PY-22720 Extract Method does Not Preserve Existing Line Breaks

- keep empty lines between statements
- add test

GitOrigin-RevId: 276000bdce7ffee22ecd2e03d2ec4831dd8f6725

python/python-psi-impl/src/com/jetbrains/python/refactoring/extractmethod/PyExtractMethodUtil.java

@@ -566,9 +566,6 @@ public final class PyExtractMethodUtil {
     final PyFunction method = builder.buildFunction();
     final PyStatementList statementList = method.getStatementList();
     for (PsiElement element : elementsRange) {
-      if (element instanceof PsiWhiteSpace) {
-        continue;
-      }
       statementList.add(element);
     }
     final PsiElement child = statementList.getFirstChild();

python/testData/refactoring/extractmethod/PreserveWhitespaceBetweenStatements.after.py

@@ -0,0 +1,12 @@
+class Foo:
+    def bar(self):
+        print('hello')
+
+        <caret>self.extracted()
+
+        return self
+
+    def extracted(self):
+        print('awesome')
+
+        print('world')

python/testData/refactoring/extractmethod/PreserveWhitespaceBetweenStatements.before.py

@@ -0,0 +1,9 @@
+class Foo:
+    def bar(self):
+        print('hello')
+        <selection>
+        print('awesome')
+
+        print('world')
+        </selection>
+        return self

python/testSrc/com/jetbrains/python/refactoring/PyExtractMethodTest.java

@@ -348,4 +348,8 @@ public class PyExtractMethodTest extends LightMarkedTestCase {
   public void testTypedStatements() {
     doTest("greeting");
   }
+
+  public void testPreserveWhitespaceBetweenStatements() {
+    doTest("extracted");
+  }
 }