Allow to define "non starter" dependency

Previously, all dependencies were considered equal and enough to compile
and start the simple auto-generated boot application. There are some
corner cases such as the JDBC drivers and the new Ratpack integration.

This commit adds an extra flag on a dependency that determines if it is
a starter or not (the default is true). When no starter dependency has
been selected for the project, the root starter (`spring-boot-starter`)
is automatically added.

Closes gh-159

initializr-service/application.yml

@@ -88,10 +88,11 @@ initializr:
         - name: Ratpack
           id: ratpack
           description: Spring Boot integration for the Ratpack framework
-          versionRange: 1.2.0.RELEASE
-          version: 1.1.1
           groupId: io.ratpack
           artifactId: ratpack-spring-boot
+          version: 1.1.1
+          versionRange: 1.2.0.RELEASE
+          starter: false
         - name: Vaadin
           id: vaadin
           facets:
@@ -449,12 +450,14 @@ initializr:
           groupId: com.h2database
           artifactId: h2
           scope: runtime
+          starter: false
         - name: HSQLDB
           id: hsql
           description: HSQLDB database (with embedded support)
           groupId: org.hsqldb
           artifactId: hsqldb
           scope: runtime
+          starter: false
         - name: Apache Derby
           id: derby
           description: Apache Derby database (with embedded support)
@@ -462,12 +465,14 @@ initializr:
           artifactId: derby
           scope: runtime
           versionRange: 1.2.2.RELEASE
+          starter: false
         - name: MySQL
           id: mysql
           description: MySQL jdbc driver
           groupId: mysql
           artifactId: mysql-connector-java
           scope: runtime
+          starter: false
         - name: PostgreSQL
           id: postgresql
           description: PostgreSQL jdbc driver
@@ -475,6 +480,7 @@ initializr:
           artifactId: postgresql
           version: 9.4-1201-jdbc41
           scope: runtime
+          starter: false
     - name: Social
       content:
         - name: Facebook

initializr/src/main/groovy/io/spring/initializr/generator/ProjectRequest.groovy

@@ -174,7 +174,8 @@ class ProjectRequest {
 			resolvedDependencies << metadata.dependencies.get('web')
 			facets << 'web'
 		}
-		if (resolvedDependencies.isEmpty()) {
+		if (!resolvedDependencies.find { it.starter }) {
+			// There's no starter so we add the default one
 			addDefaultDependency()
 		}
 	}

initializr/src/main/groovy/io/spring/initializr/metadata/Dependency.groovy

@@ -65,6 +65,12 @@ class Dependency extends MetadataElement {
 
 	int weight
 
+	/**
+	 * Specify if the dependency represents a "starter", i.e. the sole presence of
+	 * that dependency is enough to bootstrap the context.
+	 */
+	boolean starter = true
+
 	List<String> keywords = []
 
 	void setScope(String scope) {

initializr/src/test/groovy/io/spring/initializr/generator/ProjectGeneratorTests.groovy

@@ -457,6 +457,37 @@ class ProjectGeneratorTests {
 				.hasRepository('http://example.com/repo')
 	}
 
+	@Test
+	void projectWithOnlyStarterDependency() {
+		def foo = new Dependency(id: 'foo', groupId: 'org.foo', artifactId: 'custom-my-starter')
+		def metadata = InitializrMetadataTestBuilder.withDefaults()
+				.addDependencyGroup('foo', foo).build()
+		projectGenerator.metadata = metadata
+
+		def request = createProjectRequest('foo')
+		generateMavenPom(request)
+				.hasDependency('org.foo', 'custom-my-starter')
+				.hasSpringBootStarterTest()
+				.hasDependenciesCount(2)
+	}
+
+	@Test
+	void projectWithOnlyNonStarterDependency() {
+		def foo = new Dependency(id: 'foo', groupId: 'org.foo', artifactId: 'foo')
+		foo.starter = false
+		def metadata = InitializrMetadataTestBuilder.withDefaults()
+				.addDependencyGroup('foo', foo).build()
+		projectGenerator.metadata = metadata
+
+		def request = createProjectRequest('foo')
+		generateMavenPom(request)
+				.hasDependency('org.foo', 'foo')
+				.hasSpringBootStarterRootDependency()
+				.hasSpringBootStarterTest()
+				.hasDependenciesCount(3)
+	}
+
+
 	PomAssert generateMavenPom(ProjectRequest request) {
 		def content = new String(projectGenerator.generateMavenPom(request))
 		new PomAssert(content).validateProjectRequest(request)

initializr/src/test/resources/metadata/config/test-default.json

@@ -60,6 +60,7 @@
             "aliases": [],
             "keywords": [],
             "weight": 0,
+            "starter": true,
             "artifactId": "spring-boot-starter-web",
             "description": "Web dependency description",
             "facets": ["web"],
@@ -72,6 +73,7 @@
             "aliases": [],
             "keywords": [],
             "weight": 0,
+            "starter": true,
             "artifactId": "spring-boot-starter-security",
             "facets": [],
             "groupId": "org.springframework.boot",
@@ -83,6 +85,7 @@
             "aliases": ["jpa"],
             "keywords": [],
             "weight": 0,
+            "starter": true,
             "artifactId": "spring-boot-starter-data-jpa",
             "facets": [],
             "groupId": "org.springframework.boot",
@@ -103,6 +106,7 @@
             "id": "org.acme:foo",
             "name": "Foo",
             "weight": 42,
+            "starter": true,
             "keywords": ["thefoo", "dafoo"],
             "scope": "compile",
             "version": "1.3.5"
@@ -111,6 +115,7 @@
             "aliases": [],
             "keywords": [],
             "weight": 0,
+            "starter": true,
             "artifactId": "bar",
             "facets": [],
             "groupId": "org.acme",
@@ -123,6 +128,7 @@
             "aliases": [],
             "keywords": [],
             "weight": 0,
+            "starter": true,
             "artifactId": "biz",
             "facets": [],
             "groupId": "org.acme",
@@ -136,6 +142,7 @@
             "aliases": [],
             "keywords": [],
             "weight": 0,
+            "starter": true,
             "artifactId": "bur",
             "facets": [],
             "groupId": "org.acme",
@@ -149,6 +156,7 @@
             "aliases": [],
             "keywords": [],
             "weight": 0,
+            "starter": true,
             "artifactId": "my-api",
             "facets": [],
             "groupId": "org.acme",