✨ Remove Unused import codemod

Author: ryandens

core-codemods/src/main/java/io/codemodder/codemods/DefaultCodemods.java

@@ -41,6 +41,7 @@ public static List<Class<? extends CodeChanger>> asList() {
         PreventFileWriterLeakWithFilesCodemod.class,
         RandomizeSeedCodemod.class,
         RemoveRedundantVariableCreationCodemod.class,
+        RemoveUnusedImportCodemod.class,
         RemoveUnusedLocalVariableCodemod.class,
         RemoveUnusedPrivateMethodCodemod.class,
         RemoveUselessParenthesesCodemod.class,

core-codemods/src/main/java/io/codemodder/codemods/RemoveUnusedImportCodemod.java

@@ -0,0 +1,61 @@
+package io.codemodder.codemods;
+
+import com.github.javaparser.ast.CompilationUnit;
+import com.github.javaparser.ast.ImportDeclaration;
+import io.codemodder.Codemod;
+import io.codemodder.CodemodExecutionPriority;
+import io.codemodder.CodemodInvocationContext;
+import io.codemodder.Importance;
+import io.codemodder.NodeCollector;
+import io.codemodder.RegionNodeMatcher;
+import io.codemodder.ReviewGuidance;
+import io.codemodder.codetf.DetectorRule;
+import io.codemodder.javaparser.ChangesResult;
+import io.codemodder.providers.sonar.ProvidedSonarScan;
+import io.codemodder.providers.sonar.RuleIssues;
+import io.codemodder.providers.sonar.SonarPluginJavaParserChanger;
+import io.codemodder.providers.sonar.api.Issue;
+import javax.inject.Inject;
+
+@Codemod(
+    id = "sonar:java/remove-redundant-variable-creation-s1128",
+    reviewGuidance = ReviewGuidance.MERGE_WITHOUT_REVIEW,
+    importance = Importance.LOW,
+    executionPriority = CodemodExecutionPriority.HIGH)
+public final class RemoveUnusedImportCodemod
+    extends SonarPluginJavaParserChanger<ImportDeclaration> {
+
+  @Inject
+  public RemoveUnusedImportCodemod(
+      @ProvidedSonarScan(ruleId = "java:S1128") final RuleIssues issues) {
+    super(
+        issues,
+        ImportDeclaration.class,
+        /*
+         * This codemod uses a less strict RegionNodeMatcher because the import declaration technically starts on column
+         * 1 according to java parser but sonar reports the unused import starting from the import keyword, on column 8,
+         * which is where the unused name is actually located. Neither are technically incorrect, but we can be less
+         * strict with matching here given how relatively simple the import declaration is.
+         */
+        RegionNodeMatcher.MATCHES_LINE,
+        NodeCollector.ALL_FROM_TYPE);
+  }
+
+  @Override
+  protected DetectorRule getDetectorRule() {
+    return new DetectorRule(
+        "java:S1128",
+        "Unnecessary imports should be removed",
+        "https://rules.sonarsource.com/java/RSPEC-1128");
+  }
+
+  @Override
+  public ChangesResult onIssueFound(
+      CodemodInvocationContext context, CompilationUnit cu, ImportDeclaration node, Issue issue) {
+    if (issue.getMessage().contains(node.getNameAsString())) {
+      return cu.remove(node) ? ChangesResult.changesApplied : ChangesResult.noChanges;
+    } else {
+      return ChangesResult.noChanges;
+    }
+  }
+}

core-codemods/src/main/resources/io/codemodder/codemods/RemoveUnusedImportCodemod/description.md

@@ -0,0 +1,7 @@
+This change removes unused imports. Unused imports make the code harder to read, which will lead to confusion and bugs. We only remove variables that have no state-changing effects.
+
+Our changes look something like this:
+
+```diff
+-    import java.util.Predicate;
+```

core-codemods/src/main/resources/io/codemodder/codemods/RemoveUnusedImportCodemod/report.json

@@ -0,0 +1,8 @@
+{
+  "summary" : "Removed unused import (Sonar)",
+  "change" : "Removed unused import variable",
+  "reviewGuidanceJustification" : "There are no functional changes after this change, but the code will be easier to understand.",
+  "references" : [
+    "https://rules.sonarsource.com/java/RSPEC-1128/"
+  ]
+}

core-codemods/src/test/java/io/codemodder/codemods/RemoveUnusedImportCodemodTest.java

