Administration: Fix DivisionByZeroError in wp_dashboard_quota() and d…

src/wp-admin/includes/dashboard.php

@@ -1661,6 +1661,10 @@ function wp_dashboard_quota() {
 	$quota = get_space_allowed();
 	$used  = get_space_used();
 
+	if ( $quota <= 0 ) {
+		return;
+	}
+
 	if ( $used > $quota ) {
 		$percentused = '100';
 	} else {

src/wp-admin/includes/ms.php

@@ -256,7 +256,7 @@ function display_space_usage() {
 	$space_allowed = get_space_allowed();
 	$space_used    = get_space_used();
 
-	$percent_used = ( $space_used / $space_allowed ) * 100;
+	$percent_used = $space_allowed > 0 ? ( $space_used / $space_allowed ) * 100 : 0;
 
 	$space = size_format( $space_allowed * MB_IN_BYTES );
 	?>

tests/phpunit/tests/multisite/wpDashboardQuota.php

@@ -0,0 +1,200 @@
+<?php
+
+/**
+ * Tests specific to `wp_dashboard_quota()` in multisite.
+ *
+ * These tests filter `get_space_allowed` and `pre_get_space_used`
+ * as those functions are tested elsewhere.
+ *
+ * @ticket 65439
+ * @group ms-required
+ * @group multisite
+ */
+
+class Tests_Multisite_WpDashboardQuota extends WP_UnitTestCase {
+
+	public static function set_up_before_class() {
+		parent::set_up_before_class();
+
+		if ( ! function_exists( 'wp_dashboard_quota' ) ) {
+			require_once ABSPATH . 'wp-admin/includes/dashboard.php';
+		}
+	}
+
+	public function set_up() {
+		parent::set_up();
+		update_site_option( 'upload_space_check_disabled', false );
+		wp_set_current_user( self::factory()->user->create( array( 'role' => 'administrator' ) ) );
+	}
+
+	/**
+	 * wp_dashboard_quota() must not throw a DivisionByZeroError when
+	 * quota is 0 and used space is 0.
+	 *
+	 * @ticket 65439
+	 */
+	public function test_quota_zero_used_zero_does_not_throw() {
+		add_filter( 'get_space_allowed', '__return_zero' );
+		add_filter( 'pre_get_space_used', '__return_zero' );
+
+		$threw = false;
+		try {
+			ob_start();
+			wp_dashboard_quota();
+			ob_end_clean();
+		} catch ( \DivisionByZeroError $e ) {
+			ob_end_clean();
+			$threw = true;
+		}
+
+		remove_filter( 'get_space_allowed', '__return_zero' );
+		remove_filter( 'pre_get_space_used', '__return_zero' );
+
+		$this->assertFalse( $threw, 'wp_dashboard_quota() must not throw DivisionByZeroError when quota is 0.' );
+	}
+
+	/**
+	 * wp_dashboard_quota() must not throw when quota is 0 and space is used.
+	 *
+	 * @ticket 65439
+	 */
+	public function test_quota_zero_used_nonzero_does_not_throw() {
+		add_filter( 'get_space_allowed', '__return_zero' );
+		add_filter( 'pre_get_space_used', array( $this, '_filter_space_5' ) );
+
+		$threw = false;
+		try {
+			ob_start();
+			wp_dashboard_quota();
+			ob_end_clean();
+		} catch ( \DivisionByZeroError $e ) {
+			ob_end_clean();
+			$threw = true;
+		}
+
+		remove_filter( 'get_space_allowed', '__return_zero' );
+		remove_filter( 'pre_get_space_used', array( $this, '_filter_space_5' ) );
+
+		$this->assertFalse( $threw, 'wp_dashboard_quota() must not throw DivisionByZeroError when quota is 0 and space is used.' );
+	}
+
+	/**
+	 * wp_dashboard_quota() must not throw when quota is negative.
+	 *
+	 * @ticket 65439
+	 */
+	public function test_quota_negative_does_not_throw() {
+		add_filter( 'get_space_allowed', array( $this, '_filter_space_negative' ) );
+		add_filter( 'pre_get_space_used', '__return_zero' );
+
+		$threw = false;
