Support programmatic GraphQLSchema creation

Prior to this commit, the `GraphQLAutoConfiguration` would only consider
the case where the GraphQL schema is read as an SDL from a configured
location.

GraphQL also supports the programmatic creation of the schema and this
case needs to be supported by the auto-configuration.

This commit updates the auto-configuration to disable the schema
creation from the SDL if a `GraphQL.Builder` bean is already contributed
by the application.

Fixes gh-4

spring-graphql-web/src/main/java/org/springframework/boot/graphql/GraphQLAutoConfiguration.java

@@ -39,25 +39,36 @@ import org.springframework.util.ResourceUtils;
 @EnableConfigurationProperties(GraphQLProperties.class)
 public class GraphQLAutoConfiguration {
 
-	@Bean
-	@ConditionalOnMissingBean
-	public RuntimeWiring runtimeWiring(ObjectProvider<RuntimeWiringCustomizer> customizers) {
-		RuntimeWiring.Builder builder = RuntimeWiring.newRuntimeWiring();
-		customizers.orderedStream().forEach(customizer -> customizer.customize(builder));
-		return builder.build();
-	}
+	@Configuration
+	@ConditionalOnMissingBean(GraphQL.Builder.class)
+	static class SdlConfiguration {
 
-	@Bean
-	public GraphQL.Builder graphQLBuilder(GraphQLProperties properties, RuntimeWiring runtimeWiring) throws FileNotFoundException {
-		File schemaFile = ResourceUtils.getFile(properties.getSchema());
-		GraphQLSchema schema = buildSchema(schemaFile, runtimeWiring);
-		return GraphQL.newGraphQL(schema);
-	}
+		@Bean
+		@ConditionalOnMissingBean
+		public RuntimeWiring runtimeWiring(ObjectProvider<RuntimeWiringCustomizer> customizers) {
+			RuntimeWiring.Builder builder = RuntimeWiring.newRuntimeWiring();
+			customizers.orderedStream().forEach(customizer -> customizer.customize(builder));
+			return builder.build();
+		}
+
+		@Bean
+		public GraphQL.Builder graphQLBuilder(GraphQLProperties properties, RuntimeWiring runtimeWiring) {
+			try {
+				File schemaFile = ResourceUtils.getFile(properties.getSchema());
+				GraphQLSchema schema = buildSchema(schemaFile, runtimeWiring);
+				return GraphQL.newGraphQL(schema);
+			}
+			catch (FileNotFoundException ex) {
+				throw new MissingGraphQLSchemaException(properties.getSchema());
+			}
+		}
+
+		private GraphQLSchema buildSchema(File schemaFile, RuntimeWiring runtimeWiring) {
+			TypeDefinitionRegistry typeRegistry = new SchemaParser().parse(schemaFile);
+			SchemaGenerator schemaGenerator = new SchemaGenerator();
+			return schemaGenerator.makeExecutableSchema(typeRegistry, runtimeWiring);
+		}
 
-	private GraphQLSchema buildSchema(File schemaFile, RuntimeWiring runtimeWiring) {
-		TypeDefinitionRegistry typeRegistry = new SchemaParser().parse(schemaFile);
-		SchemaGenerator schemaGenerator = new SchemaGenerator();
-		return schemaGenerator.makeExecutableSchema(typeRegistry, runtimeWiring);
 	}
 
 }

spring-graphql-web/src/main/java/org/springframework/boot/graphql/MissingGraphQLSchemaException.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2002-2020 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.
+ * 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 org.springframework.boot.graphql;
+
+import org.springframework.util.StringUtils;
+
+/**
+ * Exception thrown when no GraphQL schema is available.
+ */
+public class MissingGraphQLSchemaException extends RuntimeException {
+
+	private final String path;
+
+	MissingGraphQLSchemaException(String path) {
+		super(StringUtils.hasText(path) ? "Path to GraphQL schema not configured" : "Cannot find schema file at: "
+				+ path + " (please add a schema file or check your GraphQL configuration)");
+		this.path = path;
+	}
+
+	public String getPath() {
+		return this.path;
+	}
+}

spring-graphql-web/src/test/java/org/springframework/boot/graphql/GraphQLAutoConfigurationTests.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2002-2020 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.
+ * 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 org.springframework.boot.graphql;
+
+import graphql.GraphQL;
+import graphql.schema.GraphQLObjectType;
+import graphql.schema.GraphQLSchema;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import static graphql.Scalars.GraphQLString;
+import static graphql.schema.GraphQLFieldDefinition.newFieldDefinition;
+import static graphql.schema.GraphQLObjectType.newObject;
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link GraphQLAutoConfiguration}
+ */
+class GraphQLAutoConfigurationTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+			.withConfiguration(AutoConfigurations.of(GraphQLAutoConfiguration.class));
+
+
+	@Test
+	void shouldFailWhenSchemaFileIsMissing() {
+		contextRunner.run((context) -> {
+			assertThat(context).hasFailed();
+			assertThat(context).getFailure().getRootCause().isInstanceOf(MissingGraphQLSchemaException.class);
+		});
+	}
+
+	@Test
+	void shouldCreateBuilderWithSdl() {
+		contextRunner
+				.withPropertyValues("spring.graphql.schema:classpath:books/schema.graphqls")
+				.run((context) -> {
+					assertThat(context).hasSingleBean(GraphQL.Builder.class);
+				});
+	}
+
+	@Test
+	void shouldUseProgrammaticallyDefinedBuilder() {
+		contextRunner
+				.withPropertyValues("spring.graphql.schema:classpath:books/schema.graphqls")
+				.withUserConfiguration(CustomGraphQLBuilderConfiguration.class)
+				.run((context) -> {
+					assertThat(context).hasBean("customGraphQLBuilder");
+					assertThat(context).hasSingleBean(GraphQL.Builder.class);
+				});
+	}
+
+	@Configuration
+	static class CustomGraphQLBuilderConfiguration {
+
+		@Bean
+		public GraphQL.Builder customGraphQLBuilder() {
+			GraphQLObjectType queryType = newObject()
+					.name("helloWorldQuery")
+					.field(newFieldDefinition()
+							.type(GraphQLString)
+							.name("hello"))
+					.build();
+			GraphQLSchema schema = GraphQLSchema.newSchema().query(queryType).build();
+			return GraphQL.newGraphQL(schema);
+		}
+	}
+
+}