Issue #3336401: Create tests for basic module functionalities

tests/src/Functional/ConfigPartialExportTest.php

+<?php
+
+namespace Drupal\Tests\config_partial_export\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Class to functional tests in config partial export module.
+ */
+class ConfigPartialExportTest extends BrowserTestBase {
+
+  /**
+   * Administrative User.
+   *
+   * @var \Drupal\Core\Session\AccountInterface
+   */
+  protected $adminUser;
+
+  /**
+   * {@inheritDoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritDoc}
+   */
+  protected static $modules = [
+    'config',
+  ];
+
+  /**
+   * {@inheritDoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->adminUser = $this->drupalCreateUser([], 'user', TRUE);
+  }
+
+  /**
+   * Test if the module has been installed and uninstalled correctly.
+   */
+  public function testInstallAndUninstall() {
+    $this->drupalLogin($this->adminUser);
+    $this->drupalGet('admin/modules');
+    $this->submitForm(["modules[config_partial_export][enable]" => TRUE], 'Install');
+    $this->assertSession()->pageTextContains('Module Configuration Partial Export has been enabled.');
+    // Uninstall the module.
+    $this->drupalGet('admin/modules/uninstall');
+    $this->submitForm(["uninstall[config_partial_export]" => TRUE], 'Uninstall');
+    $this->submitForm([], 'Uninstall');
+    $this->assertSession()->pageTextContains('The selected modules have been uninstalled.');
+  }
+
+}