Introduce MapGetOrDefault Refaster rule (#439)

Fixes #431.
PicnicSupermarket · Jan 6, 2023 · feb9abf · feb9abf
1 parent 560f52b
commit feb9abf
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Showing 3 changed files with 31 additions and 2 deletions.
diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/MapRules.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/MapRules.java
@@ -1,5 +1,7 @@
 package tech.picnic.errorprone.refasterrules;
 
+import static java.util.Objects.requireNonNullElse;
+
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -43,6 +45,21 @@ V after(Map<K, V> map, T key) {
     }
   }
 
+  /** Prefer {@link Map#getOrDefault(Object, Object)} over more contrived alternatives. */
+  // XXX: Note that `requireNonNullElse` throws an NPE if the second argument is `null`, while the
+  // alternative does not.
+  static final class MapGetOrDefault<K, V, T> {
+    @BeforeTemplate
+    V before(Map<K, V> map, T key, V defaultValue) {
+      return requireNonNullElse(map.get(key), defaultValue);
+    }
+
+    @AfterTemplate
+    V after(Map<K, V> map, T key, V defaultValue) {
+      return map.getOrDefault(key, defaultValue);
+    }
+  }
+
   /** Prefer {@link Map#isEmpty()} over more contrived alternatives. */
   static final class MapIsEmpty<K, V> {
     @BeforeTemplate

diff --git a/...ne-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/MapRulesTestInput.java b/...ne-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/MapRulesTestInput.java
@@ -1,5 +1,7 @@
 package tech.picnic.errorprone.refasterrules;
 
+import static java.util.Objects.requireNonNullElse;
+
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import java.math.RoundingMode;
@@ -11,7 +13,7 @@
 final class MapRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(HashMap.class);
+    return ImmutableSet.of(HashMap.class, requireNonNullElse(null, null));
   }
 
   Map<RoundingMode, String> testCreateEnumMap() {
@@ -22,6 +24,10 @@ String testMapGetOrNull() {
     return ImmutableMap.of(1, "foo").getOrDefault("bar", null);
   }
 
+  String testMapGetOrDefault() {
+    return requireNonNullElse(ImmutableMap.of(1, "foo").get("bar"), "baz");
+  }
+
   ImmutableSet<Boolean> testMapIsEmpty() {
     return ImmutableSet.of(
         ImmutableMap.of("foo", 1).keySet().isEmpty(),

diff --git a/...e-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/MapRulesTestOutput.java b/...e-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/MapRulesTestOutput.java
@@ -1,5 +1,7 @@
 package tech.picnic.errorprone.refasterrules;
 
+import static java.util.Objects.requireNonNullElse;
+
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import java.math.RoundingMode;
@@ -12,7 +14,7 @@
 final class MapRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(HashMap.class);
+    return ImmutableSet.of(HashMap.class, requireNonNullElse(null, null));
   }
 
   Map<RoundingMode, String> testCreateEnumMap() {
@@ -23,6 +25,10 @@ String testMapGetOrNull() {
     return ImmutableMap.of(1, "foo").get("bar");
   }
 
+  String testMapGetOrDefault() {
+    return ImmutableMap.of(1, "foo").getOrDefault("bar", "baz");
+  }
+
   ImmutableSet<Boolean> testMapIsEmpty() {
     return ImmutableSet.of(
         ImmutableMap.of("foo", 1).isEmpty(),