Methods to implement will be printed in the same order as shown in dialog (PY-25906)

Every of them was inserted after statement list so the last method becomes the first.
The problem is fixed by reverting writing order.

python/src/com/jetbrains/python/codeInsight/override/PyOverrideImplementUtil.java

@@ -146,9 +146,7 @@ public class PyOverrideImplementUtil {
     }.execute();
   }
 
-  private static void write(@NotNull final PyClass pyClass,
-                            @NotNull final List<PyMethodMember> newMembers,
-                            @NotNull final Editor editor, boolean implement) {
+  private static void write(@NotNull PyClass pyClass, @NotNull List<PyMethodMember> newMembers, @NotNull Editor editor, boolean implement) {
     final PyStatementList statementList = pyClass.getStatementList();
     final int offset = editor.getCaretModel().getOffset();
     PsiElement anchor = null;
@@ -161,10 +159,11 @@ public class PyOverrideImplementUtil {
     }
 
     PyFunction element = null;
-    for (PyMethodMember newMember : newMembers) {
-      PyFunction baseFunction = (PyFunction)newMember.getPsiElement();
+    final LanguageLevel languageLevel = LanguageLevel.forElement(statementList);
+    for (PyMethodMember newMember : Lists.reverse(newMembers)) {
+      final PyFunction baseFunction = (PyFunction)newMember.getPsiElement();
       final PyFunctionBuilder builder = buildOverriddenFunction(pyClass, baseFunction, implement);
-      PyFunction function = builder.addFunctionAfter(statementList, anchor, LanguageLevel.forElement(statementList));
+      final PyFunction function = builder.addFunctionAfter(statementList, anchor, languageLevel);
       element = CodeInsightUtilCore.forcePsiPostprocessAndRestoreElement(function);
     }
 

python/testData/override/implementationOrder.py

@@ -0,0 +1,15 @@
+from abc import abstractmethod
+
+
+class Abstract:
+    @abstractmethod
+    def foo(self):
+        pass
+
+    @abstractmethod
+    def bar(self):
+        pass
+
+
+class Impl(Abstract):
+    pass

python/testData/override/implementationOrder_after.py

@@ -0,0 +1,20 @@
+from abc import abstractmethod
+
+
+class Abstract:
+    @abstractmethod
+    def foo(self):
+        pass
+
+    @abstractmethod
+    def bar(self):
+        pass
+
+
+class Impl(Abstract):
+    def foo(self):
+        pass
+
+    def bar(self):
+        pass
+

python/testSrc/com/jetbrains/python/PyOverrideTest.java

@@ -5,6 +5,7 @@ package com.jetbrains.python;
 
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.util.containers.ContainerUtil;
 import com.jetbrains.python.codeInsight.override.PyMethodMember;
 import com.jetbrains.python.codeInsight.override.PyOverrideImplementUtil;
 import com.jetbrains.python.fixtures.PyTestCase;
@@ -14,6 +15,7 @@ import com.jetbrains.python.psi.PyFile;
 import com.jetbrains.python.psi.PyFunction;
 import com.jetbrains.python.psi.stubs.PyClassNameIndex;
 
+import java.util.Arrays;
 import java.util.Collections;
 
 /**
@@ -119,6 +121,21 @@ public class PyOverrideTest extends PyTestCase {
     doTest();
   }
 
+  // PY-25906
+  public void testImplementationOrder() {
+    myFixture.configureByFile("override/" + getTestName(true) + ".py");
+
+    final PyFunction[] toImplement = getTopLevelClass(0).getMethods();
+    assertEquals(Arrays.asList("foo", "bar"), ContainerUtil.map(toImplement, PyFunction::getName));
+
+    PyOverrideImplementUtil.overrideMethods(myFixture.getEditor(),
+                                            getTopLevelClass(1),
+                                            ContainerUtil.map(toImplement, PyMethodMember::new),
+                                            true);
+
+    myFixture.checkResultByFile("override/" + getTestName(true) + "_after.py", true);
+  }
+
   public void testPy3k() {
     doTest3k();
   }