom() {
 		GradleBuild build = new GradleBuild();
@@ -447,7 +483,10 @@ class GroovyDslGradleBuildWriterTests {
 	}
 
 	private List<String> generateBuild(GradleBuild build) {
-		GradleBuildWriter writer = new GroovyDslGradleBuildWriter();
+		return generateBuild(new GroovyDslGradleBuildWriter(), build);
+	}
+
+	private List<String> generateBuild(GroovyDslGradleBuildWriter writer, GradleBuild build) {
 		StringWriter out = new StringWriter();
 		writer.writeTo(new IndentingWriter(out), build);
 		String[] lines = out.toString().split("\\r?\\n");

initializr-generator/src/test/java/io/spring/initializr/generator/buildsystem/gradle/KotlinDslGradleBuildWriterTests.java

@@ -18,6 +18,7 @@ package io.spring.initializr.generator.buildsystem.gradle;
 
 import java.io.StringWriter;
 import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 
 import io.spring.initializr.generator.buildsystem.BillOfMaterials;
@@ -424,6 +425,41 @@ class KotlinDslGradleBuildWriterTests {
 				"}");
 	}
 
+	@Test
+	void gradleBuildWithOrderedDependencies() {
+		GradleBuild build = new GradleBuild();
+		build.dependencies().add("beta", Dependency.withCoordinates("com.example", "beta"));
+		build.dependencies().add("alpha", Dependency.withCoordinates("com.example", "alpha"));
+		build.dependencies().add("web",
+				Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter-web"));
+		build.dependencies().add("root", Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter"));
+		List<String> lines = generateBuild(build);
+		assertThat(lines).containsSequence("    implementation(\"org.springframework.boot:spring-boot-starter\")",
+				"    implementation(\"org.springframework.boot:spring-boot-starter-web\")",
+				"    implementation(\"com.example:alpha\")", "    implementation(\"com.example:beta\")");
+	}
+
+	@Test
+	void gradleBuildWithOrderedDependenciesAndCustomComparator() {
+		GradleBuild build = new GradleBuild();
+		build.dependencies().add("beta", Dependency.withCoordinates("com.example", "beta"));
+		build.dependencies().add("alpha", Dependency.withCoordinates("com.example", "alpha"));
+		build.dependencies().add("web",
+				Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter-web"));
+		build.dependencies().add("root", Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter"));
+		KotlinDslGradleBuildWriter writer = new KotlinDslGradleBuildWriter() {
+			@Override
+			protected Comparator<Dependency> getDependencyComparator() {
+				return Comparator.comparing(Dependency::getArtifactId);
+			}
+		};
+		List<String> lines = generateBuild(writer, build);
+		assertThat(lines).containsSequence("    implementation(\"com.example:alpha\")",
+				"    implementation(\"com.example:beta\")",
+				"    implementation(\"org.springframework.boot:spring-boot-starter\")",
+				"    implementation(\"org.springframework.boot:spring-boot-starter-web\")");
+	}
+
 	@Test
 	void gradleBuildWithBom() {
 		GradleBuild build = new GradleBuild();
@@ -456,7 +492,10 @@ class KotlinDslGradleBuildWriterTests {
 	}
 
 	private List<String> generateBuild(GradleBuild build) {
-		GradleBuildWriter writer = new KotlinDslGradleBuildWriter();
+		return generateBuild(new KotlinDslGradleBuildWriter(), build);
+	}
+
+	private List<String> generateBuild(KotlinDslGradleBuildWriter writer, GradleBuild build) {
 		StringWriter out = new StringWriter();
 		writer.writeTo(new IndentingWriter(out), build);
 		String[] lines = out.toString().split("\\r?\\n");

initializr-generator/src/test/java/io/spring/initializr/generator/buildsystem/maven/MavenBuildWriterTests.java

@@ -17,6 +17,7 @@
 package io.spring.initializr.generator.buildsystem.maven;
 
 import java.io.StringWriter;
+import java.util.Comparator;
 import java.util.function.Consumer;
 
 import io.spring.initializr.generator.buildsystem.BillOfMaterials;
@@ -420,6 +421,39 @@ class MavenBuildWriterTests {
 		});
 	}
 
+	@Test
+	void pomWithOrderedDependencies() {
+		MavenBuild build = new MavenBuild();
+		build.dependencies().add("beta", Dependency.withCoordinates("com.example", "beta"));
+		build.dependencies().add("alpha", Dependency.withCoordinates("com.example", "alpha"));
+		build.dependencies().add("web",
+				Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter-web"));
+		build.dependencies().add("root", Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter"));
+		String pom = writePom(new MavenBuildWriter(), build);
+		assertThat(pom).containsSubsequence("<artifactId>spring-boot-starter</artifactId>",
+				"<artifactId>spring-boot-starter-web</artifactId>", "<artifactId>alpha</artifactId>",
+				"<artifactId>beta</artifactId>");
+	}
+
+	@Test
+	void pomWithOrderedDependenciesAndCustomComparator() {
+		MavenBuild build = new MavenBuild();
+		build.dependencies().add("beta", Dependency.withCoordinates("com.example", "beta"));
+		build.dependencies().add("alpha", Dependency.withCoordinates("com.example", "alpha"));
+		build.dependencies().add("web",
+				Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter-web"));
+		build.dependencies().add("root", Dependency.withCoordinates("org.springframework.boot", "spring-boot-starter"));
+		MavenBuildWriter writer = new MavenBuildWriter() {
+			@Override
+			protected Comparator<Dependency> getDependencyComparator() {
+				return Comparator.comparing(Dependency::getArtifactId);
+			}
+		};
+		String pom = writePom(writer, build);
+		assertThat(pom).containsSubsequence("<artifactId>alpha</artifactId>", "<artifactId>beta</artifactId>",
+				"<artifactId>spring-boot-starter</artifactId>", "<artifactId>spring-boot-starter-web</artifactId>");
+	}
+
 	@Test
 	void pomWithBom() {
 		MavenBuild build = new MavenBuild();
@@ -822,17 +856,16 @@ class MavenBuildWriterTests {
 		MavenBuild build = new MavenBuild();
 		build.settings().coordinates("com.example.demo", "demo").name("<demo project>")
 				.description("A \"demo\" project for 'developers' & 'testers'");
-		String pom = writePom(build);
+		String pom = writePom(new MavenBuildWriter(), build);
 		assertThat(pom).contains("<name>&lt;demo project&gt;</name>").contains(
 				"<description>A &quot;demo&quot; project for &apos;developers&apos; &amp; &apos;testers&apos;</description>");
 	}
 
 	private void generatePom(MavenBuild mavenBuild, Consumer<NodeAssert> consumer) {
-		consumer.accept(new NodeAssert(writePom(mavenBuild)));
+		consumer.accept(new NodeAssert(writePom(new MavenBuildWriter(), mavenBuild)));
 	}
 
-	private String writePom(MavenBuild mavenBuild) {
+	private String writePom(MavenBuildWriter writer, MavenBuild mavenBuild) {
-		MavenBuildWriter writer = new MavenBuildWriter();
 		StringWriter out = new StringWriter();
 		writer.writeTo(new IndentingWriter(out), mavenBuild);
 		return out.toString();