Introduce Reactor ContextEmpty Refaster rule (#306)

PicnicSupermarket · Oct 23, 2022 · 0118cc6 · 0118cc6
1 parent 91e009c
commit 0118cc6
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Showing 3 changed files with 34 additions and 2 deletions.
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
@@ -5,6 +5,7 @@
 import static java.util.function.Function.identity;
 import static org.assertj.core.api.Assertions.assertThat;
 
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.MoreCollectors;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
@@ -14,6 +15,7 @@
 import com.google.errorprone.refaster.annotation.Placeholder;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.time.Duration;
+import java.util.HashMap;
 import java.util.Optional;
 import java.util.concurrent.Callable;
 import java.util.function.Consumer;
@@ -25,6 +27,7 @@
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
 import reactor.test.publisher.PublisherProbe;
+import reactor.util.context.Context;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 import tech.picnic.errorprone.refaster.matchers.ThrowsCheckedException;
 
@@ -375,6 +378,21 @@ Flux<T> after(Flux<T> flux) {
     }
   }
 
+  /** Prefer {@link reactor.util.context.Context#empty()}} over more verbose alternatives. */
+  // XXX: Consider introducing an `IsEmpty` matcher that identifies a wide range of guaranteed-empty
+  // `Collection` and `Map` expressions.
+  static final class ContextEmpty {
+    @BeforeTemplate
+    Context before() {
+      return Context.of(Refaster.anyOf(new HashMap<>(), ImmutableMap.of()));
+    }
+
+    @AfterTemplate
+    Context after() {
+      return Context.empty();
+    }
+  }
+
   /** Prefer {@link PublisherProbe#empty()}} over more verbose alternatives. */
   static final class PublisherProbeEmpty<T> {
     @BeforeTemplate

diff --git a/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java b/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
@@ -3,21 +3,24 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import java.time.Duration;
+import java.util.HashMap;
 import java.util.Optional;
 import java.util.concurrent.Callable;
 import java.util.function.Supplier;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
 import reactor.test.publisher.PublisherProbe;
+import reactor.util.context.Context;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(assertThat(0));
+    return ImmutableSet.of(assertThat(0), HashMap.class, ImmutableMap.class);
   }
 
   ImmutableSet<Mono<?>> testMonoFromSupplier() {
@@ -126,6 +129,10 @@ ImmutableSet<Flux<Integer>> testFluxOnErrorComplete() {
         Flux.just(2).onErrorResume(e -> Flux.empty()));
   }
 
+  ImmutableSet<Context> testContextEmpty() {
+    return ImmutableSet.of(Context.of(new HashMap<>()), Context.of(ImmutableMap.of()));
+  }
+
   ImmutableSet<PublisherProbe<Void>> testPublisherProbeEmpty() {
     return ImmutableSet.of(PublisherProbe.of(Mono.empty()), PublisherProbe.of(Flux.empty()));
   }

diff --git a/...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java b/...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
@@ -5,21 +5,24 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import java.time.Duration;
+import java.util.HashMap;
 import java.util.Optional;
 import java.util.concurrent.Callable;
 import java.util.function.Supplier;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
 import reactor.test.publisher.PublisherProbe;
+import reactor.util.context.Context;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(assertThat(0));
+    return ImmutableSet.of(assertThat(0), HashMap.class, ImmutableMap.class);
   }
 
   ImmutableSet<Mono<?>> testMonoFromSupplier() {
@@ -124,6 +127,10 @@ ImmutableSet<Flux<Integer>> testFluxOnErrorComplete() {
     return ImmutableSet.of(Flux.just(1).onErrorComplete(), Flux.just(2).onErrorComplete());
   }
 
+  ImmutableSet<Context> testContextEmpty() {
+    return ImmutableSet.of(Context.empty(), Context.empty());
+  }
+
   ImmutableSet<PublisherProbe<Void>> testPublisherProbeEmpty() {
     return ImmutableSet.of(PublisherProbe.empty(), PublisherProbe.empty());
   }