[Iter] test merge and zip

tests/Psl/Iter/MergeTest.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Iter;
+
+use PHPUnit\Framework\TestCase;
+use Psl\Iter;
+
+class MergeTest extends TestCase
+{
+    public function testMap(): void
+    {
+        $result = Iter\merge([1, 2], [9, 8]);
+        
+        $entries = Iter\to_array(Iter\enumerate($result));
+
+        static::assertSame($entries[0], [0, 1]);
+        static::assertSame($entries[1], [1, 2]);
+        static::assertSame($entries[2], [0, 9]);
+        static::assertSame($entries[3], [1, 8]);
+    }
+}

tests/Psl/Iter/ZipTest.php

@@ -38,4 +38,11 @@ class ZipTest extends TestCase
         static::assertSame([2, 2, 2], $k);
         static::assertSame([3, 7, 12], $v);
     }
+    
+    public function testZipWithZeroIterables(): void
+    {
+        $result = Iter\zip(...[]);
+        
+        self::assertCount(0, $result);
+    }
 }