inspection highlights deprecated members

python/src/com/jetbrains/python/PyNames.java

@@ -12,54 +12,59 @@ import java.util.regex.Pattern;
 /**
  * @author dcheryasov
  */
+@NonNls
 public class PyNames {
   private PyNames() {
   }
 
-  @NonNls public static final String INIT = "__init__";
-  @NonNls public static final String DOT_PY = ".py";
-  @NonNls public static final String INIT_DOT_PY = INIT + DOT_PY;
+  public static final String INIT = "__init__";
+  public static final String DOT_PY = ".py";
+  public static final String INIT_DOT_PY = INIT + DOT_PY;
 
-  @NonNls public static final String NEW = "__new__";
-  @NonNls public static final String GETATTR = "__getattr__";
-  @NonNls public static final String GETATTRIBUTE = "__getattribute__";
-  @NonNls public static final String CLASS = "__class__";
-  @NonNls public static final String METACLASS = "__metaclass__";
+  public static final String NEW = "__new__";
+  public static final String GETATTR = "__getattr__";
+  public static final String GETATTRIBUTE = "__getattribute__";
+  public static final String CLASS = "__class__";
+  public static final String METACLASS = "__metaclass__";
 
-  @NonNls public static final String SUPER = "super";
+  public static final String SUPER = "super";
 
-  @NonNls public static final String OBJECT = "object";
-  @NonNls public static final String NONE = "None";
-  @NonNls public static final String TRUE = "True";
-  @NonNls public static final String FALSE = "False";
-  @NonNls public static final String FAKE_OLD_BASE = "___Classobj";
+  public static final String OBJECT = "object";
+  public static final String NONE = "None";
+  public static final String TRUE = "True";
+  public static final String FALSE = "False";
+  public static final String FAKE_OLD_BASE = "___Classobj";
 
-  @NonNls public static final String FUTURE_MODULE = "__future__";
+  public static final String FUTURE_MODULE = "__future__";
 
-  @NonNls public static final String CLASSMETHOD = "classmethod";
-  @NonNls public static final String STATICMETHOD = "staticmethod";
+  public static final String CLASSMETHOD = "classmethod";
+  public static final String STATICMETHOD = "staticmethod";
 
-  @NonNls public static final String PROPERTY = "property";
+  public static final String PROPERTY = "property";
 
-  @NonNls public static final String ALL = "__all__";
-  @NonNls public static final String SLOTS = "__slots__";
-  @NonNls public static final String DEBUG = "__debug__";
+  public static final String ALL = "__all__";
+  public static final String SLOTS = "__slots__";
+  public static final String DEBUG = "__debug__";
 
-  @NonNls public static final String ISINSTANCE = "isinstance";
+  public static final String ISINSTANCE = "isinstance";
 
-  @NonNls public static final String DOCFORMAT = "__docformat__";
+  public static final String DOCFORMAT = "__docformat__";
 
-  @NonNls public static final String DIRNAME = "dirname";
-  @NonNls public static final String ABSPATH = "abspath";
-  @NonNls public static final String JOIN = "join";
-  @NonNls public static final String REPLACE = "replace";
-  @NonNls public static final String FILE = "__file__";
+  public static final String DIRNAME = "dirname";
+  public static final String ABSPATH = "abspath";
+  public static final String JOIN = "join";
+  public static final String REPLACE = "replace";
+  public static final String FILE = "__file__";
+
+  public static final String WARN = "warn";
+  public static final String DEPRECATION_WARNING = "DeprecationWarning";
+  public static final String PENDING_DEPRECATION_WARNING = "PendingDeprecationWarning";
 
   /**
    * Contains all known predefined names of "__foo__" form.
    */
   public static ImmutableSet<String> UnderscoredAttributes = ImmutableSet.of(
-    "__all__",
+      "__all__",
     "__author__",
     "__bases__",
     "__dict__",

