Improve test code coverage

Author: dakujem

tests/iterators.phpt

@@ -220,30 +220,50 @@ require_once __DIR__ . '/setup.php';
 (function () {
     $root = Preset::wikiTree();
 
+    //
     // level-order (?), leaves only (the default)
-    $str = [];
-    foreach (new RecursiveIteratorIterator(new Native($root)) as $node) {
+    //
+
+    $str = $keys = [];
+    foreach (new RecursiveIteratorIterator(new Native($root)) as $key => $node) {
         $str[] = $node->data();
+        $keys[] = $key;
     }
     Assert::same('A,C,E,H', implode(',', $str));
-    $str = [];
-    foreach (new RecursiveIteratorIterator(new Native($root), RecursiveIteratorIterator::LEAVES_ONLY) as $node) {
+    Assert::same('0,0,1,0', implode(',', $keys));
+
+    $str = $keys = [];
+    foreach (new RecursiveIteratorIterator(new Native($root), RecursiveIteratorIterator::LEAVES_ONLY) as $key => $node) {
         $str[] = $node->data();
+        $keys[] = $key;
     }
     Assert::same('A,C,E,H', implode(',', $str));
+    Assert::same('0,0,1,0', implode(',', $keys));
 
+    //
     // pre-order, all nodes
-    $str = [];
-    foreach (new RecursiveIteratorIterator(new Native($root), RecursiveIteratorIterator::SELF_FIRST) as $node) {
+    //
+
+    $str = $keys = [];
+    foreach (new RecursiveIteratorIterator(new Native($root), RecursiveIteratorIterator::SELF_FIRST) as $key => $node) {
         $str[] = $node->data();
+        $keys[] = $key;
     }
+    // F,B,A,D,C,E,G,I,H is the iteration order of nodes, which corresponds to the following child indexes (iteration keys):
+    // 0,0,0,1,0,1,1,0,0
     Assert::same('F,B,A,D,C,E,G,I,H', implode(',', $str));
+    Assert::same('0,0,0,1,0,1,1,0,0', implode(',', $keys));
 
+    //
     // post-order, all nodes
-    $str = [];
-    foreach (new RecursiveIteratorIterator(new Native($root), RecursiveIteratorIterator::CHILD_FIRST) as $node) {
+    //
+
+    $str = $keys = [];
+    foreach (new RecursiveIteratorIterator(new Native($root), RecursiveIteratorIterator::CHILD_FIRST) as $key => $node) {
         $str[] = $node->data();
+        $keys[] = $key;
     }
     Assert::same('A,C,E,D,B,H,I,G,F', implode(',', $str));
+    Assert::same('0,0,1,1,0,0,0,1,0', implode(',', $keys));
 })();
 

tests/traversal-private.phpt

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Dakujem\Test;
+
+use Dakujem\Oliva\Iterator\Traversal;
+use Error;
+use Tester\Assert;
+
+require_once __DIR__ . '/setup.php';
+
+(function () {
+    // This test exists for code coverage purposes only... ¯\_(ツ)_/¯
+    // We might remove the private constructor constraint as well.
+    Assert::throws(function () {
+        /** @noinspection */
+        new Traversal();
+    }, Error::class, 'Call to private Dakujem\Oliva\Iterator\Traversal::__construct() from global scope');
+})();

tests/tree.phpt

@@ -126,3 +126,12 @@ require_once __DIR__ . '/setup.php';
     Assert::same(['original' => $node], $parent->children());
 })();
 
+(function () {
+    $parent = new Node(null);
+    $node = new NotMovable(null);
+
+    Assert::throws(function () use ($parent, $node) {
+        Tree::linkChildren($parent, [$node]);
+    }, NodeNotMovable::class, 'Encountered a non-movable node while manipulating a tree.');
+})();
+