added PY-3348 Inspection to highlight occurrences of @classmethod and @staticmethod on methods outside of a class

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

@@ -87,6 +87,9 @@ QFIX.replace.function.set.with.literal=Replace function call with set literal
 #DocstringQuickFix
 QFIX.docstring=Add/remove parameters docstring parameters
 
+#RemoveDecoratorQuickFix
+QFIX.remove.decorator=Remove decorator
+
 # 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'
@@ -393,6 +396,10 @@ INSP.NAME.missing.super.constructor=Missed call to constructor of super class
 # PySetFunctionToLiteralInspection
 INSP.NAME.set.function.to.literal=Function call can be replaced with set literal
 
+# PyDecoratorInspection
+INSP.NAME.decorator.outside.class=Class specific decorator on method outside class
+
+
 # Refactoring
 # introduce
 refactoring.introduce.name.error=Incorrect name

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

@@ -0,0 +1,30 @@
+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 org.jetbrains.annotations.NotNull;
+
+/**
+ * User: catherine
+ *
+ * QuickFix to remove redundant argument equal default
+ */
+public class RemoveDecoratorQuickFix implements LocalQuickFix {
+  @NotNull
+  public String getName() {
+    return PyBundle.message("QFIX.remove.decorator");
+  }
+
+  @NotNull
+  public String getFamilyName() {
+    return PyBundle.message("INSP.GROUP.python");
+  }
+
+  public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor) {
+    PsiElement element = descriptor.getPsiElement();
+    element.delete();
+  }
+}

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

@@ -0,0 +1,56 @@
+package com.jetbrains.python.inspections;
+
+import com.intellij.codeInspection.ProblemsHolder;
+import com.intellij.psi.PsiElementVisitor;
+import com.jetbrains.python.PyBundle;
+import com.jetbrains.python.actions.RemoveDecoratorQuickFix;
+import com.jetbrains.python.psi.PyClass;
+import com.jetbrains.python.psi.PyDecorator;
+import com.jetbrains.python.psi.PyDecoratorList;
+import com.jetbrains.python.psi.PyFunction;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * User: catherine
+ *
+ * Inspection to detect occurrences of @classmethod and @staticmethod
+ * on methods outside of a class
+ */
+public class PyDecoratorInspection extends PyInspection {
+  @Nls
+  @NotNull
+  @Override
+  public String getDisplayName() {
+    return PyBundle.message("INSP.NAME.too.broad.exception.clauses");
+  }
+
+  @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 visitPyFunction(final PyFunction node){
+      PyClass containingClass = node.getContainingClass();
+      if (containingClass != null)
+        return;
+
+      PyDecoratorList decorators = node.getDecoratorList();
+      if (decorators == null)
+        return;
+      for (PyDecorator decorator : decorators.getDecorators()) {
+        String name = decorator.getText();
+        if (name.equals("@classmethod") || name.equals("@staticmethod"))
+          registerProblem(decorator, "Decorator " + name + " on method outside class", new RemoveDecoratorQuickFix());
+      }
+    }
+  }
+}

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

@@ -59,6 +59,7 @@ public class PythonInspectionToolProvider implements InspectionToolProvider {
       PyMissingConstructorInspection.class,
       PyArgumentEqualDefaultInspection.class,
       PySetFunctionToLiteralInspection.class,
+      PyDecoratorInspection.class,
     };
   }
 }

python/testData/inspections/PyDecoratorInspection/test.py

@@ -0,0 +1,8 @@
+class C:
+  @classmethod
+  def foo(self):
+    pass
+
+<warning descr="Decorator @classmethod on method outside class">@classmethod</warning>
+def foo(self):
+  print ("Constructor C was called")

python/testData/inspections/RemoveDecorator.py

@@ -0,0 +1,8 @@
+class C:
+  @classmethod
+  def foo(self):
+    pass
+
+<warning descr="Decorator @classmethod on method outside class"><caret>@classmethod</warning>
+def foo(self):
+  print ("Constructor C was called")

python/testData/inspections/RemoveDecorator_after.py

@@ -0,0 +1,7 @@
+class C:
+  @classmethod
+  def foo(self):
+    pass
+
+def foo(self):
+  print ("Constructor C was called")

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

@@ -252,6 +252,11 @@ public class PyQuickFixTest extends PyLightFixtureTestCase {
                      PyBundle.message("QFIX.remove.argument.equal.default"), true, true);
   }
 
+  public void testRemoveDecorator() {                      //PY-3348
+    doInspectionTest("RemoveDecorator.py", PyDecoratorInspection.class,
+                     PyBundle.message("QFIX.remove.decorator"), true, true);
+  }
+
   public void testSetFunctionToLiteral() {                      //PY-3120
     setLanguageLevel(LanguageLevel.PYTHON27);
     doInspectionTest("SetFunctionToLiteral.py", PySetFunctionToLiteralInspection.class,

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

@@ -344,4 +344,8 @@ public class PythonInspectionsTest extends PyLightFixtureTestCase {
     setLanguageLevel(LanguageLevel.PYTHON27);
     doHighlightingTest(PySetFunctionToLiteralInspection.class);
   }
+
+  public void testPyDecoratorInspection() {    //PY-3348
+    doHighlightingTest(PyDecoratorInspection.class);
+  }
 }