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

@@ -0,0 +1,57 @@
+package com.jetbrains.python.inspections;
+
+import com.intellij.codeInspection.LocalInspectionToolSession;
+import com.intellij.codeInspection.ProblemHighlightType;
+import com.intellij.codeInspection.ProblemsHolder;
+import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiElementVisitor;
+import com.jetbrains.python.psi.PyFile;
+import com.jetbrains.python.psi.PyFunction;
+import com.jetbrains.python.psi.PyReferenceExpression;
+import com.jetbrains.python.psi.resolve.PyResolveContext;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * @author yole
+ */
+public class PyDeprecationInspection extends PyInspection {
+  @Nls
+  @NotNull
+  @Override
+  public String getDisplayName() {
+    return "Deprecated function, class or module";
+  }
+
+  @NotNull
+  @Override
+  public PsiElementVisitor buildVisitor(@NotNull ProblemsHolder holder,
+                                        boolean isOnTheFly,
+                                        @NotNull LocalInspectionToolSession session) {
+    return new Visitor(holder);
+  }
+
+  private static class Visitor extends PyInspectionVisitor {
+    public Visitor(@Nullable final ProblemsHolder holder) {
+      super(holder);
+    }
+
+    @Override
+    public void visitPyReferenceExpression(PyReferenceExpression node) {
+      PsiElement resolveResult = node.getReference(PyResolveContext.noImplicits()).resolve();
+      String deprecationMessage = null;
+      if (resolveResult instanceof PyFunction) {
+        deprecationMessage = ((PyFunction) resolveResult).getDeprecationMessage();
+      }
+      else if (resolveResult instanceof PyFile) {
+        deprecationMessage = ((PyFile)resolveResult).getDeprecationMessage();
+      }
+      if (deprecationMessage != null) {
+        ASTNode nameElement = node.getNameElement();
+        registerProblem(nameElement == null ? node : nameElement.getPsi(), deprecationMessage, ProblemHighlightType.LIKE_DEPRECATED, null);
+      }
+    }
+  }
+}

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

@@ -61,6 +61,7 @@ public class PythonInspectionToolProvider implements InspectionToolProvider {
       PySetFunctionToLiteralInspection.class,
       PyDecoratorInspection.class,
       PyTypeCheckerInspection.class,
+      PyDeprecationInspection.class,
     };
   }
 }

python/src/com/jetbrains/python/psi/PyFile.java

@@ -1,6 +1,5 @@
 package com.jetbrains.python.psi;
 
-import com.intellij.openapi.util.Key;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.jetbrains.python.codeInsight.controlflow.ScopeOwner;
@@ -62,4 +61,11 @@ public interface PyFile extends PyElement, PsiFile, PyDocStringOwner, ScopeOwner
    * Return true if the file contains a 'from __future__ import ...' statement with given feature.
    */
   boolean hasImportFromFuture(FutureFeature feature);
+
+  /**
+   * If the function raises a DeprecationWarning or a PendingDeprecationWarning, returns the explanation text provided for the warning..
+   *
+   * @return the deprecation message or null if the function is not deprecated.
+   */
+  String getDeprecationMessage();
 }

python/src/com/jetbrains/python/psi/PyFileElementType.java

@@ -14,6 +14,7 @@ import com.intellij.psi.stubs.StubElement;
 import com.intellij.psi.stubs.StubInputStream;
 import com.intellij.psi.stubs.StubOutputStream;
 import com.intellij.psi.tree.IStubFileElementType;
+import com.intellij.util.io.StringRef;
 import com.jetbrains.python.lexer.PythonIndentingLexer;
 import com.jetbrains.python.parsing.PyParser;
 import com.jetbrains.python.parsing.StatementParsing;
@@ -42,7 +43,7 @@ public class PyFileElementType extends IStubFileElementType<PyFileStub> {
 
   @Override
   public int getStubVersion() {
-    return 33;
+    return 34;
   }
 
   @Override
@@ -84,13 +85,15 @@ public class PyFileElementType extends IStubFileElementType<PyFileStub> {
   public void serialize(PyFileStub stub, StubOutputStream dataStream) throws IOException {
     writeNullableList(dataStream, stub.getDunderAll());
     writeBitSet(dataStream, stub.getFutureFeatures());
+    dataStream.writeName(stub.getDeprecationMessage());
   }
 
   @Override
   public PyFileStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
     List<String> all = readNullableList(dataStream);
     BitSet future_features = readBitSet(dataStream);
-    return new PyFileStubImpl(all, future_features);
+    StringRef deprecationMessage = dataStream.readName();
+    return new PyFileStubImpl(all, future_features, deprecationMessage);
   }
 
   private static BitSet readBitSet(StubInputStream dataStream) throws IOException {

python/src/com/jetbrains/python/psi/PyFunction.java

@@ -53,6 +53,13 @@ extends
   @Nullable
   PyType getReturnTypeFromDocString();
 
