Introduce MonoFromFutureSupplier{,Boolean} Refaster rules (#1244)

PicnicSupermarket · Jul 20, 2024 · 4b1c892 · 4b1c892
1 parent 2b6b8de
commit 4b1c892
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diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java
@@ -33,6 +33,7 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
@@ -1904,4 +1905,41 @@ Duration after(StepVerifier.LastStep step, Duration duration) {
       return step.verifyTimeout(duration);
     }
   }
+
+  /**
+   * Prefer {@link Mono#fromFuture(Supplier)} over {@link Mono#fromFuture(CompletableFuture)}, as
+   * the former may defer initiation of the asynchornous computation until subscription.
+   */
+  static final class MonoFromFutureSupplier<T> {
+    // XXX: Constrain the `future` parameter using `@NotMatches(IsIdentityOperation.class)` once
+    // `IsIdentityOperation` no longer matches nullary method invocations.
+    @BeforeTemplate
+    Mono<T> before(CompletableFuture<T> future) {
+      return Mono.fromFuture(future);
+    }
+
+    @AfterTemplate
+    Mono<T> after(CompletableFuture<T> future) {
+      return Mono.fromFuture(() -> future);
+    }
+  }
+
+  /**
+   * Prefer {@link Mono#fromFuture(Supplier, boolean)} over {@link
+   * Mono#fromFuture(CompletableFuture, boolean)}, as the former may defer initiation of the
+   * asynchornous computation until subscription.
+   */
+  static final class MonoFromFutureSupplierBoolean<T> {
+    // XXX: Constrain the `future` parameter using `@NotMatches(IsIdentityOperation.class)` once
+    // `IsIdentityOperation` no longer matches nullary method invocations.
+    @BeforeTemplate
+    Mono<T> before(CompletableFuture<T> future, boolean suppressCancel) {
+      return Mono.fromFuture(future, suppressCancel);
+    }
+
+    @AfterTemplate
+    Mono<T> after(CompletableFuture<T> future, boolean suppressCancel) {
+      return Mono.fromFuture(() -> future, suppressCancel);
+    }
+  }
 }
diff --git a/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java b/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
@@ -21,6 +21,7 @@
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CompletableFuture;
 import java.util.function.Supplier;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -651,4 +652,12 @@ Duration testStepVerifierLastStepVerifyErrorMessage() {
   Duration testStepVerifierLastStepVerifyTimeout() {
     return Mono.empty().as(StepVerifier::create).expectTimeout(Duration.ZERO).verify();
   }
+
+  Mono<Void> testMonoFromFutureSupplier() {
+    return Mono.fromFuture(CompletableFuture.completedFuture(null));
+  }
+
+  Mono<Void> testMonoFromFutureSupplierBoolean() {
+    return Mono.fromFuture(CompletableFuture.completedFuture(null), true);
+  }
 }
diff --git a/...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java b/...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
@@ -23,6 +23,7 @@
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CompletableFuture;
 import java.util.function.Supplier;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -632,4 +633,12 @@ Duration testStepVerifierLastStepVerifyErrorMessage() {
   Duration testStepVerifierLastStepVerifyTimeout() {
     return Mono.empty().as(StepVerifier::create).verifyTimeout(Duration.ZERO);
   }
+
+  Mono<Void> testMonoFromFutureSupplier() {
+    return Mono.fromFuture(() -> CompletableFuture.completedFuture(null));
+  }
+
+  Mono<Void> testMonoFromFutureSupplierBoolean() {
+    return Mono.fromFuture(() -> CompletableFuture.completedFuture(null), true);
+  }
 }