feat: Add CollectionsEmptyConstantsProcessor (SonarSource rule 1596)

docs/HANDLED_RULES.md

@@ -24,6 +24,7 @@ Sorald can currently repair violations of the following rules:
     * ["toString()" and "clone()" methods should not return null](#tostring-and-clone-methods-should-not-return-null-sonar-rule-2225) ([Sonar Rule 2225](https://rules.sonarsource.com/java/tag/multi-threading/RSPEC-2225))
 * [Code Smell](#code-smell)
     * [Collection.isEmpty() should be used to test for emptiness](#collectionisempty-should-be-used-to-test-for-emptiness-sonar-rule-1155httpsrulessonarsourcecomjavarspec-1155) ([Sonar Rule 1155](https://rules.sonarsource.com/java/RSPEC-1155))
+    * ["Collections.EMPTY_LIST", "EMPTY_MAP", and "EMPTY_SET" should not be used](#collectionsempty_list-empty_map-and-empty_set-should-not-be-used-sonar-rule-1596httpsrulessonarsourcecomjavarspec-1596) ([Sonar Rule 1596](https://rules.sonarsource.com/java/RSPEC-1596))
     * [Fields in a "Serializable" class should either be transient or serializable](#fields-in-a-serializable-class-should-either-be-transient-or-serializable-sonar-rule-1948) ([Sonar Rule 1948](https://rules.sonarsource.com/java/RSPEC-1948))
     * [Unused assignments should be removed](#unused-assignments-should-be-removed-sonar-rule-1854) ([Sonar Rule 1854](https://rules.sonarsource.com/java/RSPEC-1854))
     * [Unused local variables should be removed](#unused-local-variables-should-be-removed-sonar-rule-1481) ([Sonar Rule 1481](https://rules.sonarsource.com/java/RSPEC-1481))
@@ -448,6 +449,22 @@ Example:
 
 ------
 
+#### "Collections.EMPTY_LIST", "EMPTY_MAP", and "EMPTY_SET" should not be used ([Sonar Rule 1596](https://rules.sonarsource.com/java/RSPEC-1596))
+
+The `EMPTY_...` fields from `Collections` return raw types, so they are replaced by the `empty...()` methods that return generic ones.
+
+Example:
+```diff
+- List<String> collection1 = Collections.EMPTY_LIST;  // Noncompliant
+- Map<String, String> collection2 = Collections.EMPTY_MAP;  // Noncompliant
+- Set<String> collection3 = Collections.EMPTY_SET;  // Noncompliant
++ List<String> collection1 = Collections.emptyList();
++ Map<String, String> collection2 = Collections.emptyMap();
++ Set<String> collection3 = Collections.emptySet();
+```
+
+------
+
 #### Fields in a "Serializable" class should either be transient or serializable ([Sonar Rule 1948](https://rules.sonarsource.com/java/RSPEC-1948))
 
 The repair adds the modifier `transient` to all non-serializable

src/main/java/sorald/Processors.java

@@ -21,6 +21,7 @@ private Processors() {}
                             put(1217, ThreadRunProcessor.class);
                             put(1444, PublicStaticFieldShouldBeFinalProcessor.class);
                             put(1481, UnusedLocalVariableProcessor.class);
+                            put(1596, CollectionsEmptyConstantsProcessor.class);
                             put(1656, SelfAssignementProcessor.class);
                             put(1854, DeadStoreProcessor.class);
                             put(1860, SynchronizationOnStringOrBoxedProcessor.class);
@@ -47,7 +48,7 @@ private Processors() {}
 
