Use a strategy for Kotlin version resolution

Closes gh-926

initializr-generator-spring/pom.xml

@@ -28,6 +28,11 @@
 			<artifactId>jmustache</artifactId>
 		</dependency>
 
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-autoconfigure</artifactId>
+		</dependency>
+
 		<dependency>
 			<groupId>io.spring.initializr</groupId>
 			<artifactId>initializr-generator</artifactId>

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/autoconfigure/GeneratorSpringAutoConfiguration.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.spring.autoconfigure;
+
+import io.spring.initializr.generator.spring.code.kotlin.InitializrMetadataKotlinVersionResolver;
+import io.spring.initializr.generator.spring.code.kotlin.KotlinVersionResolver;
+import io.spring.initializr.metadata.InitializrMetadataProvider;
+
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.context.annotation.Bean;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} for generation of Spring-based
+ * projects.
+ *
+ * @author Andy Wilkinson
+ */
+public class GeneratorSpringAutoConfiguration {
+
+	@Bean
+	@ConditionalOnMissingBean
+	public KotlinVersionResolver kotlinVersionResolver(InitializrMetadataProvider metadataProvider) {
+		return new InitializrMetadataKotlinVersionResolver(metadataProvider);
+	}
+
+}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/code/kotlin/InitializrMetadataKotlinVersionResolver.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.spring.code.kotlin;
+
+import io.spring.initializr.generator.project.ResolvedProjectDescription;
+import io.spring.initializr.metadata.InitializrMetadata;
+import io.spring.initializr.metadata.InitializrMetadataProvider;
+
+/**
+ * {@link KotlinVersionResolver} that resolves the version from the
+ * {@link InitializrMetadata}.
+ *
+ * @author Andy Wilkinson
+ */
+public class InitializrMetadataKotlinVersionResolver implements KotlinVersionResolver {
+
+	private final InitializrMetadataProvider metadataProvider;
+
+	public InitializrMetadataKotlinVersionResolver(InitializrMetadataProvider metadataProvider) {
+		this.metadataProvider = metadataProvider;
+	}
+
+	@Override
+	public String resolveKotlinVersion(ResolvedProjectDescription description) {
+		return this.metadataProvider.get().getConfiguration().getEnv().getKotlin()
+				.resolveKotlinVersion(description.getPlatformVersion());
+	}
+
+}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/code/kotlin/KotlinProjectGenerationConfiguration.java

@@ -32,7 +32,6 @@ import io.spring.initializr.generator.spring.code.MainSourceCodeProjectContribut
 import io.spring.initializr.generator.spring.code.TestApplicationTypeCustomizer;
 import io.spring.initializr.generator.spring.code.TestSourceCodeCustomizer;
 import io.spring.initializr.generator.spring.code.TestSourceCodeProjectContributor;
-import io.spring.initializr.metadata.InitializrMetadata;
 
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.context.annotation.Bean;
@@ -80,8 +79,8 @@ public class KotlinProjectGenerationConfiguration {
 	}
 
 	@Bean
-	public KotlinProjectSettings kotlinProjectSettings(InitializrMetadata metadata) {
-		return new MetadataKotlinProjectSettings(this.projectDescription, metadata);
+	public KotlinProjectSettings kotlinProjectSettings(KotlinVersionResolver kotlinVersionResolver) {
+		return new SimpleKotlinProjectSettings(kotlinVersionResolver.resolveKotlinVersion(this.projectDescription));
 	}
 
 }

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/code/kotlin/KotlinVersionResolver.java

@@ -17,25 +17,21 @@
 package io.spring.initializr.generator.spring.code.kotlin;
 
 import io.spring.initializr.generator.project.ResolvedProjectDescription;
-import io.spring.initializr.metadata.InitializrMetadata;
 
 /**
- * A {@link KotlinProjectSettings} that resolves the version to use from the metadata.
+ * Strategy for resolving a Kotlin version from a platform version.
  *
- * @author Stephane Nicoll
+ * @author Andy Wilkinson
  */
-public class MetadataKotlinProjectSettings implements KotlinProjectSettings {
+@FunctionalInterface
+public interface KotlinVersionResolver {
 
-	private final String version;
-
-	public MetadataKotlinProjectSettings(ResolvedProjectDescription projectDescription, InitializrMetadata metadata) {
-		this.version = metadata.getConfiguration().getEnv().getKotlin()
-				.resolveKotlinVersion(projectDescription.getPlatformVersion());
-	}
-
-	@Override
-	public String getVersion() {
-		return this.version;
-	}
+	/**
+	 * Resolves the Kotlin version to use for the generation of the project with the given
+	 * {@code description}.
+	 * @param description the description of the project being generated
+	 * @return the corresponding Kotlin version
+	 */
+	String resolveKotlinVersion(ResolvedProjectDescription description);
 
 }

initializr-generator-spring/src/main/resources/META-INF/spring.factories

@@ -8,4 +8,7 @@ io.spring.initializr.generator.spring.code.java.JavaProjectGenerationConfigurati
 io.spring.initializr.generator.spring.code.kotlin.KotlinProjectGenerationConfiguration,\
 io.spring.initializr.generator.spring.configuration.ApplicationConfigurationProjectGenerationConfiguration,\
 io.spring.initializr.generator.spring.documentation.HelpDocumentProjectGenerationConfiguration,\
-io.spring.initializr.generator.spring.scm.git.GitProjectGenerationConfiguration
+io.spring.initializr.generator.spring.scm.git.GitProjectGenerationConfiguration
+
+org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
+io.spring.initializr.generator.spring.autoconfigure.GeneratorSpringAutoConfiguration

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/AbstractComplianceTests.java

@@ -27,6 +27,8 @@ import io.spring.initializr.generator.language.Language;
 import io.spring.initializr.generator.project.ProjectDescription;
 import io.spring.initializr.generator.project.ProjectGenerationContext;
 import io.spring.initializr.generator.project.ResolvedProjectDescription;
+import io.spring.initializr.generator.spring.code.kotlin.InitializrMetadataKotlinVersionResolver;
+import io.spring.initializr.generator.spring.code.kotlin.KotlinVersionResolver;
 import io.spring.initializr.generator.spring.test.InitializrMetadataTestBuilder;
 import io.spring.initializr.generator.spring.test.ProjectAssert;
 import io.spring.initializr.generator.test.project.ProjectGeneratorTester;
@@ -102,6 +104,8 @@ public abstract class AbstractComplianceTests {
 				context.getBean(ResolvedProjectDescription.class).getPlatformVersion()));
 		context.registerBean(IndentingWriterFactory.class,
 				() -> IndentingWriterFactory.create(new SimpleIndentStrategy("\t")));
+		context.registerBean(KotlinVersionResolver.class,
+				() -> new InitializrMetadataKotlinVersionResolver(() -> metadata));
 	}
 
 	private void setupProjectDescription(Language language, String version, BuildSystem buildSystem,