Add generation context interface

Add `GenerationContext` interface and `DefaultGenerationContext`
implementation as the central entry point for AOT processing.

See gh-28414

spring-core/src/test/java/org/springframework/aot/generate/DefaultGenerationContextTests.java

@@ -0,0 +1,105 @@
+/*
+ * 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.aot.generate;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.aot.hint.RuntimeHints;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
+/**
+ * Tests for {@link DefaultGenerationContext}.
+ *
+ * @author Phillip Webb
+ * @author Stephane Nicoll
+ */
+class DefaultGenerationContextTests {
+
+	private final ClassNameGenerator classNameGenerator = new ClassNameGenerator();
+
+	private final GeneratedFiles generatedFiles = new InMemoryGeneratedFiles();
+
+	private final RuntimeHints runtimeHints = new RuntimeHints();
+
+
+	@Test
+	void createWithOnlyGeneratedFilesCreatesContext() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.generatedFiles);
+		assertThat(context.getClassNameGenerator())
+				.isInstanceOf(ClassNameGenerator.class);
+		assertThat(context.getGeneratedFiles()).isSameAs(this.generatedFiles);
+		assertThat(context.getRuntimeHints()).isInstanceOf(RuntimeHints.class);
+	}
+
+	@Test
+	void createCreatesContext() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.classNameGenerator, this.generatedFiles, this.runtimeHints);
+		assertThat(context.getClassNameGenerator()).isNotNull();
+		assertThat(context.getGeneratedFiles()).isNotNull();
+		assertThat(context.getRuntimeHints()).isNotNull();
+	}
+
+	@Test
+	void createWhenClassNameGeneratorIsNullThrowsException() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> new DefaultGenerationContext(null, this.generatedFiles,
+						this.runtimeHints))
+				.withMessage("'classNameGenerator' must not be null");
+	}
+
+	@Test
+	void createWhenGeneratedFilesIsNullThrowsException() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> new DefaultGenerationContext(this.classNameGenerator,
+						null, this.runtimeHints))
+				.withMessage("'generatedFiles' must not be null");
+	}
+
+	@Test
+	void createWhenRuntimeHintsIsNullThrowsException() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> new DefaultGenerationContext(this.classNameGenerator,
+						this.generatedFiles, null))
+				.withMessage("'runtimeHints' must not be null");
+	}
+
+	@Test
+	void getClassNameGeneratorReturnsClassNameGenerator() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.classNameGenerator, this.generatedFiles, this.runtimeHints);
+		assertThat(context.getClassNameGenerator()).isSameAs(this.classNameGenerator);
+	}
+
+	@Test
+	void getGeneratedFilesReturnsGeneratedFiles() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.classNameGenerator, this.generatedFiles, this.runtimeHints);
+		assertThat(context.getGeneratedFiles()).isSameAs(this.generatedFiles);
+	}
+
+	@Test
+	void getRuntimeHintsReturnsRuntimeHints() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.classNameGenerator, this.generatedFiles, this.runtimeHints);
+		assertThat(context.getRuntimeHints()).isSameAs(this.runtimeHints);
+	}
+
+}