PEP8-compliant line commenter behavior in Python (PY-3153)

python/src/com/jetbrains/python/PythonCommenter.java

@@ -1,15 +1,17 @@
 package com.jetbrains.python;
 
+import com.intellij.codeInsight.generation.IndentedCommenter;
 import com.intellij.lang.CodeDocumentationAwareCommenter;
 import com.intellij.psi.PsiComment;
 import com.intellij.psi.tree.IElementType;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * @author yole
  */
-public class PythonCommenter implements CodeDocumentationAwareCommenter {
+public class PythonCommenter implements CodeDocumentationAwareCommenter, IndentedCommenter {
   public String getLineCommentPrefix() {
-    return "#";
+    return "# ";
   }
 
   public String getBlockCommentPrefix() {
@@ -62,4 +64,10 @@ public class PythonCommenter implements CodeDocumentationAwareCommenter {
   public boolean isDocumentationComment(PsiComment element) {
     return false;
   }
+
+  @Nullable
+  @Override
+  public Boolean forceIndentedLineComment() {
+    return true;
+  }
 }

python/testData/commenter/indentedComment.py

@@ -0,0 +1,3 @@
+def foo():
+    i = 1<caret>
+    j = 2

python/testData/commenter/indentedComment_after.py

@@ -0,0 +1,3 @@
+def foo():
+    # i = 1
+    j = 2

python/testData/commenter/uncommentWithoutSpace.py

@@ -0,0 +1,3 @@
+def foo():
+    #i = 1<caret>
+    j = 2

python/testData/commenter/uncommentWithoutSpace_after.py

@@ -0,0 +1,3 @@
+def foo():
+    i = 1
+    j = 2

python/testSrc/com/jetbrains/python/PyCommenterTest.java

@@ -0,0 +1,27 @@
+package com.jetbrains.python;
+
+import com.intellij.codeInsight.actions.CodeInsightAction;
+import com.intellij.openapi.actionSystem.ActionManager;
+import com.intellij.openapi.actionSystem.IdeActions;
+import com.jetbrains.python.fixtures.PyTestCase;
+
+/**
+ * @author yole
+ */
+public class PyCommenterTest extends PyTestCase {
+  public void testIndentedComment() {
+    doTest();
+  }
+
+  public void testUncommentWithoutSpace() {
+    doTest();
+  }
+
+  private void doTest() {
+    myFixture.configureByFile("commenter/" + getTestName(true) + ".py");
+    CodeInsightAction action = (CodeInsightAction) ActionManager.getInstance().getAction(IdeActions.ACTION_COMMENT_LINE);
+    action.actionPerformedImpl(myFixture.getFile().getProject(), myFixture.getEditor());
+    myFixture.checkResultByFile("commenter/" + getTestName(true) + "_after.py", true);
+
+  }
+}