+  /**
+   * If the function raises a DeprecationWarning or a PendingDeprecationWarning, returns the explanation text provided for the warning..
+   *
+   * @return the deprecation message or null if the function is not deprecated.
+   */
+  String getDeprecationMessage();
+
   /**
    * Flags that mark common alterations of a function: decoration by and wrapping in classmethod() and staticmethod().
    */

python/src/com/jetbrains/python/psi/impl/PyCallExpressionImpl.java

@@ -51,7 +51,7 @@ public class PyCallExpressionImpl extends PyElementImpl implements PyCallExpress
   @Override
   public <T extends PsiElement> T getArgument(int index, Class<T> argClass) {
     PyExpression[] args = getArguments();
-    return args.length >= index && argClass.isInstance(args[index]) ? argClass.cast(args[index]) : null;
+    return args.length > index && argClass.isInstance(args[index]) ? argClass.cast(args[index]) : null;
   }
 
   public void addArgument(PyExpression expression) {

python/src/com/jetbrains/python/psi/impl/PyFileImpl.java

@@ -547,6 +547,19 @@ public class PyFileImpl extends PsiFileBase implements PyFile, PyExpression {
     return enabled;
   }
 
+  @Override
+  public String getDeprecationMessage() {
+    final StubElement stub = getStub();
+    if (stub instanceof PyFileStub) {
+      return ((PyFileStub) stub).getDeprecationMessage();
+    }
+    return extractDeprecationMessage();
+  }
+
+  public String extractDeprecationMessage() {
+    return PyFunctionImpl.extractDeprecationMessage(getStatements());
+  }
+
   public boolean calculateImportFromFuture(FutureFeature feature) {
     final List<PyFromImportStatement> fromImports = getFromImports();
     for (PyFromImportStatement fromImport : fromImports) {

python/src/com/jetbrains/python/psi/impl/PyFunctionImpl.java

@@ -220,6 +220,42 @@ public class PyFunctionImpl extends PyPresentableElementImpl<PyFunctionStub> imp
     return PyTypeParser.getTypeByName(this, typeName);
   }
 
+  @Override
+  public String getDeprecationMessage() {
+    PyFunctionStub stub = getStub();
+    if (stub != null) {
+      return stub.getDeprecationMessage();
+    }
+    return extractDeprecationMessage();
+  }
+
+  public String extractDeprecationMessage() {
+    PyStatementList statementList = getStatementList();
+    if (statementList == null) {
+      return null;
+    }
+    return extractDeprecationMessage(Arrays.asList(statementList.getStatements()));
+  }
+
+  public static String extractDeprecationMessage(List<PyStatement> statements) {
+    for (PyStatement statement : statements) {
+      if (statement instanceof PyExpressionStatement) {
+        PyExpressionStatement expressionStatement = (PyExpressionStatement)statement;
+        if (expressionStatement.getExpression() instanceof PyCallExpression) {
+          PyCallExpression callExpression = (PyCallExpression)expressionStatement.getExpression();
+          if (callExpression.isCalleeText(PyNames.WARN)) {
+            PyReferenceExpression warningClass = callExpression.getArgument(1, PyReferenceExpression.class);
+            if (warningClass != null && (PyNames.DEPRECATION_WARNING.equals(warningClass.getReferencedName()) ||
+                                         PyNames.PENDING_DEPRECATION_WARNING.equals(warningClass.getReferencedName()))) {
+              return PyUtil.strValue(callExpression.getArguments() [0]);
+            }
+          }
+        }
+      }
+    }
+    return null;
+  }
+
   @Nullable
   public String extractDocStringReturnType() {
     final PyStringLiteralExpression docString = getDocStringExpression();

python/src/com/jetbrains/python/psi/impl/stubs/PyFileStubImpl.java

@@ -2,6 +2,7 @@ package com.jetbrains.python.psi.impl.stubs;
 
 import com.intellij.psi.stubs.PsiFileStubImpl;
 import com.intellij.psi.tree.IStubFileElementType;
+import com.intellij.util.io.StringRef;
 import com.jetbrains.python.PythonLanguage;
 import com.jetbrains.python.psi.FutureFeature;
 import com.jetbrains.python.psi.PyFile;
@@ -17,6 +18,7 @@ import java.util.List;
 public class PyFileStubImpl extends PsiFileStubImpl<PyFile> implements PyFileStub {
   private final List<String> myDunderAll;
   private final BitSet myFutureFeatures; // stores IDs of features
+  private final StringRef myDeprecationMessage;
 
   private static final int FUTURE_FEATURE_SET_SIZE = 32; // 32 features is ought to be enough for everybody! all bits fit into an int.
 
