implemented W0212 pylint inspection

Access to a protected member %s of a client class

python/src/META-INF/python-plugin-common.xml

@@ -317,6 +317,7 @@
     <localInspection language="Python" shortName="PyPackageRequirementsInspection" bundle="com.jetbrains.python.PyBundle" key="INSP.NAME.requirements" groupKey="INSP.GROUP.python" enabledByDefault="true"  level="WARNING" implementationClass="com.jetbrains.python.inspections.PyPackageRequirementsInspection"/>
     <localInspection language="Python" shortName="PyPep8Inspection" displayName="PEP 8 coding style violation" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WEAK WARNING" implementationClass="com.jetbrains.python.inspections.PyPep8Inspection"/>
     <localInspection language="Python" shortName="PyAttributeOutsideInitInspection" displayName="Instance attribute defined outside _init_" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WEAK WARNING" implementationClass="com.jetbrains.python.inspections.PyAttributeOutsideInitInspection"/>
+    <localInspection language="Python" shortName="PyProtectedMemberInspection" displayName="Access to a protected member of a class" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WEAK WARNING" implementationClass="com.jetbrains.python.inspections.PyProtectedMemberInspection"/>
     <localInspection language="Python" shortName="PyDocstringTypesInspection" bundle="com.jetbrains.python.PyBundle" key="INSP.NAME.docstring.types" groupKey="INSP.GROUP.python" enabledByDefault="true"  level="WEAK WARNING" implementationClass="com.jetbrains.python.inspections.PyDocstringTypesInspection"/>
     <localInspection language="Python" shortName="PyShadowingBuiltinsInspection" displayName="Shadowing built-ins" groupKey="INSP.GROUP.python" enabledByDefault="true"  level="WARNING" implementationClass="com.jetbrains.python.inspections.PyShadowingBuiltinsInspection"/>
 

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

@@ -435,6 +435,10 @@ INSP.NAME.chained.comparisons=Chained comparisons can be simplified
 INSP.NAME.attribute.outside.init=Instance attribute defined outside _init_
 INSP.attribute.$0.outside.init=Instance attribute {0} defined outside _init_
 
+# PyProtectedMemberInspection
+INSP.NAME.protected.member.access=Access to a protected member of a class
+INSP.protected.member.$0.access=Access to a protected member {0} of a class
+
 # PyArgumentEqualDefaultInspection
 INSP.NAME.argument.equal.default=Argument passed to function is equal to default parameter value
 INSP.argument.equals.to.default=Argument equals to default parameter value

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

@@ -0,0 +1,65 @@
+package com.jetbrains.python.inspections;
+
+import com.intellij.codeInspection.LocalInspectionToolSession;
+import com.intellij.codeInspection.ProblemsHolder;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiElementVisitor;
+import com.intellij.psi.PsiReference;
+import com.intellij.psi.util.PsiTreeUtil;
+import com.jetbrains.python.PyBundle;
+import com.jetbrains.python.psi.PyClass;
+import com.jetbrains.python.psi.PyExpression;
+import com.jetbrains.python.psi.PyReferenceExpression;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * User: ktisha
+ *
+ * Inspection to detect situations, where
+ * protected member (i.e. class member with a name beginning with an underscore)
+ * is access outside the class or a descendant of the class where it's defined.
+ */
+public class PyProtectedMemberInspection extends PyInspection {
+  @Nls
+  @NotNull
+  @Override
+  public String getDisplayName() {
+    return PyBundle.message("INSP.NAME.protected.member.access");
+  }
+
+  @NotNull
+  @Override
+  public PsiElementVisitor buildVisitor(@NotNull ProblemsHolder holder,
+                                        boolean isOnTheFly,
+                                        @NotNull LocalInspectionToolSession session) {
+    return new Visitor(holder, session);
+  }
+
+
+  private static class Visitor extends PyInspectionVisitor {
+    public Visitor(@Nullable ProblemsHolder holder, @NotNull LocalInspectionToolSession session) {
+      super(holder, session);
+    }
+
+    @Override
+    public void visitPyReferenceExpression(PyReferenceExpression node) {
+      final PyExpression qualifier = node.getQualifier();
+      if (qualifier == null) return;
+      final String name = node.getName();
+      if (name != null && name.startsWith("_")) {
+        final PyClass parentClass = PsiTreeUtil.getParentOfType(node, PyClass.class);
+        if (parentClass != null) {
+          final PsiReference reference = node.getReference();
+          final PsiElement resolvedExpression = reference.resolve();
+          final PyClass resolvedClass = PsiTreeUtil.getParentOfType(resolvedExpression, PyClass.class);
+          if (parentClass.isSubclass(resolvedClass))
+            return;
+        }
+        registerProblem(node, PyBundle.message("INSP.protected.member.$0.access", name));
+      }
+    }
+
+  }
+}

python/testData/inspections/PyProtectedMemberInspection/trueNegative.py

@@ -0,0 +1,15 @@
+__author__ = 'ktisha'
+
+class A:
+  def __init__(self):
+    self._a = 1
+
+  def foo(self):
+    self.b= 1
+
+class B(A):
+  def __init__(self):
+    A.__init__(self)
+    self.b = self._a
+
+

python/testData/inspections/PyProtectedMemberInspection/truePositive.py

@@ -0,0 +1,11 @@
+__author__ = 'ktisha'
+
+class A:
+  def __init__(self):
+    self._a = 1
+
+  def foo(self):
+    self.b= 1
+
+
+print <weak_warning descr="Access to a protected member _a of a class">A()._a</weak_warning>

python/testData/inspections/PyProtectedMemberInspection/truePositiveInClass.py

@@ -0,0 +1,12 @@
+__author__ = 'ktisha'
+
+class A:
+  def __init__(self):
+    self._a = 1
+
+  def foo(self):
+    self.b= 1
+
+class B:
+  def __init__(self):
+    <weak_warning descr="Access to a protected member _a of a class">A()._a</weak_warning>

python/testSrc/com/jetbrains/python/inspections/PyProtectedMemberInspectionTest.java

@@ -0,0 +1,27 @@
+package com.jetbrains.python.inspections;
+
+import com.jetbrains.python.fixtures.PyTestCase;
+
+/**
+ * User: ktisha
+ */
+public class PyProtectedMemberInspectionTest extends PyTestCase {
+
+  public void testTruePositive() {
+    doTest();
+  }
+
+  public void testTruePositiveInClass() {
+    doTest();
+  }
+
+  public void testTrueNegative() {
+    doTest();
+  }
+
+  private void doTest() {
+    myFixture.configureByFile("inspections/PyProtectedMemberInspection/" + getTestName(true) + ".py");
+    myFixture.enableInspections(PyProtectedMemberInspection.class);
+    myFixture.checkHighlighting(false, false, true);
+  }
+}