add dummy test (remove this after fixing install bug)

tests/phpunit/CRM/Dataprocessor/DummyTest.php

+<?php
+
+use CRM_Dataprocessor_ExtensionUtil as E;
+
+/**
+ * Dummy TEMPORARY test which requires the reinstallation of the test db
+ * for debugging problems with installation.
+ *
+ * @group headless
+ */
+class CRM_Dataprocessor_Dummy extends CRM_Dataprocessor_TestBase {
+
+  public function setUpHeadless() {
+    // Civi\Test has many helpers, like install(), uninstall(), sql(), and sqlFile().
+    // See: https://docs.civicrm.org/dev/en/latest/testing/phpunit/#civitest
+    return \Civi\Test::headless()
+      ->installMe(__DIR__)
+      ->apply(TRUE);
+  }
+
+  public function testDummy() {
+    $this->assertTrue(TRUE);
+  }
+
+}
+