implemented pylint E1111

Inspection is used when an assignment is done on a function call but the inferred function doesn't return anything.

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

@@ -318,6 +318,7 @@
     <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="PyClassHasNoInitInspection" displayName="Class has no __init__ method" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WEAK WARNING" implementationClass="com.jetbrains.python.inspections.PyClassHasNoInitInspection"/>
+    <localInspection language="Python" shortName="PyNoneFunctionAssignmentInspection" displayName="Assigning function call that doesn't return anything" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WEAK WARNING" implementationClass="com.jetbrains.python.inspections.PyNoneFunctionAssignmentInspection"/>
     <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

@@ -476,6 +476,9 @@ INSP.NAME.class.has.no.init=Class has no __init__ method
 INSP.class.has.no.init=Class has no __init__ method
 INSP.parent.$0.has.no.init=Parent {0} has no __init__ method
 
+#PyNoneFunctionAssignmentInspection
+INSP.NAME.none.function.assignment=Assigning function call that doesn't return anything (None)
+INSP.none.function.assignment=Function {0} doesn''t return anything
 
 # Refactoring
 # introduce

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

@@ -0,0 +1,57 @@
+package com.jetbrains.python.inspections;
+
+import com.intellij.codeInspection.LocalInspectionToolSession;
+import com.intellij.codeInspection.ProblemsHolder;
+import com.intellij.psi.PsiElementVisitor;
+import com.jetbrains.python.PyBundle;
+import com.jetbrains.python.psi.PyAssignmentStatement;
+import com.jetbrains.python.psi.PyCallExpression;
+import com.jetbrains.python.psi.PyExpression;
+import com.jetbrains.python.psi.types.PyNoneType;
+import com.jetbrains.python.psi.types.PyType;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * User: ktisha
+ *
+ * pylint E1111
+ *
+ * Used when an assignment is done on a function call but the inferred function doesn't return anything.
+ */
+public class PyNoneFunctionAssignmentInspection extends PyInspection {
+  @Nls
+  @NotNull
+  @Override
+  public String getDisplayName() {
+    return PyBundle.message("INSP.NAME.none.function.assignment");
+  }
+
+  @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 visitPyAssignmentStatement(PyAssignmentStatement node) {
+      final PyExpression value = node.getAssignedValue();
+      if (value instanceof PyCallExpression) {
+        final PyType type = myTypeEvalContext.getType(value);
+        final PyExpression callee = ((PyCallExpression)value).getCallee();
+        if (type instanceof PyNoneType && callee != null) {
+          registerProblem(node, PyBundle.message("INSP.none.function.assignment", callee.getName()));
+        }
+      }
+    }
+  }
+}

python/testData/inspections/PyNoneFunctionAssignmentInspection/noReturn.py

@@ -0,0 +1,6 @@
+__author__ = 'ktisha'
+
+def foo():
+    a = 1
+
+<weak_warning descr="Function foo doesn't return anything">b = foo()</weak_warning>

python/testData/inspections/PyNoneFunctionAssignmentInspection/noType.py

@@ -0,0 +1,6 @@
+__author__ = 'ktisha'
+
+def foo(x):
+    return x
+
+b = foo()

python/testData/inspections/PyNoneFunctionAssignmentInspection/pass.py

@@ -0,0 +1,6 @@
+__author__ = 'ktisha'
+
+def foo():
+    pass
+
+<weak_warning descr="Function foo doesn't return anything">b = foo()</weak_warning>

python/testData/inspections/PyNoneFunctionAssignmentInspection/returnNone.py

@@ -0,0 +1,6 @@
+__author__ = 'ktisha'
+
+def foo():
+    return None
+
+<weak_warning descr="Function foo doesn't return anything">b = foo()</weak_warning>

python/testData/inspections/PyNoneFunctionAssignmentInspection/trueNegative.py

@@ -0,0 +1,6 @@
+__author__ = 'ktisha'
+
+def foo():
+    return 3
+
+b = foo()

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

@@ -0,0 +1,35 @@
+package com.jetbrains.python.inspections;
+
+import com.jetbrains.python.fixtures.PyTestCase;
+
+/**
+ * User: ktisha
+ */
+public class PyNoneFunctionAssignmentInspectionTest extends PyTestCase {
+
+  public void testPass() {
+    doTest();
+  }
+
+  public void testReturnNone() {
+    doTest();
+  }
+
+  public void testNoReturn() {
+    doTest();
+  }
+
+  public void testTrueNegative() {
+    doTest();
+  }
+
+  public void testNoType() {
+    doTest();
+  }
+
+  private void doTest() {
+    myFixture.configureByFile("inspections/PyNoneFunctionAssignmentInspection/" + getTestName(true) + ".py");
+    myFixture.enableInspections(PyNoneFunctionAssignmentInspection.class);
+    myFixture.checkHighlighting(false, false, true);
+  }
+}