SONARPY-208 Rule: Unused local variables should be removed

pynicolas · pynicolas · commit 3daca827c50a · 2017-05-08T11:34:38.000+02:00
diff --git a/its/ruling/src/test/resources/expected/python-S1481.json b/its/ruling/src/test/resources/expected/python-S1481.json
diff --git a/its/ruling/src/test/resources/profile.xml b/its/ruling/src/test/resources/profile.xml
@@ -170,6 +170,11 @@
       <key>S1313</key>
       <priority>INFO</priority>
     </rule>
+    <rule>
+      <repositoryKey>python</repositoryKey>
+      <key>S1481</key>
+      <priority>INFO</priority>
+    </rule>
     <rule>
       <repositoryKey>python</repositoryKey>
       <key>S1578</key>
diff --git a/python-checks/src/main/java/org/sonar/python/checks/CheckList.java b/python-checks/src/main/java/org/sonar/python/checks/CheckList.java
@@ -81,6 +81,7 @@ public static Iterable<Class> getChecks() {
         DuplicatedMethodFieldNamesCheck.class,
         TooManyReturnsCheck.class,
         NeedlessPassCheck.class,
+        UnusedLocalVariableCheck.class,
         AfterJumpStatementCheck.class,
         IdenticalExpressionOnBinaryOperatorCheck.class,
         SelfAssignmentCheck.class,
diff --git a/python-checks/src/main/java/org/sonar/python/checks/UnusedLocalVariableCheck.java b/python-checks/src/main/java/org/sonar/python/checks/UnusedLocalVariableCheck.java
@@ -0,0 +1,57 @@
+/*
+ * SonarQube Python Plugin
+ * Copyright (C) 2011-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.python.checks;
+
+import com.google.common.collect.ImmutableSet;
+import com.sonar.sslr.api.AstNode;
+import com.sonar.sslr.api.AstNodeType;
+import java.util.Set;
+import org.sonar.check.Rule;
+import org.sonar.python.PythonCheck;
+import org.sonar.python.api.PythonGrammar;
+import org.sonar.python.semantic.Symbol;
+
+@Rule(key = "S1481")
+public class UnusedLocalVariableCheck extends PythonCheck {
+
+  private static final String MESSAGE = "Remove the unused local variable \"%s\".";
+
+  @Override
+  public Set<AstNodeType> subscribedKinds() {
+    return ImmutableSet.of(PythonGrammar.FUNCDEF);
+  }
+
+  @Override
+  public void visitNode(AstNode functionTree) {
+    for (Symbol symbol : getContext().symbolTable().symbols(functionTree)) {
+      checkSymbol(symbol);
+    }
+  }
+
+  private void checkSymbol(Symbol symbol) {
+    if (symbol.readUsages().isEmpty()) {
+      for (AstNode writeUsage : symbol.writeUsages()) {
+        if (!writeUsage.hasAncestor(PythonGrammar.TYPEDARGSLIST)) {
+          addIssue(writeUsage, String.format(MESSAGE, symbol.name()));
+        }
+      }
+    }
+  }
+}
diff --git a/python-checks/src/main/resources/org/sonar/l10n/py/rules/python/S1481.html b/python-checks/src/main/resources/org/sonar/l10n/py/rules/python/S1481.html
@@ -0,0 +1,15 @@
+<p>If a local variable is declared but not used, it is dead code and should be removed. Doing so will improve maintainability because developers will
+not wonder what the variable is used for.</p>
+<h2>Noncompliant Code Example</h2>
+<pre>
+def hello(name):
+    message = "Hello " + name # Noncompliant
+    print(name)
+</pre>
+<h2>Compliant Solution</h2>
+<pre>
+def hello(name):
+    message = "Hello " + name
+    print(message)
+</pre>
+
diff --git a/python-checks/src/main/resources/org/sonar/l10n/py/rules/python/S1481.json b/python-checks/src/main/resources/org/sonar/l10n/py/rules/python/S1481.json
@@ -0,0 +1,13 @@
+{
+  "title": "Unused local variables should be removed",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "5min"
+  },
+  "tags": [
+    "unused"
+  ],
+  "defaultSeverity": "Minor"
+}
diff --git a/python-checks/src/main/resources/org/sonar/l10n/py/rules/python/Sonar_way_profile.json b/python-checks/src/main/resources/org/sonar/l10n/py/rules/python/Sonar_way_profile.json
@@ -17,6 +17,7 @@
     "S1110",
     "S1134",
     "S1313",
+    "S1481",
     "S1542",
     "S1656",
     "S1700",
diff --git a/python-checks/src/test/java/org/sonar/python/checks/UnusedLocalVariableCheckTest.java b/python-checks/src/test/java/org/sonar/python/checks/UnusedLocalVariableCheckTest.java
@@ -0,0 +1,31 @@
+/*
+ * SonarQube Python Plugin
+ * Copyright (C) 2011-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.python.checks;
+
+import org.junit.Test;
+import org.sonar.python.checks.utils.PythonCheckVerifier;
+
+public class UnusedLocalVariableCheckTest {
+
+  @Test
+  public void test() {
+    PythonCheckVerifier.verify("src/test/resources/checks/unusedLocalVariable.py", new UnusedLocalVariableCheck());
+  }
+}
diff --git a/python-checks/src/test/resources/checks/unusedLocalVariable.py b/python-checks/src/test/resources/checks/unusedLocalVariable.py
@@ -0,0 +1,12 @@
+unread_global = 1
+
+def f(unread_param):
+    global unread_global
+    unread_global = 1
+    unread_local = 1 # Noncompliant {{Remove the unused local variable "unread_local".}}
+    unread_local = 2 # Noncompliant
+    read_local = 1
+    print(read_local)
+    read_in_nested_function = 1
+    def nested_function():
+        print(read_in_nested_function)
diff --git a/sonar-python-plugin/src/test/java/org/sonar/plugins/python/PythonRuleRepositoryTest.java b/sonar-python-plugin/src/test/java/org/sonar/plugins/python/PythonRuleRepositoryTest.java
@@ -42,7 +42,7 @@ public void createRulesTest() {
 
     List<RulesDefinition.Rule> rules = repository.rules();
     assertThat(rules).isNotNull();
-    assertThat(rules).hasSize(53);
+    assertThat(rules).hasSize(54);
   }
 
 }

Original file line number	Diff line number	Diff line change
`@@ -42,7 +42,7 @@ public void createRulesTest() {`
`42`	`42`
`43`	`43`	`List<RulesDefinition.Rule> rules = repository.rules();`
`44`	`44`	`assertThat(rules).isNotNull();`
`45`		`- assertThat(rules).hasSize(53);`
	`45`	`+ assertThat(rules).hasSize(54);`
`46`	`46`	`}`
`47`	`47`
`48`	`48`	`}`