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Improve robustness of page cache test for Site Health #10855

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d4817d6
Site Health: Improve page cache detection robustness.
westonruter Feb 3, 2026
a2d3183
Site Health: Fix detection for x-srcache-store-status header.
westonruter Feb 3, 2026
9aa2b94
Improve docs and typing for get_page_cache_headers method
westonruter Feb 3, 2026
ed21256
Tidy test_get_page_cache
westonruter Feb 3, 2026
a6ffaaf
Merge branch 'trunk' of https://github.com/WordPress/wordpress-develo…
westonruter Feb 11, 2026
f9512d5
Merge branch 'trunk' into trac-64370
westonruter Feb 17, 2026
5a7b2f5
Rename good_basic_auth to has_basic_auth since not necessarily good
westonruter Feb 17, 2026
de5b813
Fix typo in comment
westonruter Feb 17, 2026
c51daae
Replace bool type cast with explicit equality for preg_match() return…
westonruter Feb 17, 2026
913d8cb
Remove vulgarity from test
westonruter Feb 17, 2026
c63928a
Move via header up to standard section
westonruter Feb 17, 2026
6f1ff6a
Re-organized cache headers
westonruter Feb 17, 2026
4af0c36
Add nginx section and add links for Varnish
westonruter Feb 17, 2026
1aded16
Move x-proxy-cache into Nginx section
westonruter Feb 17, 2026
c67ffac
Replace word boundary for HIT with anchor, comma, or whitespace
westonruter Feb 17, 2026
40770d1
Add documentation for x-cache-enabled and x-cache-disabled
westonruter Feb 17, 2026
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97 changes: 78 additions & 19 deletions src/wp-admin/includes/class-wp-site-health.php
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Original file line number Diff line number Diff line change
Expand Up @@ -3428,22 +3428,20 @@ public function is_development_environment() {
}

/**
* Returns a list of headers and its verification callback to verify if page cache is enabled or not.
*
* Note: key is header name and value could be callable function to verify header value.
* Empty value mean existence of header detect page cache is enabled.
* Returns a mapping from response headers to an optional callback to verify if page cache is enabled or not.
*
* @since 6.1.0
*
* @return array List of client caching headers and their (optional) verification callbacks.
* @return array<string, ?callable> Mapping of page caching headers and their (optional) verification callbacks.
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@dmsnell dmsnell Feb 17, 2026

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the previous comment explained what an empty value means, but this change removes that knowledge. was that intentional?

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@westonruter westonruter Feb 17, 2026

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I thought it was redundant, but it seems it isn't. How about this:

Suggested change
* @return array<string, ?callable> Mapping of page caching headers and their (optional) verification callbacks.
* @return array<string, ?callable> Mapping of page caching headers and their (optional) verification callbacks.
A null value means a simple existence check is used for the header.

*/
public function get_page_cache_headers() {
public function get_page_cache_headers(): array {

$cache_hit_callback = static function ( $header_value ) {
return str_contains( strtolower( $header_value ), 'hit' );
return 1 === preg_match( '/(^| |,)HIT(,| |$)/i', $header_value );
};

$cache_headers = array(
// Standard HTTP caching headers.
'cache-control' => static function ( $header_value ) {
return (bool) preg_match( '/max-age=[1-9]/', $header_value );
},
Expand All @@ -3453,36 +3451,97 @@ public function get_page_cache_headers() {
'age' => static function ( $header_value ) {
return is_numeric( $header_value ) && $header_value > 0;
},
'last-modified' => '',
'etag' => '',
'last-modified' => null,
'etag' => null,
'via' => null,

/**
* Custom caching headers.
*
* These do not seem to be actually used by any caching layers. There were first introduced in a Site Health
* test in the AMP plugin. They were copied into the Performance Lab plugin's Site Health test before they
* were merged into core.
*
* @link https://github.com/ampproject/amp-wp/pull/6849
* @link https://github.com/WordPress/performance/pull/263
* @link https://core.trac.wordpress.org/changeset/54043
*/
'x-cache-enabled' => static function ( $header_value ) {
return 'true' === strtolower( $header_value );
return ( 'true' === strtolower( $header_value ) );
},
'x-cache-disabled' => static function ( $header_value ) {
return ( 'on' !== strtolower( $header_value ) );
},
Comment on lines +3458 to 3474
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@westonruter westonruter Feb 17, 2026

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I'm inclined to remove these entirely since it seems they were originally introduced erroneously in the AMP plugin. I can't find any caching layers that actually use them. There are a few hundred mentions of them on GitHub, nevertheless: https://github.com/search?q=%2Fx-cache-(enabled%7Cdisabled)%2F&type=code

'x-srcache-store-status' => $cache_hit_callback,
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@westonruter westonruter Feb 3, 2026

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This was incorrect. Now fixed.