@@ -28,12 +30,15 @@ public class PyFileStubImpl extends PsiFileStubImpl<PyFile> implements PyFileStu
     for (FutureFeature fuf : FutureFeature.ALL) {
       myFutureFeatures.set(fuf.ordinal(), fileImpl.calculateImportFromFuture(fuf));
     }
+    String message = fileImpl.extractDeprecationMessage();
+    myDeprecationMessage = message == null ? null : StringRef.fromString(message);
   }
 
-  public PyFileStubImpl(List<String> dunderAll, final BitSet future_features) {
+  public PyFileStubImpl(List<String> dunderAll, final BitSet future_features, final StringRef deprecationMessage) {
     super(null);
     myDunderAll = dunderAll;
     myFutureFeatures = future_features;
+    myDeprecationMessage = deprecationMessage;
   }
 
   @Override
@@ -46,6 +51,11 @@ public class PyFileStubImpl extends PsiFileStubImpl<PyFile> implements PyFileStu
     return myFutureFeatures;
   }
 
+  @Override
+  public String getDeprecationMessage() {
+    return myDeprecationMessage == null ? null : myDeprecationMessage.getString();
+  }
+
   @Override
   public IStubFileElementType getType() {
     return PythonLanguage.getInstance().getFileElementType();

python/src/com/jetbrains/python/psi/impl/stubs/PyFunctionElementType.java

@@ -32,19 +32,24 @@ public class PyFunctionElementType extends PyStubElementType<PyFunctionStub, PyF
   }
 
   public PyFunctionStub createStub(final PyFunction psi, final StubElement parentStub) {
-    return new PyFunctionStubImpl(psi.getName(), ((PyFunctionImpl) psi).extractDocStringReturnType(), parentStub);
+    PyFunctionImpl function = (PyFunctionImpl)psi;
+    String message = function.extractDeprecationMessage();
+    return new PyFunctionStubImpl(psi.getName(), function.extractDocStringReturnType(),
+                                  message == null ? null : StringRef.fromString(message), parentStub);
   }
 
   public void serialize(final PyFunctionStub stub, final StubOutputStream dataStream)
       throws IOException {
     dataStream.writeName(stub.getName());
     dataStream.writeName(stub.getReturnTypeFromDocString());
+    dataStream.writeName(stub.getDeprecationMessage());
   }
 
   public PyFunctionStub deserialize(final StubInputStream dataStream, final StubElement parentStub) throws IOException {
     String name = StringRef.toString(dataStream.readName());
     StringRef returnType = dataStream.readName();
-    return new PyFunctionStubImpl(name, returnType != null ? returnType.getString() : null, parentStub);
+    StringRef deprecationMessage = dataStream.readName();
+    return new PyFunctionStubImpl(name, returnType != null ? returnType.getString() : null, deprecationMessage, parentStub);
   }
 
   public void indexStub(final PyFunctionStub stub, final IndexSink sink) {

python/src/com/jetbrains/python/psi/impl/stubs/PyFunctionStubImpl.java

@@ -1,22 +1,24 @@
-/*
- * @author max
- */
 package com.jetbrains.python.psi.impl.stubs;
 
 import com.intellij.psi.stubs.StubBase;
 import com.intellij.psi.stubs.StubElement;
+import com.intellij.util.io.StringRef;
 import com.jetbrains.python.PyElementTypes;
 import com.jetbrains.python.psi.PyFunction;
 import com.jetbrains.python.psi.stubs.PyFunctionStub;
+import org.jetbrains.annotations.Nullable;
 
 public class PyFunctionStubImpl extends StubBase<PyFunction> implements PyFunctionStub {
   private final String myName;
   private final String myReturnTypeFromDocString;
+  private final StringRef myDeprecationMessage;
 
