Add reactor-test if the project has a reactive dependency which is not a Spring Boot starter

Closes gh-1974

Author: mhalbritter

start-site/src/main/java/io/spring/start/site/extension/dependency/DependencyProjectGenerationConfiguration.java

@@ -65,7 +65,6 @@ AddTestStartersBuildCustomizer addTestStartersBuildCustomizer() {
 	}
 
 	@Bean
-	@ConditionalOnPlatformVersion("[3.4.0,4.0.0-RC1]")
 	public ReactorTestBuildCustomizer reactorTestBuildCustomizer(ProjectDescription description) {
 		return new ReactorTestBuildCustomizer(this.metadata, description);
 	}

start-site/src/main/java/io/spring/start/site/extension/dependency/reactor/ReactorTestBuildCustomizer.java

@@ -22,6 +22,9 @@
 import io.spring.initializr.generator.project.ProjectDescription;
 import io.spring.initializr.generator.spring.build.BuildCustomizer;
 import io.spring.initializr.generator.spring.build.BuildMetadataResolver;
+import io.spring.initializr.generator.version.Version;
+import io.spring.initializr.generator.version.VersionParser;
+import io.spring.initializr.generator.version.VersionRange;
 import io.spring.initializr.metadata.InitializrMetadata;
 
 /**
@@ -30,22 +33,46 @@
  *
  * @author Stephane Nicoll
  * @author Madhura Bhave
+ * @author Moritz Halbritter
  */
 public class ReactorTestBuildCustomizer implements BuildCustomizer<Build> {
 
+	private static final VersionRange SPRING_BOOT_4_0_RC2_OR_LATER = VersionParser.DEFAULT.parseRange("4.0.0-RC2");
+
 	private final BuildMetadataResolver buildResolver;
 
+	private final Version bootVersion;
+
 	public ReactorTestBuildCustomizer(InitializrMetadata metadata, ProjectDescription description) {
+		this.bootVersion = description.getPlatformVersion();
 		this.buildResolver = new BuildMetadataResolver(metadata, description.getPlatformVersion());
 	}
 
 	@Override
 	public void customize(Build build) {
-		if (this.buildResolver.hasFacet(build, "reactive")) {
+		if (shouldAddReactorTestDependency(build)) {
 			build.dependencies()
 				.add("reactor-test", Dependency.withCoordinates("io.projectreactor", "reactor-test")
 					.scope(DependencyScope.TEST_COMPILE));
 		}
 	}
 
+	private boolean shouldAddReactorTestDependency(Build build) {
+		if (SPRING_BOOT_4_0_RC2_OR_LATER.match(this.bootVersion)) {
+			// Starting with Boot 4.0.0-RC2, all Spring Boot reactive starters have a
+			// dependency on io.projectreactor:reactor-test in their test starter
+			return this.buildResolver.dependencies(build)
+				.anyMatch((dependency) -> hasReactiveFacet(dependency) && !isSpringBootStarter(dependency));
+		}
+		return this.buildResolver.hasFacet(build, "reactive");
+	}
+
+	private boolean hasReactiveFacet(io.spring.initializr.metadata.Dependency dependency) {
+		return dependency.getFacets().contains("reactive");
+	}
+
+	private boolean isSpringBootStarter(io.spring.initializr.metadata.Dependency dependency) {
+		return dependency.isStarter() && dependency.getGroupId().equals("org.springframework.boot");
+	}
+
 }

start-site/src/test/java/io/spring/start/site/extension/dependency/reactor/ReactorTestBuildCustomizerTests.java

@@ -44,10 +44,22 @@ void shouldNotAddTestDependencyWithoutReactiveFacet() {
 		assertThat(mavenPom(request)).doesNotHaveDependency("io.projectreactor", "reactor-test");
 	}
 
+	@Test
+	void shouldNotAddTestDependencyForBoot4WithoutReactiveFacet() {
+		ProjectRequest request = createProjectRequest(SupportedBootVersion.V4_0, "web");
+		assertThat(mavenPom(request)).doesNotHaveDependency("io.projectreactor", "reactor-test");
+	}
+
 	@Test
 	void shouldNotAddTestDependencyForBoot4() {
 		ProjectRequest request = createProjectRequest(SupportedBootVersion.V4_0, "webflux");
 		assertThat(mavenPom(request)).doesNotHaveDependency("io.projectreactor", "reactor-test");
 	}
 
+	@Test
+	void shouldAddTestDependencyForBoot4IfNonBootStarterIsUsed() {
+		ProjectRequest request = createProjectRequest(SupportedBootVersion.V4_0, "cloud-gateway-reactive");
+		assertThat(mavenPom(request)).hasDependency("io.projectreactor", "reactor-test", null, Dependency.SCOPE_TEST);
+	}
+
 }