'x-srcache-fetch-status' => $cache_hit_callback,

// Generic caching proxies (Nginx, Varnish, etc.)
/**
* CloudFlare.
*
* @link https://developers.cloudflare.com/cache/concepts/cache-responses/
*/
'cf-cache-status' => $cache_hit_callback,

/**
* Fastly.
*
* @link https://www.fastly.com/documentation/reference/http/http-headers/X-Cache/
*/
'x-cache' => $cache_hit_callback,
'x-cache-status' => $cache_hit_callback,

/**
* LightSpeed.
*
* @link https://docs.litespeedtech.com/lscache/devguide/controls/#x-litespeed-cache
*/
'x-litespeed-cache' => $cache_hit_callback,

/**
* OpenResty srcache-nginx-module.
*
* The `x-srcache-store-status` header indicates if the response was stored in the cache.
* Valid values include `STORE` and `BYPASS`.
*
* The `x-srcache-fetch-status` header indicates if the response was fetched from the cache.
* Valid values include `HIT`, `MISS`, and `BYPASS`.
*
* @link https://github.com/openresty/srcache-nginx-module
*/
'x-srcache-store-status' => static function ( $header_value ) {
return 'store' === strtolower( $header_value );
},
'x-srcache-fetch-status' => $cache_hit_callback,

/**
* Nginx.
*
* @link https://blog.nginx.org/blog/nginx-caching-guide
* @link https://www.inmotionhosting.com/support/website/nginx-cache-management/
*/
'x-cache-status' => $cache_hit_callback,
'x-proxy-cache' => $cache_hit_callback,
'via' => '',

// Cloudflare
'cf-cache-status' => $cache_hit_callback,
/**
* Varnish Cache.
*
* A header with a single number indicates it was not cached. If there are two numbers (or more), then this
* indicates the response was cached.
*
* @link https://vinyl-cache.org/docs/2.1/faq/http.html
* @link https://www.fastly.com/documentation/reference/http/http-headers/X-Varnish/
* @link https://www.linuxjournal.com/content/speed-your-web-site-varnish
*/
'x-varnish' => static function ( $header_value ) {
return 1 === preg_match( '/^\d+ \d+/', $header_value );
},
);

/**
* Filters the list of cache headers supported by core.
*
* @since 6.1.0
*
* @param array $cache_headers Array of supported cache headers.
* @param array<string, ?callable> $cache_headers Mapping of page caching headers and their (optional) verification callbacks.
*/
return apply_filters( 'site_status_page_cache_supported_cache_headers', $cache_headers );
return (array) apply_filters( 'site_status_page_cache_supported_cache_headers', $cache_headers );
}

/**
Expand Down
106 changes: 91 additions & 15 deletions tests/phpunit/tests/admin/wpSiteHealth.php
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Original file line number Diff line number Diff line change
Expand Up @@ -12,10 +12,8 @@ class Tests_Admin_wpSiteHealth extends WP_UnitTestCase {
* An instance of the class to test.
*
* @since 6.1.0
*
* @var WP_Site_Health
*/
private $instance;
private WP_Site_Health $instance;

public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
// Include the `WP_Site_Health` file.
Expand Down Expand Up @@ -172,7 +170,7 @@ public function data_cron_health_checks() {
* @covers ::get_page_cache_headers()
* @covers ::check_for_page_caching()
*/
public function test_get_page_cache( $responses, $expected_status, $expected_label, $good_basic_auth = null, $delay_the_response = false ) {
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@westonruter westonruter Feb 17, 2026

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Note that $good_basic_auth was previously only either null or false, so this is now changed to be an actual boolean with true or false.

public function test_get_page_cache( array $responses, string $expected_status, string $expected_label, bool $has_basic_auth = false, bool $delay_the_response = false ) {
$expected_props = array(
'badge' => array(
'label' => __( 'Performance' ),
Expand All @@ -183,7 +181,7 @@ public function test_get_page_cache( $responses, $expected_status, $expected_lab
'label' => $expected_label,
);

if ( null !== $good_basic_auth ) {
if ( $has_basic_auth ) {
$_SERVER['PHP_AUTH_USER'] = 'admin';
$_SERVER['PHP_AUTH_PW'] = 'password';
}
Expand All @@ -200,7 +198,7 @@ static function () use ( $threshold ) {

add_filter(
'pre_http_request',
function ( $response, $parsed_args ) use ( &$responses, &$is_unauthorized, $good_basic_auth, $delay_the_response, $threshold ) {
function ( $response, $parsed_args ) use ( &$responses, &$is_unauthorized, $has_basic_auth, $delay_the_response, $threshold ) {

$expected_response = array_shift( $responses );

