Migrate AOT tests to use GeneratedClasses and refine/polish AOT APIs

Migrate all AOT tests to make use of `GeneratedClasses` rather than
directly generating Java files. This commit also refines and polishes
AOT APIs to being greater consistency.

Specifically:

	- The `MethodGenerator` interface has been removed in favor of
	  working directly with `GeneratedMethods`.
	- The visibility of several constructors and methods has been
	  reduced to package-private.
	- The `using(...)` and `builder` methods have been removed in
	  favor of setting the `Consumer` callbacks directly as
	  constructor arguments.
	- Variable names for builders are now named `type` or `method`
	  depending on what they're building.

Closes gh-28831

spring-beans/src/testFixtures/java/org/springframework/beans/testfixture/beans/factory/aot/DeferredTypeBuilder.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2002-2022 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.beans.testfixture.beans.factory.aot;
+
+import java.util.function.Consumer;
+
+import org.springframework.javapoet.TypeSpec;
+import org.springframework.util.Assert;
+
+/**
+ * {@link TypeSpec.Builder} {@link Consumer} that can be used to defer the to
+ * another consumer that is set at a later point.
+ *
+ * @author Phillip Webb
+ * @since 6.0
+ */
+public class DeferredTypeBuilder implements Consumer<TypeSpec.Builder> {
+
+	private Consumer<TypeSpec.Builder> type;
+
+	@Override
+	public void accept(TypeSpec.Builder type) {
+		Assert.notNull(this.type, "No type builder set");
+		this.type.accept(type);
+	}
+
+	public void set(Consumer<TypeSpec.Builder> type) {
+		this.type = type;
+	}
+
+}

spring-beans/src/testFixtures/java/org/springframework/beans/testfixture/beans/factory/aot/MockBeanFactoryInitializationCode.java

@@ -20,7 +20,9 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import org.springframework.aot.generate.GeneratedClass;
 import org.springframework.aot.generate.GeneratedMethods;
+import org.springframework.aot.generate.GenerationContext;
 import org.springframework.aot.generate.MethodReference;
 import org.springframework.beans.factory.aot.BeanFactoryInitializationCode;
 
@@ -28,16 +30,33 @@ import org.springframework.beans.factory.aot.BeanFactoryInitializationCode;
  * Mock {@link BeanFactoryInitializationCode} implementation.
  *
  * @author Stephane Nicoll
+ * @author Phillip Webb
  */
 public class MockBeanFactoryInitializationCode implements BeanFactoryInitializationCode {
 
-	private final GeneratedMethods generatedMethods = new GeneratedMethods();
+	private final GeneratedClass generatedClass;
 
 	private final List<MethodReference> initializers = new ArrayList<>();
 
+	private final DeferredTypeBuilder typeBuilder = new DeferredTypeBuilder();
+
+
+	public MockBeanFactoryInitializationCode(GenerationContext generationContext) {
+		this.generatedClass = generationContext.getGeneratedClasses().addForFeature("TestCode", typeBuilder);
+	}
+
+
+	public DeferredTypeBuilder getTypeBuilder() {
+		return typeBuilder;
+	}
+
+	public GeneratedClass getGeneratedClass() {
+		return generatedClass;
+	}
+
 	@Override
-	public GeneratedMethods getMethodGenerator() {
-		return this.generatedMethods;
+	public GeneratedMethods getMethods() {
+		return this.generatedClass.getMethods();
 	}
 
 	@Override

spring-beans/src/testFixtures/java/org/springframework/beans/testfixture/beans/factory/aot/MockBeanRegistrationCode.java

@@ -20,7 +20,9 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import org.springframework.aot.generate.GeneratedClass;
 import org.springframework.aot.generate.GeneratedMethods;
+import org.springframework.aot.generate.GenerationContext;
 import org.springframework.aot.generate.MethodReference;
 import org.springframework.beans.factory.aot.BeanRegistrationCode;
 import org.springframework.javapoet.ClassName;
@@ -33,28 +35,34 @@ import org.springframework.javapoet.ClassName;
  */
 public class MockBeanRegistrationCode implements BeanRegistrationCode {
 
-	private final ClassName className;
-
-	private final GeneratedMethods generatedMethods = new GeneratedMethods();
+	private final GeneratedClass generatedClass;
 
 	private final List<MethodReference> instancePostProcessors = new ArrayList<>();
 
-	public MockBeanRegistrationCode(ClassName className) {
-		this.className = className;
+	private final DeferredTypeBuilder typeBuilder = new DeferredTypeBuilder();
+
+
+	public MockBeanRegistrationCode(GenerationContext generationContext) {
+		this.generatedClass = generationContext.getGeneratedClasses().addForFeature("TestCode", this.typeBuilder);
 	}
 
-	public MockBeanRegistrationCode() {
-		this(ClassName.get("com.example", "Test"));
+
+	public DeferredTypeBuilder getTypeBuilder() {
+		return typeBuilder;
+	}
+
+	public GeneratedClass getGeneratedClass() {
+		return this.generatedClass;
 	}
 
 	@Override
 	public ClassName getClassName() {
-		return this.className;
+		return this.generatedClass.getName();
 	}
 
 	@Override
-	public GeneratedMethods getMethodGenerator() {
-		return this.generatedMethods;
+	public GeneratedMethods getMethods() {
+		return this.generatedClass.getMethods();
 	}
 
 	@Override

spring-beans/src/testFixtures/java/org/springframework/beans/testfixture/beans/factory/aot/MockBeanRegistrationsCode.java

@@ -16,7 +16,9 @@
 
 package org.springframework.beans.testfixture.beans.factory.aot;
 
+import org.springframework.aot.generate.GeneratedClass;
 import org.springframework.aot.generate.GeneratedMethods;
+import org.springframework.aot.generate.GenerationContext;
 import org.springframework.beans.factory.aot.BeanRegistrationsCode;
 import org.springframework.javapoet.ClassName;
 
@@ -28,26 +30,32 @@ import org.springframework.javapoet.ClassName;
  */
 public class MockBeanRegistrationsCode implements BeanRegistrationsCode {
 
-	private final ClassName className;
+	private final GeneratedClass generatedClass;
 
-	private final GeneratedMethods generatedMethods = new GeneratedMethods();
+	private final DeferredTypeBuilder typeBuilder = new DeferredTypeBuilder();
 
-	public MockBeanRegistrationsCode(ClassName className) {
-		this.className = className;
+
+	public MockBeanRegistrationsCode(GenerationContext generationContext) {
+		this.generatedClass = generationContext.getGeneratedClasses().addForFeature("TestCode", this.typeBuilder);
 	}
 
-	public MockBeanRegistrationsCode() {
-		this(ClassName.get("com.example", "Test"));
+
+	public DeferredTypeBuilder getTypeBuilder() {
+		return typeBuilder;
+	}
+
+	public GeneratedClass getGeneratedClass() {
+		return this.generatedClass;
 	}
 
 	@Override
 	public ClassName getClassName() {
-		return this.className;
+		return this.generatedClass.getName();
 	}
 
 	@Override
-	public GeneratedMethods getMethodGenerator() {
-		return this.generatedMethods;
+	public GeneratedMethods getMethods() {
+		return this.generatedClass.getMethods();
 	}
 
 }