+		try {
+			ob_start();
+			wp_dashboard_quota();
+			ob_end_clean();
+		} catch ( \DivisionByZeroError $e ) {
+			ob_end_clean();
+			$threw = true;
+		}
+
+		remove_filter( 'get_space_allowed', array( $this, '_filter_space_negative' ) );
+		remove_filter( 'pre_get_space_used', '__return_zero' );
+
+		$this->assertFalse( $threw, 'wp_dashboard_quota() must not throw when quota is negative.' );
+	}
+
+	/**
+	 * wp_dashboard_quota() must render output normally for a non-zero quota.
+	 *
+	 * @ticket 65439
+	 */
+	public function test_quota_nonzero_renders_output() {
+		add_filter( 'get_space_allowed', array( $this, '_filter_space_100' ) );
+		add_filter( 'pre_get_space_used', array( $this, '_filter_space_5' ) );
+
+		ob_start();
+		wp_dashboard_quota();
+		$output = ob_get_clean();
+
+		remove_filter( 'get_space_allowed', array( $this, '_filter_space_100' ) );
+		remove_filter( 'pre_get_space_used', array( $this, '_filter_space_5' ) );
+
+		$this->assertStringContainsString( 'Storage Space', $output, 'wp_dashboard_quota() must render the Storage Space widget for a normal quota.' );
+	}
+
+	/**
+	 * wp_dashboard_quota() must produce no output when quota is 0
+	 * (early return, nothing to display).
+	 *
+	 * @ticket 65439
+	 */
+	public function test_quota_zero_produces_no_output() {
+		add_filter( 'get_space_allowed', '__return_zero' );
+		add_filter( 'pre_get_space_used', '__return_zero' );
+
+		ob_start();
+		wp_dashboard_quota();
+		$output = ob_get_clean();
+
+		remove_filter( 'get_space_allowed', '__return_zero' );
+		remove_filter( 'pre_get_space_used', '__return_zero' );
+
+		$this->assertSame( '', $output, 'wp_dashboard_quota() must produce no output when quota is 0.' );
+	}
+
+	public function _filter_space_5() {
+		return 5;
+	}
+
+	public function _filter_space_100() {
+		return 100;
+	}
+
+	public function _filter_space_negative() {
+		return -1;
+	}
+
+	/**
+	 * display_space_usage() must not throw a DivisionByZeroError when quota is 0.
+	 *
+	 * @ticket 65439
+	 */
+	public function test_display_space_usage_quota_zero_does_not_throw() {
+		add_filter( 'get_space_allowed', '__return_zero' );
+		add_filter( 'pre_get_space_used', '__return_zero' );
+
+		$threw = false;
+		try {
+			ob_start();
+			display_space_usage();
+			ob_end_clean();
+		} catch ( \DivisionByZeroError $e ) {
+			ob_end_clean();
+			$threw = true;
+		}
+
+		remove_filter( 'get_space_allowed', '__return_zero' );
+		remove_filter( 'pre_get_space_used', '__return_zero' );
+
+		$this->assertFalse( $threw, 'display_space_usage() must not throw DivisionByZeroError when quota is 0.' );
+	}
+
+	/**
+	 * display_space_usage() must render output normally for a non-zero quota.
+	 *
+	 * @ticket 65439
+	 */
+	public function test_display_space_usage_quota_nonzero_renders_output() {
+		add_filter( 'get_space_allowed', array( $this, '_filter_space_100' ) );
+		add_filter( 'pre_get_space_used', array( $this, '_filter_space_5' ) );
+
+		ob_start();
+		display_space_usage();
+		$output = ob_get_clean();
+
+		remove_filter( 'get_space_allowed', array( $this, '_filter_space_100' ) );
+		remove_filter( 'pre_get_space_used', array( $this, '_filter_space_5' ) );
+
+		$this->assertStringContainsString( 'Used:', $output, 'display_space_usage() must render usage output for a normal quota.' );
+	}
+}