     // GENERATED FIELD
     public static final String RULE_DESCRIPTIONS =
-            "1118: Utility classes should not have public constructors\n\t(incomplete: Only handles implicit public constructor)\n1132: Strings literals should be placed on the left side when checking for equality\n1155: Collection.isEmpty() should be used to test for emptiness\n1217: \"Thread.run()\" should not be called directly\n1444: \"public static\" fields should be constant\n\t(incomplete: does not fix variable naming)\n1481: Unused local variables should be removed\n1656: Variables should not be self-assigned\n1854: Unused assignments should be removed\n1860: Synchronization should not be based on Strings or boxed primitives\n1948: Fields in a \"Serializable\" class should either be transient or serializable\n2057: Every class implementing Serializable should declare a static final serialVersionUID.\n\t(incomplete: This processor does not address the case where the class already has a serialVersionUID with a non long type.)\n2095: Resources should be closed\n2097: \"equals(Object obj)\" should test argument type\n2111: \"BigDecimal(double)\" should not be used\n2116: \"hashCode\" and \"toString\" should not be called on array instances\n2142: \"InterruptedException\" should not be ignored\n2164: Math should not be performed on floats\n2167: \"compareTo\" should not return \"Integer.MIN_VALUE\"\n2184: Math operands should be cast before assignment\n2204: \".equals()\" should not be used to test the values of \"Atomic\" classes\n2225: \"toString()\" and \"clone()\" methods should not return null\n\t(incomplete: does not fix null returning clone())\n2272: \"Iterator.next()\" methods should throw \"NoSuchElementException\"\n2755: XML parsers should not be vulnerable to XXE attacks\n\t(incomplete: This processor is a WIP and currently supports a subset of rule 2755. See Sorald\'s documentation for details.)\n3032: JEE applications should not \"getClassLoader\"\n3067: \"getClass\" should not be used for synchronization\n3984: Exception should not be created without being thrown\n4973: Strings and Boxed types should be compared using \"equals()\"";
+            "1118: Utility classes should not have public constructors\n\t(incomplete: Only handles implicit public constructor)\n1132: Strings literals should be placed on the left side when checking for equality\n1155: Collection.isEmpty() should be used to test for emptiness\n1217: \"Thread.run()\" should not be called directly\n1444: \"public static\" fields should be constant\n\t(incomplete: does not fix variable naming)\n1481: Unused local variables should be removed\n1596: \"Collections.EMPTY_LIST\", \"EMPTY_MAP\", and \"EMPTY_SET\" should not be used\n1656: Variables should not be self-assigned\n1854: Unused assignments should be removed\n1860: Synchronization should not be based on Strings or boxed primitives\n1948: Fields in a \"Serializable\" class should either be transient or serializable\n2057: Every class implementing Serializable should declare a static final serialVersionUID.\n\t(incomplete: This processor does not address the case where the class already has a serialVersionUID with a non long type.)\n2095: Resources should be closed\n2097: \"equals(Object obj)\" should test argument type\n2111: \"BigDecimal(double)\" should not be used\n2116: \"hashCode\" and \"toString\" should not be called on array instances\n2142: \"InterruptedException\" should not be ignored\n2164: Math should not be performed on floats\n2167: \"compareTo\" should not return \"Integer.MIN_VALUE\"\n2184: Math operands should be cast before assignment\n2204: \".equals()\" should not be used to test the values of \"Atomic\" classes\n2225: \"toString()\" and \"clone()\" methods should not return null\n\t(incomplete: does not fix null returning clone())\n2272: \"Iterator.next()\" methods should throw \"NoSuchElementException\"\n2755: XML parsers should not be vulnerable to XXE attacks\n\t(incomplete: This processor is a WIP and currently supports a subset of rule 2755. See Sorald\'s documentation for details.)\n3032: JEE applications should not \"getClassLoader\"\n3067: \"getClass\" should not be used for synchronization\n3984: Exception should not be created without being thrown\n4973: Strings and Boxed types should be compared using \"equals()\"";
 
     public static Class<? extends SoraldAbstractProcessor<?>> getProcessor(int key) {
         return RULE_KEY_TO_PROCESSOR.get(key);

src/main/java/sorald/processor/CollectionsEmptyConstantsProcessor.java

@@ -0,0 +1,33 @@
+package sorald.processor;
+
+import java.util.Collections;
+import sorald.annotations.ProcessorAnnotation;
+import spoon.reflect.code.*;
+import spoon.reflect.declaration.CtMethod;
+import spoon.reflect.declaration.CtType;
+
+@ProcessorAnnotation(
+        key = 1596,
+        description =
+                "\"Collections.EMPTY_LIST\", \"EMPTY_MAP\", and \"EMPTY_SET\" should not be used")
+public class CollectionsEmptyConstantsProcessor extends SoraldAbstractProcessor<CtFieldAccess<?>> {
+
+    @Override
+    protected void repairInternal(CtFieldAccess<?> element) {
+        CtType<?> collectionsType = getFactory().Class().get(Collections.class);
+
+        CtMethod<?> methodToBeCalled;
+        if (element.getVariable().getSimpleName().equals("EMPTY_LIST")) {
+            methodToBeCalled = collectionsType.getMethodsByName("emptyList").get(0);
+        } else if (element.getVariable().getSimpleName().equals("EMPTY_MAP")) {
+            methodToBeCalled = collectionsType.getMethodsByName("emptyMap").get(0);
+        } else {
+            methodToBeCalled = collectionsType.getMethodsByName("emptySet").get(0);
+        }
+
+        CtInvocation<?> newInvocation =
+                getFactory().createInvocation(element.getTarget(), methodToBeCalled.getReference());
+
+        element.replace(newInvocation);
+    }
+}

src/test/resources/processor_test_files/1596_CollectionsEmptyConstants/CollectionsEmptyConstants.java

@@ -0,0 +1,12 @@
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+public class CollectionsEmptyConstants {
+    public static void main(String[] args) {
+        List<String> collection1 = Collections.EMPTY_LIST;  // Noncompliant
+        Map<String, String> collection2 = Collections.EMPTY_MAP;  // Noncompliant
+        Set<String> collection3 = Collections.EMPTY_SET;  // Noncompliant
+    }
+}

src/test/resources/processor_test_files/1596_CollectionsEmptyConstants/CollectionsEmptyConstants.java.expected

@@ -0,0 +1,12 @@
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+public class CollectionsEmptyConstants {
+    public static void main(String[] args) {
+        List<String> collection1 = Collections.emptyList();
+        Map<String, String> collection2 = Collections.emptyMap();
+        Set<String> collection3 = Collections.emptySet();
+    }
+}