test: Add verification for leaves method ordering in NestedSetsQueryBehaviorTest.

tests/NestedSetsBehaviorTest.php

@@ -1719,7 +1719,7 @@ public function testAppendChildNodeToRootCreatesValidTreeStructure(): void
             self::assertEquals(
                 1,
                 $child->depth,
-                'Child node depth should be \'1\' after being appended to the root node.',
+                'Child node depth should be \'1\' after being \'appendTo\' the root node.',
             );
         } catch (Exception $e) {
             self::fail('Real insertion failed: ' . $e->getMessage());
@@ -1753,12 +1753,12 @@ public function testReturnShiftedLeftRightAttributesWhenChildAppendedToRoot(): v
         self::assertEquals(
             2,
             $child->lft,
-            'Child node left value should be \'2\' after being appended to the root node.',
+            'Child node left value should be \'2\' after being \'appendTo\' to the root node.',
         );
         self::assertEquals(
             3,
             $child->rgt,
-            'Child node right value should be \'3\' after being appended to the root node.',
+            'Child node right value should be \'3\' after being \'appendTo\' the root node.',
         );
         self::assertNotEquals(
             0,
@@ -1979,26 +1979,26 @@ public function testMakeRootWithRunValidationParameterUsingStrictValidation(): v
 
         self::assertNotNull(
             $persistedNode,
-            'Node should exist in database after makeRoot with validation disabled.',
+            'Node should exist in database after \'makeRoot\' with validation disabled.',
         );
         self::assertTrue(
             $persistedNode->isRoot(),
-            'Node should be a root node after makeRoot operation.',
+            'Node should be a root node after \'makeRoot\' operation.',
         );
         self::assertEquals(
             1,
             $persistedNode->lft,
-            'Root node should have left value of 1.',
+            'Root node should have left value of \'1\'.',
         );
         self::assertEquals(
             2,
             $persistedNode->rgt,
-            'Root node should have right value of 2.',
+            'Root node should have right value of \'2\'.',
         );
         self::assertEquals(
             0,
             $persistedNode->depth,
-            'Root node should have depth of 0.',
+            'Root node should have depth of \'0\'.',
         );
     }
 
@@ -2021,7 +2021,7 @@ public function testPrependToWithRunValidationParameterUsingStrictValidation():
 
         self::assertFalse(
             $resultWithValidation,
-            "\'prependTo()\' with \'runValidation=true\' should return \'false\' when validation fails.",
+            '\'prependTo()\' with \'runValidation=true\' should return \'false\' when validation fails.',
         );
         self::assertTrue(
             $hasError1,
@@ -2310,13 +2310,14 @@ public function testChildrenMethodRequiresOrderByForCorrectTreeTraversal(): void
             self::assertInstanceOf(
                 Tree::class,
                 $child,
-                "Child at index {$index} should be an instance of \'Tree\'.",
+                "Child at index {$index} should be an instance of 'Tree'.",
             );
+
             if (isset($expectedOrder[$index])) {
                 self::assertEquals(
                     $expectedOrder[$index],
                     $child->getAttribute('name'),
-                    "Child at index {$index} should be {$expectedOrder[$index]} in correct \'lft\' order.",
+                    "Child at index {$index} should be {$expectedOrder[$index]} in correct 'lft' order.",
                 );
             }
         }

tests/NestedSetsQueryBehaviorTest.php

@@ -111,13 +111,80 @@ public function testRootsMethodRequiresOrderByForCorrectTreeTraversal(): void
             self::assertInstanceOf(
                 MultipleTree::class,
                 $root,
-                "Root at index {$index} should be an instance of \'MultipleTree\'.",
+                "Root at index {$index} should be an instance of 'MultipleTree'.",
             );
+
             if (isset($expectedOrder[$index])) {
                 self::assertEquals(
                     $expectedOrder[$index],
                     $root->getAttribute('name'),
-                    "Root at index {$index} should be {$expectedOrder[$index]} in correct \'tree\' order.",
+                    "Root at index {$index} should be {$expectedOrder[$index]} in correct 'tree' order.",
+                );
+            }
+        }
+    }
+
+    public function testLeavesMethodRequiresLeftAttributeOrderingForConsistentResults(): void
+    {
+        $this->createDatabase();
+
+        $root = new MultipleTree(['name' => 'Root']);
+
+        $root->makeRoot();
+
+        $leaf1 = new MultipleTree(['name' => 'Leaf A']);
+
+        $leaf1->appendTo($root);
+
+        $leaf2 = new MultipleTree(['name' => 'Leaf B']);
+
+        $leaf2->appendTo($root);
+
+        $initialLeaves = MultipleTree::find()->leaves()->all();
+
+        self::assertCount(
+            2,
+            $initialLeaves,
+            'Should have exactly \'2\' initial leaf nodes.',
+        );
+
+        $command = $this->getDb()->createCommand();
+
+        $command->update('multiple_tree', ['lft' => 3, 'rgt' => 4], ['name' => 'Leaf B'])->execute();
+        $command->update('multiple_tree', ['lft' => 5, 'rgt' => 6], ['name' => 'Leaf A'])->execute();
+        $command->update('multiple_tree', ['lft' => 1, 'rgt' => 7], ['name' => 'Root'])->execute();
+
+        $leaves = MultipleTree::find()->leaves()->all();
+
+        /** @phpstan-var array<array{name: string, lft: int}> */
+        $expectedLeaves = [
+            ['name' => 'Leaf B', 'lft' => 3],
+            ['name' => 'Leaf A', 'lft' => 5],
+        ];
+
+        self::assertCount(
+            2,
+            $leaves,
+            'Should return exactly \'2\' leaf nodes.',
+        );
+
+        foreach ($leaves as $index => $leaf) {
+            self::assertInstanceOf(
+                MultipleTree::class,
+                $leaf,
+                "Leaf at index {$index} should be an instance of 'MultipleTree'.",
+            );
+
+            if (isset($expectedLeaves[$index])) {
+                self::assertEquals(
+                    $expectedLeaves[$index]['name'],
+                    $leaf->getAttribute('name'),
+                    "Leaf at index {$index} should be {$expectedLeaves[$index]['name']} in correct order.",
+                );
+                self::assertEquals(
+                    $expectedLeaves[$index]['lft'],
+                    $leaf->getAttribute('lft'),
+                    "Leaf at index {$index} should have left value {$expectedLeaves[$index]['lft']}.",
                 );
             }
         }