migrate recipe as-is

Author: timo-a

src/main/java/org/openrewrite/java/migrate/lombok/UseNoArgsConstructor.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.java.migrate.lombok;
+
+import lombok.AccessLevel;
+import lombok.EqualsAndHashCode;
+import lombok.Value;
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.Recipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.java.JavaIsoVisitor;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.java.JavaTemplate;
+import org.openrewrite.java.tree.J;
+
+import static java.util.Comparator.comparing;
+
+@Value
+@EqualsAndHashCode(callSuper = false)
+public class UseNoArgsConstructor extends Recipe {
+
+    @Override
+    public String getDisplayName() {
+        //language=markdown
+        return "Use `@NoArgsConstructor` where applicable";
+    }
+
+    @Override
+    public String getDescription() {
+        //language=markdown
+        return "Prefer the lombok annotation `@NoArgsConstructor` over explicitly written out constructors.\n" +
+                "This recipe does not create annotations for implicit constructors.";
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        return new JavaIsoVisitor<ExecutionContext>() {
+            public static final String FOUND_EMPTY_CONSTRUCTOR = "FOUND_EMPTY_CONSTRUCTOR";
+
+
+            @Override
+            public J.ClassDeclaration visitClassDeclaration(J.ClassDeclaration classDecl, ExecutionContext ctx) {
+                J.ClassDeclaration classDeclAfterVisit = super.visitClassDeclaration(classDecl, ctx);
+
+                J.MethodDeclaration message = getCursor().pollMessage(FOUND_EMPTY_CONSTRUCTOR);
+
+                //if no constructor is found return immediately
+                if (message == null) {
+                    return classDecl;//since nothing changed the original can be returned
+                }
+
+                maybeAddImport("lombok.NoArgsConstructor");
+
+                AccessLevel accessLevel = LombokUtils.getAccessLevel(message);
+
+                return getAnnotation(accessLevel).apply(
+                        updateCursor(classDeclAfterVisit),
+                        classDeclAfterVisit.getCoordinates().addAnnotation(comparing(J.Annotation::getSimpleName)));
+            }
+
+            private JavaTemplate getAnnotation(AccessLevel accessLevel) {
+
+                JavaTemplate.Builder builder = AccessLevel.PUBLIC.equals(accessLevel)
+                        ? JavaTemplate.builder("@NoArgsConstructor()\n")
+                        : JavaTemplate.builder("@NoArgsConstructor(access = AccessLevel." + accessLevel.name() + ")\n")
+                        .imports("lombok.AccessLevel");
+
+                return builder
+                        .imports("lombok.NoArgsConstructor")
+                        .javaParser(JavaParser.fromJavaVersion()
+                                .classpath("lombok"))
+                        .build();
+            }
+
+            @Override
+            public J.MethodDeclaration visitMethodDeclaration(J.MethodDeclaration method, ExecutionContext ctx) {
+                assert method.getMethodType() != null;
+                if (method.getMethodType().getName().equals("<constructor>") //it's a constructor
+                        && method.getParameters().get(0) instanceof J.Empty  //no parameters
+                        && method.getBody().getStatements().isEmpty()        //no side effects (=> does nothing)
+                ) {
+                    getCursor().putMessageOnFirstEnclosing(J.ClassDeclaration.class, FOUND_EMPTY_CONSTRUCTOR, method);
+                    return null;
+                }
+                return super.visitMethodDeclaration(method, ctx);
+            }
+
+        };
+    }
+
+}

src/test/java/org/openrewrite/java/migrate/lombok/UseNoArgsConstructorTest.java

@@ -0,0 +1,133 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.openrewrite.java.migrate.lombok;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class UseNoArgsConstructorTest implements RewriteTest {
+
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec.recipe(new UseNoArgsConstructor())
+          .parser(JavaParser.fromJavaVersion().logCompilationWarningsAndErrors(true));
+    }
+
+    @DocumentExample
+    @Test
+    void replaceEmptyPublicConstructor() {
+        rewriteRun(// language=java
+          java(
+            """
+              class A {
+                  public A() {}
+              }
+              """,
+            """
+              import lombok.NoArgsConstructor;
+
+              @NoArgsConstructor()
+              class A {
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void keepNonEmptyPublicConstructor() {
+        rewriteRun(
+          java(
+            """
+              class A {
+
+                  int foo;
+
+                  public A() {
+                      foo = 7;
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void replaceEmptyProtectedConstructor() {
+        rewriteRun(
+          java(
+            """
+              class A {
+                  protected A() {}
+              }
+              """,
+            """
+              import lombok.NoArgsConstructor;
+
+              @NoArgsConstructor(access = AccessLevel.PROTECTED)
+              class A {
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void replaceEmptyPrivateConstructor() {
+        rewriteRun(
+          java(
+            """
+              class A {
+                  private A() {}
+              }
+              """,
+            """
+              import lombok.NoArgsConstructor;
+
+              @NoArgsConstructor(access = AccessLevel.PRIVATE)
+              class A {
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void replaceEmptyPackageConstructor() {
+        rewriteRun(
+          java(
+            """
+              class A {
+                  A() {}
+              }
+              """,
+            """
+              import lombok.NoArgsConstructor;
+
+              @NoArgsConstructor(access = AccessLevel.PACKAGE)
+              class A {
+              }
+              """
+          )
+        );
+    }
+
+}