try testing with older phpunit

.github/workflows/ci.yaml

@@ -58,3 +58,24 @@ jobs:
       - uses: codecov/codecov-action@v1
         with:
           files: ./coverage.xml
+
+  phpunit-8:
+    runs-on: ubuntu-20.04
+    name: Unit tests
+
+    strategy:
+      matrix:
+        php-version:
+          - "7.2"
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: "${{ matrix.php-version }}"
+          coverage: pcov
+      - name: Composer
+        run: composer require --dev phpunit/phpunit ^8
+      - name: PHPUnit Tests
+        run: php ./vendor/bin/phpunit tests  -c tests/phpunit.xml

tests/UrlCallbackTest.php

@@ -85,7 +85,7 @@ class UrlCallbackTest extends TestCase {
 		mkdir($dir);
 		$path = \Icewind\Streams\UrlCallback::wrap($dir, null, null, null, null, $callback);
 		rmdir($path);
-		$this->assertFileDoesNotExist($dir);
+		$this->assertFileNotExists($dir);
 		$this->assertTrue($called);
 	}
 
@@ -112,7 +112,7 @@ class UrlCallbackTest extends TestCase {
 		touch($file);
 		$path = \Icewind\Streams\UrlCallback::wrap($file, null, null, null, null, null, $callback);
 		unlink($path);
-		$this->assertFileDoesNotExist($file);
+		$this->assertFileNotExists($file);
 		$this->assertTrue($called);
 	}