@@ -0,0 +1,11 @@
+package io.codemodder.codemods;
+
+import io.codemodder.testutils.CodemodTestMixin;
+import io.codemodder.testutils.Metadata;
+
+@Metadata(
+    codemodType = RemoveUnusedImportCodemod.class,
+    testResourceDir = "remove-unused-import-s1128",
+    renameTestFile = "sonar/src/main/java/ai/pixee/triage/sonar/SonarTriageProvider.java",
+    dependencies = {})
+final class RemoveUnusedImportCodemodTest implements CodemodTestMixin {}

core-codemods/src/test/resources/remove-unused-import-s1128/Test.java.after

@@ -0,0 +1,12 @@
+package ai.pixee.triage.sonar;
+
+import java.io.IOException;
+import ai.pixee.triage.TriageProvider;
+
+/** A provider for Sonar. */
+public final class SonarTriageProvider implements TriageProvider {
+
+    public void triage() throws IOException {
+        System.out.println("Triage with Sonar");
+    }
+}

core-codemods/src/test/resources/remove-unused-import-s1128/Test.java.before

@@ -0,0 +1,13 @@
+package ai.pixee.triage.sonar;
+
+import java.io.IOException;
+import java.util.function.Predicate;
+import ai.pixee.triage.TriageProvider;
+
+/** A provider for Sonar. */
+public final class SonarTriageProvider implements TriageProvider {
+
+    public void triage() throws IOException {
+        System.out.println("Triage with Sonar");
+    }
+}

core-codemods/src/test/resources/remove-unused-import-s1128/sonar-issues.json

@@ -0,0 +1 @@
+{"total":1,"p":1,"ps":100,"paging":{"pageIndex":1,"pageSize":100,"total":1},"effortTotal":1,"debtTotal":1,"issues":[{"key":"AY6qgnZ1S4TzKH4OoTdU","rule":"java:S1128","severity":"MINOR","component":"pixee_triage:sonar/src/main/java/ai/pixee/triage/sonar/SonarTriageProvider.java","project":"pixee_triage","line":23,"hash":"33f8371bb11c686cc89f1601a8476b8b","textRange":{"startLine":4,"endLine":4,"startOffset":7,"endOffset":35},"flows":[],"status":"OPEN","message":"Remove this unused import 'java.util.function.Predicate'.","effort":"1min","debt":"1min","author":"[email protected]","tags":["unused"],"creationDate":"2024-04-04T21:06:25+0200","updateDate":"2024-04-04T21:07:21+0200","type":"CODE_SMELL","organization":"pixee","pullRequest":"13","cleanCodeAttribute":"CLEAR","cleanCodeAttributeCategory":"INTENTIONAL","impacts":[{"softwareQuality":"MAINTAINABILITY","severity":"LOW"}]}],"components":[{"organization":"pixee","key":"pixee_triage","uuid":"AY6qghtlrWyjshUAn-MS","enabled":true,"qualifier":"TRK","name":"triage","longName":"triage","pullRequest":"13"},{"organization":"pixee","key":"pixee_triage:sonar/src/main/java/ai/pixee/triage/sonar/SonarTriageProvider.java","uuid":"AY6qgnRLS4TzKH4OoTZ_","enabled":true,"qualifier":"FIL","name":"SonarTriageProvider.java","longName":"sonar/src/main/java/ai/pixee/triage/sonar/SonarTriageProvider.java","path":"sonar/src/main/java/ai/pixee/triage/sonar/SonarTriageProvider.java","pullRequest":"13"}],"organizations":[{"key":"pixee","name":"Pixee"}],"facets":[]}

framework/codemodder-base/src/main/java/io/codemodder/RegionNodeMatcher.java

@@ -32,4 +32,6 @@ public interface RegionNodeMatcher {
       (region, range) ->
           region.start().line() == range.begin.line
               && region.start().column() == range.begin.column;
+
+  RegionNodeMatcher MATCHES_LINE = (region, range) -> region.start().line() == range.begin.line;
 }