Py-698

Inspection to check that comparisons with None are performed with 'is' rather than '=='

python/src/com/jetbrains/python/PyBundle.properties

@@ -42,6 +42,8 @@ QFIX.simplify=Simplify
 
 QFIX.move.from.future.import=Move 'from __future__ import' to a correct place
 
+QFIX.replace.equality=Replace equality
+
 # Intentions: INTN
 INTN.Family.convert.import.unqualify=Convert 'import module' to 'from module import'
 INTN.Family.convert.import.qualify=Convert 'from module import' to 'import module'
@@ -210,6 +212,9 @@ INSP.expression.can.be.simplified=Expression can be simplified
 # PyFromFutureImportInspection
 INSP.NAME.from.future.import=from __future__ import must be the first executable statement
 
+# PyComparisonWithNoneInspection
+INSP.NAME.comparison.with.none=Comparison with None performed with equality operators
+
 # Refactoring
 # introduce
 refactoring.introduce.name.error=Incorrect name

python/src/com/jetbrains/python/actions/ComparisonWithNoneQuickFix.java

@@ -0,0 +1,47 @@
+package com.jetbrains.python.actions;
+
+import com.intellij.codeInspection.LocalQuickFix;
+import com.intellij.codeInspection.ProblemDescriptor;
+import com.intellij.openapi.project.Project;
+import com.intellij.psi.PsiElement;
+import com.jetbrains.python.PyBundle;
+import com.jetbrains.python.PyTokenTypes;
+import com.jetbrains.python.PythonLanguage;
+import com.jetbrains.python.psi.PyBinaryExpression;
+import com.jetbrains.python.psi.PyElementGenerator;
+import com.jetbrains.python.psi.PyElementType;
+import com.jetbrains.python.psi.PyExpression;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Created by IntelliJ IDEA.
+ * Author: Alexey.Ivanov
+ * Date:   24.03.2010
+ * Time:   22:00:49
+ */
+public class ComparisonWithNoneQuickFix implements LocalQuickFix {
+  @NotNull
+  public String getName() {
+    return PyBundle.message("QFIX.replace.equality");
+  }
+
+  @NotNull
+  public String getFamilyName() {
+    return PyBundle.message("INSP.GROUP.python");
+  }
+
+  public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor) {
+    PsiElement problemElement = descriptor.getPsiElement();
+    if (problemElement instanceof PyBinaryExpression) {
+      PyBinaryExpression binaryExpression = (PyBinaryExpression)problemElement;
+      PyElementType operator = binaryExpression.getOperator();
+      PyElementGenerator elementGenerator = PythonLanguage.getInstance().getElementGenerator();
+      String temp;
+      temp = (operator == PyTokenTypes.EQEQ) ? "is" : "is not";
+      PyExpression expression = elementGenerator.createBinaryExpression(project, temp,
+                                                                        binaryExpression.getLeftExpression(),
+                                                                        binaryExpression.getRightExpression());
+      binaryExpression.replace(expression);
+    }
+  }
+}

