Python docstring inspection

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

@@ -181,6 +181,9 @@ INSP.NAME.default.argument=Default argument is mutable
 # PyRaisingNewStyleClassInspection
 INSP.NAME.raising.new.style.class=Raising a new style class
 
+# PyDocstringInspection
+INSP.NAME.docstring=Missing or empty docstring
+
 # Refactoring
 # introduce
 refactoring.introduce.name.error=Incorrect name

python/src/com/jetbrains/python/inspections/PyDocstringInspection.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.psi.*;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Created by IntelliJ IDEA.
+ * Author: Alexey.Ivanov
+ * Date:   10.03.2010
+ * Time:   16:14:45
+ */
+public class PyDocstringInspection 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.docstring");
+  }
+
+  @NotNull
+  @Override
+  public String getShortName() {
+    return "PyDocstringInspection";
+  }
+
+  @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 visitPyFile(PyFile node) {
+      checkDocString(node);
+    }
+
+    @Override
+    public void visitPyFunction(PyFunction node) {
+      checkDocString(node);
+    }
+
+    @Override
+    public void visitPyClass(PyClass node) {
+      checkDocString(node);
+    }
+
+    private void checkDocString(PyDocStringOwner node) {
+      PyStringLiteralExpression docStringExpression = node.getDocStringExpression();
+      if (docStringExpression == null) {
+        registerProblem(node, "Missing docstring"); // node?
+      } else if ("".equals(docStringExpression.getStringValue().trim())) {
+        registerProblem(docStringExpression, "Empty docstring");
+      }
+    }
+  }
+}

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

@@ -30,6 +30,7 @@ public class PythonInspectionToolProvider implements InspectionToolProvider {
       PyDefaultArgumentInspection.class,
       PyRaisingNewStyleClassInspection.class,
       PyUnboundLocalVariableInspection.class,
+      PyDocstringInspection.class
     };
   }
 }

python/testData/inspections/PyDocstringInspection/expected.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>test.py</file>
+    <line>1</line>
+    <description>Missing docstring</description>
+  </problem>
+  <problem>
+    <file>test.py</file>
+    <line>1</line>
+    <description>Missing docstring</description>
+  </problem>
+  <problem>
+    <file>test.py</file>
+    <line>4</line>
+    <description>Missing docstring</description>
+  </problem>
+  <problem>
+    <file>test.py</file>
+    <line>9</line>
+    <description>Empty docstring</description>
+  </problem>
+  <problem>
+    <file>test.py</file>
+    <line>13</line>
+    <description>Empty docstring</description>
+  </problem>
+</problems>

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

@@ -0,0 +1,14 @@
+class A:
+    pass
+
+def foo():
+  pass
+
+
+class B:
+    """"""
+    pass
+
+def bar():
+  """"""
+  pass

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

@@ -137,4 +137,9 @@ public class PythonInspectionsTest extends PyLightFixtureTestCase {
     LocalInspectionTool inspection = new PyUnboundLocalVariableInspection();
     doTest(getTestName(false), inspection);
   }
+  
+  public void testPyDocstringInspection() throws Throwable {
+    LocalInspectionTool inspection = new PyDocstringInspection();
+    doTest(getTestName(false), inspection);
+  }
 }