Add shared test processor

This commit adds a simple annotation processor that can be used to run
more fine grained assertions.

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/TypeUtilsTests.java

@@ -18,15 +18,9 @@ package org.springframework.boot.configurationprocessor;
 
 import java.io.IOException;
 import java.time.Duration;
-import java.util.Set;
 import java.util.function.BiConsumer;
 
-import javax.annotation.processing.AbstractProcessor;
-import javax.annotation.processing.ProcessingEnvironment;
 import javax.annotation.processing.RoundEnvironment;
-import javax.annotation.processing.SupportedAnnotationTypes;
-import javax.annotation.processing.SupportedSourceVersion;
-import javax.lang.model.SourceVersion;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.TypeElement;
 
@@ -35,6 +29,7 @@ import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
 
 import org.springframework.boot.configurationprocessor.TypeUtils.TypeDescriptor;
+import org.springframework.boot.configurationprocessor.test.TestableAnnotationProcessor;
 import org.springframework.boot.configurationsample.generic.AbstractGenericProperties;
 import org.springframework.boot.configurationsample.generic.AbstractIntermediateGenericProperties;
 import org.springframework.boot.configurationsample.generic.SimpleGenericProperties;
@@ -102,35 +97,10 @@ public class TypeUtilsTests {
 
 	private void process(Class<?> target,
 			BiConsumer<RoundEnvironment, TypeUtils> consumer) throws IOException {
-		TestProcessor processor = new TestProcessor(consumer);
+		TestableAnnotationProcessor<TypeUtils> processor = new TestableAnnotationProcessor<>(
+				consumer, TypeUtils::new);
 		TestCompiler compiler = new TestCompiler(this.temporaryFolder);
 		compiler.getTask(target).call(processor);
 	}
 
-	@SupportedAnnotationTypes("*")
-	@SupportedSourceVersion(SourceVersion.RELEASE_8)
-	private final class TestProcessor extends AbstractProcessor {
-
-		private final BiConsumer<RoundEnvironment, TypeUtils> typeUtilsConsumer;
-
-		private TypeUtils typeUtils;
-
-		private TestProcessor(BiConsumer<RoundEnvironment, TypeUtils> typeUtils) {
-			this.typeUtilsConsumer = typeUtils;
-		}
-
-		@Override
-		public synchronized void init(ProcessingEnvironment env) {
-			this.typeUtils = new TypeUtils(env);
-		}
-
-		@Override
-		public boolean process(Set<? extends TypeElement> annotations,
-				RoundEnvironment roundEnv) {
-			this.typeUtilsConsumer.accept(roundEnv, this.typeUtils);
-			return false;
-		}
-
-	}
-
 }

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/test/TestableAnnotationProcessor.java

@@ -0,0 +1,66 @@
+/*
+ * 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
+ *
+ *      http://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.configurationprocessor.test;
+
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.ProcessingEnvironment;
+import javax.annotation.processing.Processor;
+import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedAnnotationTypes;
+import javax.annotation.processing.SupportedSourceVersion;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.TypeElement;
+
+/**
+ * A testable {@link Processor}.
+ *
+ * @param <T> the type of element to help writing assertions
+ * @author Stephane Nicoll
+ */
+@SupportedAnnotationTypes("*")
+@SupportedSourceVersion(SourceVersion.RELEASE_8)
+public class TestableAnnotationProcessor<T> extends AbstractProcessor {
+
+	private final BiConsumer<RoundEnvironment, T> consumer;
+
+	private final Function<ProcessingEnvironment, T> factory;
+
+	private T target;
+
+	public TestableAnnotationProcessor(BiConsumer<RoundEnvironment, T> consumer,
+			Function<ProcessingEnvironment, T> factory) {
+		this.consumer = consumer;
+		this.factory = factory;
+	}
+
+	@Override
+	public synchronized void init(ProcessingEnvironment env) {
+		this.target = this.factory.apply(env);
+	}
+
+	@Override
+	public boolean process(Set<? extends TypeElement> annotations,
+			RoundEnvironment roundEnv) {
+		this.consumer.accept(roundEnv, this.target);
+		return false;
+	}
+
+}