python/src/com/jetbrains/python/inspections/PyComparisonWithNoneInspection.java

@@ -0,0 +1,74 @@
+package com.jetbrains.python.inspections;
+
+import com.intellij.codeInspection.LocalInspectionTool;
+import com.intellij.codeInspection.ProblemsHolder;
+import com.intellij.psi.PsiElementVisitor;
+import com.jetbrains.python.PyBundle;
+import com.jetbrains.python.PyNames;
+import com.jetbrains.python.PyTokenTypes;
+import com.jetbrains.python.actions.ComparisonWithNoneQuickFix;
+import com.jetbrains.python.psi.PyBinaryExpression;
+import com.jetbrains.python.psi.PyElementType;
+import com.jetbrains.python.psi.PyExpression;
+import com.jetbrains.python.psi.PyReferenceExpression;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Created by IntelliJ IDEA.
+ * Author: Alexey.Ivanov
+ * Date:   24.03.2010
+ * Time:   21:33:51
+ */
+public class PyComparisonWithNoneInspection extends LocalInspectionTool {
+  @Nls
+  @NotNull
+  @Override
+  public String getGroupDisplayName() {
+    return PyBundle.message("INSP.GROUP.python");
+  }
+
+  @Nls
+  @NotNull
+  @Override
+  public String getDisplayName() {
+    return PyBundle.message("INSP.NAME.comparison.with.none");
+  }
+
+  @NotNull
+  @Override
+  public String getShortName() {
+    return "PyComparisonWithNoneInspection";
+  }
+
+  @Override
+  public boolean isEnabledByDefault() {
+    return true;
+  }
+
+  @NotNull
+  @Override
+  public PsiElementVisitor buildVisitor(@NotNull ProblemsHolder holder, boolean isOnTheFly) {
+    return new Visitor(holder);
+  }
+
+  private static class Visitor extends PyInspectionVisitor {
+
+    public Visitor(final ProblemsHolder holder) {
+      super(holder);
+    }
+
+    @Override
+    public void visitPyBinaryExpression(PyBinaryExpression node) {
+      final PyExpression rightExpression = node.getRightExpression();
+      if (rightExpression instanceof PyReferenceExpression) {
+        if (PyNames.NONE.equals(rightExpression.getName())) {
+          final PyElementType operator = node.getOperator();
+          if (operator == PyTokenTypes.EQEQ || operator == PyTokenTypes.NE || operator == PyTokenTypes.NE_OLD) {
+            registerProblem(node, "Comparison with None performed with equality operators", new ComparisonWithNoneQuickFix());
+          }
+        }
+      }
+    }
+  }
+}

python/src/com/jetbrains/python/inspections/PythonInspectionToolProvider.java

@@ -33,7 +33,8 @@ public class PythonInspectionToolProvider implements InspectionToolProvider {
       PyUnboundLocalVariableInspection.class,
       PyStatementEffectInspection.class,
       PySimplifyBooleanCheckInspection.class,
-      PyFromFutureImportInspection.class
+      PyFromFutureImportInspection.class,
+      PyComparisonWithNoneInspection.class
     };
   }
 }

python/testData/inspections/ComparisonWithNone.py

@@ -0,0 +1,2 @@
+if <warning descr="Comparison with None performed with equality operators"><caret>a != None</warning>:
+  pass

python/testData/inspections/ComparisonWithNone_after.py

@@ -0,0 +1,2 @@
+if a is not None:
+  pass

python/testData/inspections/PyComparisonWithNoneInspection/expected.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>test.py</file>
+    <line>1</line>
+    <description>Comparison with None performed with equality operators</description>
+  </problem>
+  <problem>
+    <file>test.py</file>
+    <line>1</line>
+    <description>Comparison with None performed with equality operators</description>
+  </problem>
+  <problem>
+    <file>test.py</file>
+    <line>1</line>
+    <description>Comparison with None performed with equality operators</description>
+  </problem>
+</problems>

python/testData/inspections/PyComparisonWithNoneInspection/src/test.py

@@ -0,0 +1,5 @@
+if a <> None and b != None and c == None:
+  pass
+
+if a is None and b is not None:
+  pass

python/testSrc/com/jetbrains/python/PyQuickFixTest.java

@@ -115,6 +115,11 @@ public class PyQuickFixTest extends PyLightFixtureTestCase {
                      PyBundle.message("QFIX.move.from.future.import"), true, true);
   }
 
+  public void testComparisonWithNoneQuickFix() throws Exception {
+    doInspectionTest("ComparisonWithNone.py", PyComparisonWithNoneInspection.class,
+                     PyBundle.message("QFIX.replace.equality"), true, true);
+  }
+
   @NonNls
   protected String getTestDataPath() {
     return PythonTestUtil.getTestDataPath() + "/inspections/";

python/testSrc/com/jetbrains/python/PythonInspectionsTest.java

@@ -155,4 +155,9 @@ public class PythonInspectionsTest extends PyLightFixtureTestCase {
     LocalInspectionTool inspection = new PyFromFutureImportInspection();
     doTest(getTestName(false), inspection);
   }
+
+  public void testPyComparisonWithNoneInspection() throws Throwable {
+    LocalInspectionTool inspection = new PyComparisonWithNoneInspection();
+    doTest(getTestName(false), inspection);
+  }
 }