Document graphQlTester custom document source

Signed-off-by: Marco Schaeck <marco.schaeck@outlook.de>
[brian.clozel@broadcom.com: polishing docs and tests]
Signed-off-by: Brian Clozel <brian.clozel@broadcom.com>

Closes gh-1285

Author: emaarco

spring-graphql-docs/modules/ROOT/pages/testing.adoc

@@ -181,8 +181,8 @@ xref:testing.adoc#testing.requests[execute requests] using the same API, indepen
 [[testing.graphqltester.builder]]
 === Builder
 
-`GraphQlTester` defines a parent `Builder` with common configuration options for the
-builders of all extensions. It lets you configure the following:
+`GraphQlTester` defines a parent `Builder` with common configuration options for the builders of all supported transports.
+It lets you configure the following:
 
 - `errorFilter` - a predicate to suppress expected errors, so you can inspect the data
 of the response.
@@ -191,8 +191,7 @@ the classpath or from anywhere else.
 - `responseTimeout` - how long to wait for request execution to complete before timing
 out.
 
-
-
+include-code::GraphQlTesterBuilder[tag=inlineDocument,indent=0]
 
 [[testing.requests]]
 == Requests

spring-graphql-docs/src/main/java/org/springframework/graphql/docs/testing/graphqltester/builder/GraphQlTesterBuilder.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2020-present 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.graphql.docs.testing.graphqltester.builder;
+
+import java.time.Duration;
+import java.util.function.Predicate;
+
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.graphql.ResponseError;
+import org.springframework.graphql.client.GraphQlTransport;
+import org.springframework.graphql.support.DocumentSource;
+import org.springframework.graphql.support.ResourceDocumentSource;
+import org.springframework.graphql.test.tester.GraphQlTester;
+
+public class GraphQlTesterBuilder {
+
+	void inlineDocument() {
+		// tag::inlineDocument[]
+		GraphQlTransport transport = /**/ null;
+		Predicate<ResponseError> errorFilter = /**/ null;
+		ClassPathResource resource = new ClassPathResource("custom-folder/");
+		DocumentSource documentSource = new ResourceDocumentSource(resource);
+
+		GraphQlTester tester = GraphQlTester.builder(transport)
+				.documentSource(documentSource)
+				.errorFilter(errorFilter)
+				.responseTimeout(Duration.ofSeconds(5))
+				.build();
+		// end::inlineDocument[]
+	}
+
+}

spring-graphql/src/main/java/org/springframework/graphql/support/ResourceDocumentSource.java

@@ -34,10 +34,11 @@
 import org.springframework.util.FileCopyUtils;
 
 /**
- * {@link DocumentSource} that looks for a document {@link Resource} under a set
- * of locations and trying a number of different file extension.
+ * {@link DocumentSource} that searches for document {@link Resource}s across
+ * multiple locations while trying different file extensions.
  *
  * @author Rossen Stoyanchev
+ * @author Marco Schäck
  * @since 1.0.0
  */
 public class ResourceDocumentSource implements DocumentSource {
@@ -61,6 +62,15 @@ public ResourceDocumentSource() {
 		this(Collections.singletonList(new ClassPathResource("graphql/")), FILE_EXTENSIONS);
 	}
 
+	/**
+	 * Constructor with a single location and the default file extensions.
+	 * @param location the resource location
+	 * @since 2.0.0
+	 */
+	public ResourceDocumentSource(Resource location) {
+		this(Collections.singletonList(location), FILE_EXTENSIONS);
+	}
+
 	/**
 	 * Constructor with given locations and extensions.
 	 * @param locations the resource locations