-  public PyFunctionStubImpl(final String name, final String returnTypeFromDocString, final StubElement parent) {
+  public PyFunctionStubImpl(final String name, final String returnTypeFromDocString, @Nullable final StringRef deprecationMessage,
+                            final StubElement parent) {
     super(parent, PyElementTypes.FUNCTION_DECLARATION);
     myName = name;
     myReturnTypeFromDocString = returnTypeFromDocString;
+    myDeprecationMessage = deprecationMessage;
   }
 
   public String getName() {
@@ -27,6 +29,11 @@ public class PyFunctionStubImpl extends StubBase<PyFunction> implements PyFuncti
     return myReturnTypeFromDocString;
   }
 
+  @Override
+  public String getDeprecationMessage() {
+    return myDeprecationMessage == null ? null : myDeprecationMessage.getString();
+  }
+
   @Override
   public String toString() {
     return "PyFunctionStub(" + myName + ")";

python/src/com/jetbrains/python/psi/stubs/PyFileStub.java

@@ -1,7 +1,6 @@
 package com.jetbrains.python.psi.stubs;
 
 import com.intellij.psi.stubs.PsiFileStub;
-import com.jetbrains.python.psi.FutureFeature;
 import com.jetbrains.python.psi.PyFile;
 
 import java.util.BitSet;
@@ -13,4 +12,5 @@ import java.util.List;
 public interface PyFileStub extends PsiFileStub<PyFile> {
   List<String> getDunderAll();
   BitSet getFutureFeatures();
+  String getDeprecationMessage();
 }

python/src/com/jetbrains/python/psi/stubs/PyFunctionStub.java

@@ -1,6 +1,3 @@
-/*
- * @author max
- */
 package com.jetbrains.python.psi.stubs;
 
 import com.intellij.psi.stubs.NamedStub;
@@ -8,4 +5,5 @@ import com.jetbrains.python.psi.PyFunction;
 
 public interface PyFunctionStub extends NamedStub<PyFunction> {
   String getReturnTypeFromDocString();
+  String getDeprecationMessage();
 }

python/testData/deprecation/deprecatedImport.py

@@ -0,0 +1 @@
+import <warning descr="the deprecated module is deprecated; use a non-deprecated module instead">deprecatedModule</warning>

python/testData/deprecation/deprecatedModule.py

@@ -0,0 +1,3 @@
+import warnings
+warnings.warn("the deprecated module is deprecated; use a non-deprecated module instead",
+                DeprecationWarning, 2)

python/testData/deprecation/deprecatedProperty.py

@@ -0,0 +1,8 @@
+class Foo:
+    @property
+    def bar(self):
+        import warnings
+        warnings.warn("this is deprecated", DeprecationWarning, 2)
+
+foo = Foo()
+foo.<warning descr="this is deprecated">bar</warning>

python/testData/deprecation/functionStub.py

@@ -0,0 +1,5 @@
+def getstatus(file):
+    """Return output of "ls -ld <file>" in a string."""
+    import warnings
+    warnings.warn("commands.getstatus() is deprecated", DeprecationWarning, 2)
+    return getoutput('ls -ld' + mkarg(file))