Expand All @@ -219,7 +217,7 @@ function ( $response, $parsed_args ) use ( &$responses, &$is_unauthorized, $good
);
}

if ( null !== $good_basic_auth ) {
if ( $has_basic_auth ) {
$this->assertArrayHasKey(
'Authorization',
$parsed_args['headers']
Expand Down Expand Up @@ -263,9 +261,15 @@ function ( $response, $parsed_args ) use ( &$responses, &$is_unauthorized, $good
*
* @ticket 56041
*
* @return array[]
* @return array<string, array{
* responses: array<int, string|array<string, string|string[]>>,
* expected_status: 'recommended'|'critical'|'good',
* expected_label: string,
* good_basic_auth?: bool,
* delay_the_response?: bool,
* }>
*/
public function data_get_page_cache() {
public function data_get_page_cache(): array {
$recommended_label = 'Page cache is not detected but the server response time is OK';
$good_label = 'Page cache is detected and the server response time is good';
$critical_label = 'Page cache is not detected and the server response time is slow';
Expand All @@ -278,13 +282,13 @@ public function data_get_page_cache() {
),
'expected_status' => 'recommended',
'expected_label' => $error_label,
'good_basic_auth' => false,
'has_basic_auth' => true,
),
'no-cache-control' => array(
'responses' => array_fill( 0, 3, array() ),
'expected_status' => 'critical',
'expected_label' => $critical_label,
'good_basic_auth' => null,
'has_basic_auth' => false,
'delay_the_response' => true,
),
'no-cache' => array(
Expand All @@ -310,7 +314,7 @@ public function data_get_page_cache() {
'responses' => array_fill( 0, 3, array( 'cache-control' => 'no-cache' ) ),
'expected_status' => 'critical',
'expected_label' => $critical_label,
'good_basic_auth' => null,
'has_basic_auth' => false,
'delay_the_response' => true,
),
'age' => array(
Expand Down Expand Up @@ -366,7 +370,7 @@ public function data_get_page_cache() {
),
'expected_status' => 'critical',
'expected_label' => $critical_label,
'good_basic_auth' => null,
'has_basic_auth' => false,
'delay_the_response' => true,
),
'cache-control-with-basic-auth' => array(
Expand All @@ -377,7 +381,7 @@ public function data_get_page_cache() {
),
'expected_status' => 'good',
'expected_label' => $good_label,
'good_basic_auth' => true,
'has_basic_auth' => true,
),
'x-cache-enabled' => array(
'responses' => array_fill(
Expand All @@ -396,7 +400,7 @@ public function data_get_page_cache() {
),
'expected_status' => 'critical',
'expected_label' => $critical_label,
'good_basic_auth' => null,
'has_basic_auth' => false,
'delay_the_response' => true,
),
'x-cache-disabled' => array(
Expand All @@ -408,6 +412,78 @@ public function data_get_page_cache() {
'expected_status' => 'good',
'expected_label' => $good_label,
),
'false-positive-hit-in-word' => array(
'responses' => array_fill(
0,
3,
array( 'x-cache' => 'no-hit' )
),
'expected_status' => 'recommended',
'expected_label' => $recommended_label,
),
'varnish-header' => array(
'responses' => array_fill(
0,
3,
array( 'x-varnish' => '123 456' )
),
'expected_status' => 'good',
'expected_label' => $good_label,
),
'varnish-header-miss' => array(
'responses' => array_fill(
0,
3,
array( 'x-varnish' => '123' )
),
'expected_status' => 'recommended',
'expected_label' => $recommended_label,
),
'srcache-store-status' => array(
'responses' => array_fill(
0,
3,
array( 'x-srcache-store-status' => 'STORE' )
),
'expected_status' => 'good',
'expected_label' => $good_label,
),
'srcache-store-status-bypass' => array(
'responses' => array_fill(
0,
3,
array( 'x-srcache-store-status' => 'BYPASS' )
),
'expected_status' => 'recommended',
'expected_label' => $recommended_label,
),
'srcache-fetch-status' => array(
'responses' => array_fill(
0,
3,
array( 'x-srcache-fetch-status' => 'HIT' )
),
'expected_status' => 'good',
'expected_label' => $good_label,
),
'last-modified' => array(
'responses' => array_fill(
0,
3,
array( 'last-modified' => 'Wed, 21 Oct 2015 07:28:00 GMT' )
),
'expected_status' => 'good',
'expected_label' => $good_label,
),
'via' => array(
'responses' => array_fill(
0,
3,
array( 'via' => '1.1 varnish' )
),
'expected_status' => 'good',
'expected_label' => $good_label,
),
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@dmsnell dmsnell Feb 17, 2026

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because I’m not familiar with all of these systems, and don’t have any in front of me, I am not reviewing or verifying these tests.

I’m trusting that you confirmed that the responses correspond to what those projects actually produce and that the values here are factually representative.

the CommonCrawl archive would potentially be a valuable archive to mine for this kind of header behavior.

);
}

Expand Down
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