python/testSrc/com/jetbrains/python/PyDeprecationTest.java

@@ -0,0 +1,47 @@
+package com.jetbrains.python;
+
+import com.jetbrains.python.fixtures.PyLightFixtureTestCase;
+import com.jetbrains.python.inspections.PyDeprecationInspection;
+import com.jetbrains.python.psi.PyFile;
+import com.jetbrains.python.psi.PyFunction;
+
+/**
+ * @author yole
+ */
+public class PyDeprecationTest extends PyLightFixtureTestCase {
+  public void testFunction() {
+    myFixture.configureByText(PythonFileType.INSTANCE,
+                              "def getstatus(file):\n" +
+                              "    \"\"\"Return output of \"ls -ld <file>\" in a string.\"\"\"\n" +
+                              "    import warnings\n" +
+                              "    warnings.warn(\"commands.getstatus() is deprecated\", DeprecationWarning, 2)\n" +
+                              "    return getoutput('ls -ld' + mkarg(file))");
+    PyFunction getstatus = ((PyFile) myFixture.getFile()).findTopLevelFunction("getstatus");
+    assertEquals("commands.getstatus() is deprecated", getstatus.getDeprecationMessage());
+  }
+
+  public void testFunctionStub() {
+    myFixture.configureByFile("deprecation/functionStub.py");
+    PyFunction getstatus = ((PyFile) myFixture.getFile()).findTopLevelFunction("getstatus");
+    assertEquals("commands.getstatus() is deprecated", getstatus.getDeprecationMessage());
+    assertNotParsed((PyFile) myFixture.getFile());
+  }
+
+  public void testDeprecatedProperty() {
+    myFixture.enableInspections(PyDeprecationInspection.class);
+    myFixture.configureByFile("deprecation/deprecatedProperty.py");
+    myFixture.checkHighlighting(true, false, false);
+  }
+
+  public void testDeprecatedImport() {
+    myFixture.enableInspections(PyDeprecationInspection.class);
+    myFixture.configureByFiles("deprecation/deprecatedImport.py", "deprecation/deprecatedModule.py");
+    myFixture.checkHighlighting(true, false, false);
+  }
+
+  public void testFileStub() {
+    myFixture.configureByFile("deprecation/deprecatedModule.py");
+    assertEquals("the deprecated module is deprecated; use a non-deprecated module instead", ((PyFile) myFixture.getFile()).getDeprecationMessage());
+    assertNotParsed((PyFile) myFixture.getFile());
+  }
+}

python/testSrc/com/jetbrains/python/PyStubsTest.java

@@ -28,17 +28,12 @@ import java.util.List;
 
 @TestDataPath("$CONTENT_ROOT/../testData/stubs/")
 public class PyStubsTest extends PyLightFixtureTestCase {
-  private static final String PARSED_ERROR_MSG = "Operations should have been performed on stubs but caused file to be parsed";
 
   @Override
   protected String getTestDataPath() {
     return PythonTestUtil.getTestDataPath() + "/stubs/";
   }
 
-  private static void assertNotParsed(PyFile file) {
-    assertNull(PARSED_ERROR_MSG, ((PyFileImpl)file).getTreeElement());
-  }
-
   public void testStubStructure() {
     final PyFile file = getTestFile();
     // vfile is problematic, but we need an SDK to check builtins

python/testSrc/com/jetbrains/python/PythonAllTestsSuite.java

@@ -80,7 +80,8 @@ public class PythonAllTestsSuite {
     PyCompletionPatternsTest.class,
     PyCompatibilityInspectionTest.class,
     PyUnresolvedReferencesInspectionTest.class,
-    PyUnusedImportTest.class
+    PyUnusedImportTest.class,
+    PyDeprecationTest.class
   };
 
   public static TestSuite suite() {

python/testSrc/com/jetbrains/python/fixtures/PyLightFixtureTestCase.java

@@ -24,6 +24,8 @@ import com.intellij.testFramework.fixtures.impl.LightTempDirTestFixtureImpl;
 import com.jetbrains.python.PythonMockSdk;
 import com.jetbrains.python.PythonTestUtil;
 import com.jetbrains.python.psi.LanguageLevel;
+import com.jetbrains.python.psi.PyFile;
+import com.jetbrains.python.psi.impl.PyFileImpl;
 import com.jetbrains.python.psi.impl.PythonLanguageLevelPusher;
 import org.jetbrains.annotations.Nullable;
 
@@ -34,6 +36,7 @@ import org.jetbrains.annotations.Nullable;
 public abstract class PyLightFixtureTestCase extends UsefulTestCase {
   private static final PyLightProjectDescriptor ourPyDescriptor = new PyLightProjectDescriptor("2.5");
   protected static final PyLightProjectDescriptor ourPy3Descriptor = new PyLightProjectDescriptor("3.1");
+  private static final String PARSED_ERROR_MSG = "Operations should have been performed on stubs but caused file to be parsed";
 
   protected CodeInsightTestFixture myFixture;
   private static boolean ourPlatformPrefixInitialized;
@@ -86,6 +89,10 @@ public abstract class PyLightFixtureTestCase extends UsefulTestCase {
     PythonLanguageLevelPusher.setForcedLanguageLevel(myFixture.getProject(), languageLevel);
   }
 
+  protected static void assertNotParsed(PyFile file) {
+    assertNull(PARSED_ERROR_MSG, ((PyFileImpl)file).getTreeElement());
+  }
+
   protected static class PyLightProjectDescriptor implements LightProjectDescriptor {
     private final String myPythonVersion;